阅读说明：本技术 中空气门弹簧保持器 (Hollow valve spring retainer ) 是由 约翰·康纳尔 马克·马丁 乔伊·福斯马克 于 2019-06-05 设计创作，主要内容包括：本公开提供了“中空气门弹簧保持器”。提供了用于气门机构总成的气门弹簧保持器的方法和系统。在一个实例中,气门弹簧保持器可以是至少部分中空的并且包括在所述气门弹簧保持器的材料内形成通道的内部腔体。所述内部腔体内的空气可以通过通道流体地联接到围绕所述气门弹簧保持器的空气。通过增材制造可以减小所述气门弹簧保持器的质量,并且可以减少所述气门弹簧保持器的制造成本和时间。(The present disclosure provides a "hollow valve spring retainer". Methods and systems for a valve spring retainer for a valvetrain assembly are provided. In one example, the valve spring retainer may be at least partially hollow and include an internal cavity forming a channel within the material of the valve spring retainer. Air within the internal cavity may be fluidly coupled to air surrounding the valve spring retainer through a passage. The mass of the valve spring retainer may be reduced by additive manufacturing, and the manufacturing cost and time of the valve spring retainer may be reduced.)

1. A valve train of an engine, comprising:

A valve spring;

A disc valve spring retainer having a central bore and a plurality of internal cavities concentric with the central bore, the retainer engaging a first end of the valve spring.

2. The valve train of claim 1, wherein the plurality of internal cavities form a continuous air passage surrounding the central bore of the valve spring retainer, each of the internal cavities further comprising a passage coupling the air passage of the respective internal cavity to ambient air surrounding the retainer.

3. The valve train of claim 2, wherein each of the plurality of internal cavities is spaced apart from one another, separated by material of the valve spring retainer, and wherein the plurality of internal cavities has an upwardly curved top and a downwardly curved bottom, the top and bottom of the internal cavities being coupled by a sidewall.

4. The valve train of claim 1, wherein the valve spring is coupled to a stem of a valve, and a position of the valve spring retainer along the stem is retained via a secure attachment of the retainer to the stem, the secure attachment comprising a weld joint.

5. The valve train of claim 4, wherein the first end of the valve spring faces away from a cylinder head, the valve spring further comprising a second end opposite the first end, the second end in contact with a surface of the cylinder head, and wherein the valve spring exerts a spring load on the valve spring retainer at the first end of the valve spring and on the surface of the cylinder head at the second end.

6. The valve train of claim 5, wherein the valve spring retainer is welded to the valve stem such that the valve spring retainer resists displacement from the valve spring and converts the spring load of the valve spring into motion of the valve.

7. The valve train of claim 1, wherein the valve spring retainer has a flat top surface and a stepped lower surface forming a thickest portion of the valve spring retainer proximate the central bore and a thinnest portion proximate an outer edge of the valve spring retainer.

8. A hollow valve spring retainer comprising:

An annular unit having a central bore for receiving a valve stem;

Each hollow cavity is concentric with the central hole, the first cavity is positioned in the annular unit, and the distance from the central hole is different from that of the second channel.

9. The valve spring retainer of claim 8, wherein said central bore extends from a top surface to a bottom surface of said unit, and wherein said first cavity is positioned within said annular unit closer to said central bore and said second channel is positioned within said annular unit closer to an outer edge wall of said valve spring retainer.

10. A valve spring retainer according to claim 9, wherein said bottom surface of said annular unit is stepped, the diameter of the annular unit at the outer rim wall is larger than the diameter at the circumference of the innermost step, the diameter decreasing in a stepwise manner from the top surface to the bottom surface, and the stepped annular unit comprises a first step having a first diameter at the top surface, a second step having a second diameter at the bottom surface, and a third step having a third diameter intermediate the first and second steps, and wherein the first cavity is located within the first step and the second cavity extends across both the first step and the second step, wherein a first portion of the second cavity is located within the first step and a second portion is located within the second step.

11. A valve spring retainer according to claim 10, wherein a first stepped region of said valve spring retainer forms the thickest part of said valve spring retainer, said first stepped region being adjacent to said central bore, and a second stepped region of said valve spring retainer forms a region adjacent to and surrounding said first stepped region, said region being thinner than said first stepped region.

12. A valve spring retainer according to claim 11, wherein a third stepped region is arranged between the second stepped region and an outer edge wall of the valve spring retainer, the third stepped region forming the thinnest portion of the valve spring retainer.

13. The valve spring retainer of claim 10, wherein the first internal cavity is disposed within a thickness of the first stepped region and includes one or more channels extending from the first internal cavity to a bottom surface of the first stepped region, and wherein the second internal cavity is disposed in a region extending across and within a thickness of both the first and second stepped regions and includes one or more channels extending from the second internal cavity to the bottom surface of the valve spring retainer.

14. The valve spring retainer of claim 13, wherein the one or more passages of the first internal cavity fluidly couple air within the first internal cavity to ambient air surrounding the valve spring retainer, and the one or more passages of the second internal cavity fluidly couple air within the second internal cavity to ambient air surrounding the valve spring retainer.

15. A valve spring retainer according to claim 8, wherein the valve spring retainer is manufactured by additive manufacturing.

Technical Field

The present description generally relates to a retainer for retaining a poppet valve spring.

background

The camshaft of the valvetrain may control the motion of lift valves, such as intake or exhaust valves in an engine. In addition to the valves and the camshaft, the valvetrain may also include rocker arms, pushrods, and lifters that couple the valves to the camshaft and convert the rotational motion of the camshaft into linear motion of the valves. The components of the valvetrain may work in concert to control the amount of air and fuel delivered to the combustion chambers during engine operation. The lift of the intake valve allows air to enter the combustion chamber through the inlet port, and when released by the cam, the intake valve may close and block the air flow. Similarly, when the exhaust valve is lifted, exhaust gas may flow from the combustion chamber to the exhaust manifold through the outlet port. The intake and exhaust valves may be fitted with valve springs to seal the valves against the valve seats when the valves are cam adjusted to a closed position.

The valve spring may be wrapped around the valve stem of the intake or exhaust valve between the cylinder head surface and the valve spring retainer. In an overhead camshaft orientation, the valve may be depressed by the cam, compressing the valve spring and opening the valve. When closed, the spring load of the valve spring applies pressure against the cylinder head surface and against the valve spring retainer to press the valve against the valve seat and block flow through the inlet or outlet port of the cylinder. To counteract the spring load of the valve spring, a valve spring retainer may be disposed along the valve stem at the opposite end of the valve from the valve seat so that the valve spring retainer does not displace against the force exerted by the valve spring. In this manner, the valve spring retainer may be anchored along the valve, and expansion of the valve spring forces the valve to slide upward to the closed position.

The spring load of the valve spring may depend on the total mass of the valve train. The components of the valve train, including the valve spring retainer, are typically made of a durable, heat resistant material such as steel. However, forming the valve train parts from metal may result in a heavy mass of the valve train, and the spring load of the valve spring may increase accordingly to maintain contact between the valve and the cam lobe of the camshaft. This may also increase friction within the valve mechanism and lead to component degradation. Specifically, positioning a valve spring retainer on top of the stem of an intake or exhaust valve may increase the stress on the valve.

Attempts to reduce the weight of the valve train include reducing the mass of the valve spring retainer. Black shows an example approach in U.S.4,321,894. A valve spring retainer is disclosed having a base including an aperture. The base also has a lip projecting downward to fit over and retain the valve spring. The valve spring retainer also includes a valve adjuster cap having threads that engage the threads in the base. Both the base and the regulator cap are formed of thinner surfaces and less material than conventional solid valve spring retainers. Thus, the total mass of the valve spring retainer is reduced.

However, the inventors herein have recognized potential issues with such systems. As one example, forming the valve spring retainer from two separate pieces (e.g., the base and the regulator cap) increases the number of pieces to be manufactured, thereby increasing production costs. In addition, by doubling the number of parts of the valve spring retainer, the labor and assembly time to manufacture the valve spring retainer is increased.

Disclosure of Invention

In one example, the above problem may be solved by a valve train of an engine, comprising: a valve spring; a disc valve spring retainer having a central bore and a plurality of internal cavities concentric with the central bore, the retainer engaging a first end of the valve spring. In this way, the valve spring retainer may be manufactured in a cost-effective manner as a single, unitary component of reduced mass.

As an example, the valve spring retainer may be fitted to an internal cavity such that the valve spring retainer is at least partially hollow. The internal cavity may form an air ring within the thickness of the valve spring retainer, wherein air within the cavity is coupled to air surrounding the valve spring retainer through a passage. Due to the hollow configuration, the amount of metal used to form the valve spring retainer is significantly reduced without affecting the structural integrity of the valve spring retainer. The holder may be manufactured as a single unit by additive manufacturing, thereby reducing production labor and time.

It should be understood that the summary above is provided to introduce in simplified form some concepts that are further described in the detailed description. This is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

Drawings

FIG. 1 illustrates an exemplary engine system in which an air door spring retainer may be used.

Fig. 2A shows a first cross-sectional view of a valve train with a valve adjusted to a closed position, the valve fitting a valve spring retainer.

Fig. 2B shows a second cross-sectional view of the valve train with the valve adjusted to an open position, the valve fitting a valve spring retainer.

Fig. 3 shows a first cross section of the hollow valve spring retainer from an isometric perspective.

Fig. 4 shows a second cross section of the hollow valve spring retainer from a front view.

Fig. 5 shows a third cross section of the hollow valve spring retainer from the bottom view.

Figures 3 to 5 are shown substantially to scale.

Detailed Description

The following description relates to a hollow valve spring retainer for a poppet valve assembly. The valve spring retainer may be included in a valvetrain of an engine system, such as the engine system shown in FIG. 1. The positioning of the valve spring retainer relative to the stem of a poppet valve (such as an intake or exhaust valve of a combustion chamber) and the valve spring is shown in the cross-sectional views of fig. 2A and 2B. The poppet valve is shown in a closed position in fig. 2A and in an open position in fig. 2B to illustrate how the valve spring retainer may assist in valve movement. Further, the positioning of the poppet valve assembly at the port of the combustion chamber may allow the poppet valve assembly to control the flow of air into the combustion chamber or the flow of exhaust gas out of the combustion chamber. Fig. 3 to 5 depict cross sections of the hollow valve spring retainer from different views and planes, showing details of the internal cavity of the hollow valve spring retainer, which may lead to a reduction of the mass of the hollow valve spring retainer.

Fig. 2A-5 illustrate an exemplary configuration with relative positioning of various components. In at least one example, if shown as being in direct contact or directly coupled to each other, these elements may be referred to as being in direct contact or directly coupled, respectively. Similarly, elements shown as being continuous or adjacent to one another may be continuous or adjacent to one another, respectively, at least in one example. As one example, components placed in coplanar contact with each other may be referred to as coplanar contacts. As another example, in at least one instance, elements positioned apart from one another with only a spacing therebetween and no other elements may be referred to as such. As yet another example, elements shown above/below each other, on opposite sides of each other, or on left/right sides of each other may be referred to as such with respect to each other. Further, as shown, in at least one example, the topmost element or the topmost point of an element may be referred to as the "top" of the component, and the bottommost element or the bottommost point of an element may be referred to as the "bottom" of the component. As used herein, top/bottom, upper/lower, above/below may be relative to a vertical axis of the figures, and are used to describe the positioning of elements of the figures relative to one another. Thus, in one example, elements shown as being above other elements are positioned vertically above the other elements. As yet another example, the shapes of elements depicted in the figures may be referred to as having those shapes (e.g., like rounded, rectilinear, planar, curved, rounded, chamfered, angled, etc.). Further, in at least one example, elements that are shown as intersecting one another can be referred to as intersecting elements or intersecting one another. Further, in one example, an element shown as being within another element or shown as being external to another element may be referred to as such.

Vehicles may include an engine system including an engine coupled between an intake system and an exhaust system. Vehicle motion may be propelled by combustion of air and fuel at combustion chambers (e.g., cylinders) of the engine. The flow of air from the intake system to the combustion chamber and the delivery of exhaust gas from the combustion chamber to the exhaust system may be controlled by adjusting intake and exhaust valves at the cylinders. An example of a vehicle having such components is shown in fig. 1. Fig. 1 depicts an example of a cylinder of an internal combustion engine 10 comprised by an engine system 7 of a vehicle 5. Engine 10 may be controlled at least partially by a control system including controller 12 and by input from a vehicle operator 130 via an input device 132. In this example, the input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. Cylinder 14 of engine 10 (which may be referred to herein as a "combustion chamber") may include combustion chamber walls 136 with a piston 138 positioned therein. Piston 138 may be coupled to crankshaft 140 such that reciprocating motion of the piston is translated into rotational motion of the crankshaft. Crankshaft 140 may be coupled to at least one drive wheel of a passenger vehicle via a transmission system. Further, a starter motor (not shown) may be coupled to crankshaft 140 via a flywheel to enable a starting operation of engine 10.

Cylinder 14 may receive intake air via a series of intake passages 142, 144, and 146. Intake passage 146 may communicate with other cylinders of engine 10 in addition to cylinder 14. FIG. 1 shows engine 10 configured with a turbocharger 175 including a compressor 174 disposed between intake passages 142 and 144, and an exhaust turbine 176 disposed along an exhaust system between exhaust manifold 148 and exhaust pipe 158. Compressor 174 may be mechanically coupled to turbine 176 via a shaft 180. The rotational speed of compressor 174 may be regulated by a wastegate 181 disposed in the exhaust system of engine system 7. In some examples, the turbocharger 175 may be an electric turbocharger and powered at least in part by an electric motor.

A Charge Air Cooler (CAC)160 may be positioned in intake passage 142 downstream of compressor 174 and upstream of throttle 162. The CAC 160 may be an air-to-air CAC or a liquid-cooled CAC configured to cool and increase the density of air compressed by the compressor 174. The cooled air may be delivered to engine 10 and combusted at cylinders 14.

A throttle 162 including a throttle plate 164 may be disposed along an intake passage of the engine to vary the flow rate and/or pressure of intake air provided to the engine cylinders. For example, throttle 162 may be positioned downstream of compressor 174, as shown in FIG. 1, or alternatively, may be positioned upstream of compressor 174.

Each cylinder of engine 10 may include one or more intake valves and one or more exhaust valves. For example, the cylinder 14 is shown to include at least one intake poppet valve 150 and at least one exhaust poppet valve 156 located at an upper region of the cylinder 14. In some examples, each cylinder of engine 10 (including cylinder 14) may include at least two intake poppet valves and at least two exhaust poppet valves located at an upper region of the cylinder.

Intake valve 150 may be controlled by controller 12 via actuator 152. Similarly, exhaust valve 156 may be controlled by controller 12 via actuator 154. During some conditions, controller 12 may vary the signals provided to actuators 152 and 154 to control the opening and closing of the respective intake and exhaust valves. The position of intake valve 150 and exhaust valve 156 may be determined by respective valve position sensors (not shown). The valve actuators may be electrically actuated or cam actuated or a combination thereof. The intake and exhaust valve timing may be controlled simultaneously, or any of the possibilities of variable intake cam timing, variable exhaust cam timing, dual independent variable cam timing, or fixed cam timing may be used. Each cam actuation system may include one or more cams and may utilize one or more of Cam Profile Switching (CPS), Variable Cam Timing (VCT), Variable Valve Timing (VVT), and/or Variable Valve Lift (VVL) systems that may be operated by controller 12 to vary valve operation. For example, cylinder 14 may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation including CPS and/or VCT. In other examples, the intake and exhaust valves may be controlled by a common valve actuator or actuation system or a variable valve timing actuator or actuation system.

In some examples, the intake valve 150 and the exhaust valve 156 may each include a valve spring 153, the valve spring 153 applying a compressive force against a surface of the cylinder 14 to seal the valve against the inlet port and the exhaust port of the cylinder 14 when the valve is actuated to the closed position. The valve spring 153 may be wound around the stems of the intake valve 150 and the exhaust valve 156. The valve spring retainer 155 may be positioned directly above the valve spring 153 at the top of each of the intake and exhaust valves 150, 156 and may be used to anchor the position of the top end of the valve spring 153 along the valve. In this manner, the valve spring retainer enables the valve spring position to be maintained along the valve stem. An exemplary embodiment of a hollow valve spring retainer is shown in fig. 2A-5 and will be described in further detail below.

Cylinder 14 may have a compression ratio, which is the ratio of the volume when piston 138 is at bottom center to top center. In one example, the compression ratio is in the range of 9:1 to 10: 1. However, in some examples where different fuels are used, the compression ratio may be increased. This may occur, for example, when higher octane fuels or fuels with higher latent enthalpy of vaporization are used. The compression ratio may also be increased if direct injection is used for its effect on engine knock.

In some examples, each cylinder of engine 10 may include a spark plug 192 for initiating combustion. Ignition system 190 can provide an ignition spark to cylinder 14 via spark plug 192 in response to spark advance signal SA from controller 12, under selected operating modes. However, in some embodiments, spark plug 192 may be omitted, such as where engine 10 may initiate combustion by auto-ignition or by injection of fuel (as may be the case with some diesel engines).

In some examples, each cylinder of engine 10 may be configured with one or more fuel injectors to provide fuel thereto. As a non-limiting example, cylinder 14 is shown to include two fuel injectors 166 and 170. Fuel injectors 166 and 170 may be configured to deliver fuel received from fuel system 8. The fuel system 8 may include one or more fuel tanks, fuel pumps, and fuel rails. Fuel injector 166 is shown coupled directly to cylinder 14 for injecting fuel directly therein in proportion to the pulse width of signal FPW-1 received from controller 12 via electronic driver 168. In this manner, fuel injector 166 provides what is known as direct injection (hereinafter "DI") to inject fuel into combustion cylinder 14. While FIG. 1 shows injector 166 positioned to one side of cylinder 14, it may alternatively be located overhead of the piston, such as near spark plug 192. Such a location may improve mixing and combustion when operating an engine with an alcohol-based fuel due to the lower volatility of some alcohol-based fuels. Alternatively, the injector may be located overhead and near the intake valve to improve mixing. Fuel may be delivered to fuel injector 166 from a fuel tank of fuel system 8 via a high pressure fuel pump and fuel rail. Further, the fuel tank may have a pressure sensor that provides a signal to controller 12.

Fuel injector 170 is shown disposed in intake passage 146 rather than cylinder 14, and is configured to provide so-called port fuel injection (hereinafter "PFI") to inject fuel into the intake port upstream of cylinder 14. Fuel injector 170 may inject fuel received from fuel system 8 in proportion to the pulse width of signal FPW-2 received from controller 12 via electronic driver 171. Note that a single driver 168 or 171 may be used for both fuel injection systems, or as depicted, multiple drivers may be used, such as driver 168 for fuel injector 166 and driver 171 for fuel injector 170.

in an alternative example, each of fuel injectors 166 and 170 may be configured as a direct fuel injector for injecting fuel directly into cylinder 14. In yet another example, each of fuel injectors 166 and 170 may be configured as a port fuel injector for injecting fuel upstream of intake valve 150. In still other examples, cylinder 14 may include only a single fuel injector configured to receive different relative amounts of different fuels from the fuel system as a fuel mixture and further configured to inject the fuel mixture directly into the cylinder as a direct fuel injector or upstream of the intake valve as a port fuel injector.

During a single cycle of the cylinder, fuel may be delivered to the cylinder through both injectors. For example, each injector may deliver a portion of the total fuel injection combusted in cylinder 14. Further, the distribution and/or relative amount of fuel delivered from each injector may vary with operating conditions (such as engine load, knock, and exhaust temperature), such as described below. Port injected fuel may be delivered during an open intake valve event, a closed intake valve event (e.g., substantially before the intake stroke), and during open and closed intake valve operation. Similarly, for example, directly injected fuel may be delivered during the intake stroke and partially during the previous exhaust stroke, during the intake stroke, and partially during the compression stroke. Thus, even for a single combustion event, the injected fuel may be injected from the port injector and the direct injector at different timings. Further, multiple injections of delivered fuel per cycle may be performed for a single combustion event. Multiple injections may be performed during a compression stroke, an intake stroke, or any suitable combination thereof.

The operation of the intake valve 150 will now be described in more detail. The intake valve 150 may be moved from a fully open position to a fully closed position, or to any position therebetween. Assuming all other conditions and parameters are constant (e.g., for a given throttle position, vehicle speed, manifold pressure, etc.), the fully open position of the valve allows more air to enter cylinder 14 from intake passage 146 than any other position of intake valve 150. Conversely, the fully closed position may prevent airflow (or allow a minimum amount of air) from entering cylinder 14 from intake passage 146 as compared to any other position of intake valve 150. Thus, positions between the fully open and fully closed positions may allow different amounts of air to flow between intake passage 146 and cylinder 14. In one example, moving intake valve 150 to a more open position allows more air to flow from intake passage 146 to cylinder 14 than its initial position.

The exhaust valve 156 may also be moved from a fully open position to a fully closed position, or to any position therebetween. Adjusting the exhaust valve 156 to a fully open position allows more exhaust gas from the cylinder 14 to enter the exhaust manifold 148 than any other position of the exhaust valve 156. When the exhaust valve 156 is in a fully closed position, exhaust gas may be blocked from flowing from the cylinder 14 to the exhaust manifold 148. Thus, positions between the fully open and fully closed positions may allow different amounts of exhaust gas to flow from the cylinders 14 to the exhaust manifold 148, or remain in the cylinders as residuals.

Fuel injectors 166 and 170 may have different characteristics. These different characteristics include size differences, for example, one injector may have a larger injection orifice than another injector. Other differences include, but are not limited to, different injection angles, different operating temperatures, different orientations, different injection timings, different injection characteristics, different locations, and the like. Further, depending on the distribution ratio of the fuel injected between injectors 170 and 166, different effects may be achieved.

The fuel tanks in fuel system 8 may contain fuels of different fuel types, such as fuels having different fuel qualities and different fuel compositions. These differences may include different alcohol content, different water content, different octane number, different heat of vaporization, different fuel blends, and/or combinations thereof, and the like. One example of fuels with different heat of vaporization may include gasoline as the first fuel type with a lower heat of vaporization and ethanol as the second fuel type with a greater heat of vaporization. In another example, an engine may use gasoline as the first fuel type and an alcohol-containing fuel blend, such as E85 (approximately 85% ethanol and 15% gasoline) or M85 (approximately 85% methanol and 15% gasoline), as the second fuel type. Other possible substances include water, methanol, mixtures of alcohols and water, mixtures of water and methanol, mixtures of alcohols, and the like.

As the mixture of intake air and fuel is combusted at the cylinders 14, exhaust valves 156 may be commanded to open and allow exhaust gas to flow from the cylinders 14 to the exhaust manifold 148. The opening of the exhaust valve 156 may be timed to open before the intake valve 150 is fully closed such that there is an overlap period when both valves are at least partially open. The overlap may create a weak vacuum that accelerates the air-fuel mixture into the cylinder, such as exhaust scavenging. The period of valve overlap may be timed in response to engine speed, camshaft valve timing, and exhaust system configuration. Exhaust manifold 148 may receive exhaust gases from other cylinders of engine 10 in addition to cylinder 14. Exhaust gas directed from cylinders 14 to exhaust manifold 148 may flow to turbine 176 or bypass turbine 176 via bypass passage 179 and wastegate 181.

When wastegate 181 is closed, exhaust gas directed to turbine 176 may drive rotation of turbine 176, thereby rotating compressor 174. Alternatively, when wastegate 181 is at least partially open, such as adjusted to a position between fully closed and fully open, or fully open, a portion of the exhaust gas may be diverted around turbine 176 via bypass passage 179. Splitting the exhaust flow through bypass passage 179 may reduce the rotation of turbine 176, thereby reducing the amount of boost provided by compressor 174 to the intake air in intake passage 142. Thus, during an event where a rapid decrease in boost is desired, such as a tip-out at input device 132, turbine 176 may be slowed by opening wastegate 181 and reducing the amount of exhaust gas directed to turbine 176.

A wastegate 181 is disposed in the bypass passage 179, the bypass passage 179 coupling the exhaust manifold 148, the downstream exhaust gas sensor 128, to the exhaust pipe 158 between the turbine 176 and the emission control device 178. Exhaust gases from turbine 176 and exhaust gases directed through bypass passage 179 may be collected in exhaust pipe 158 upstream of emission control device 178 and then catalytically treated at emission control device 178.

Exhaust gas sensor 128 is shown coupled to exhaust manifold 148 upstream of turbine 176 and to the junction between bypass passage 179 and exhaust manifold 148. For example, sensor 128 may be selected from a variety of suitable sensors to provide an indication of exhaust gas air/fuel ratio, such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a two-state oxygen sensor or EGO (as depicted), a HEGO (heated EGO), a NOx, HC, or CO sensor, which is then processed at emission control device 178. Emission control device 178 may be a Three Way Catalyst (TWC), NOx trap, various other emission control devices, or combinations thereof, configured to remove unwanted chemicals from exhaust gas prior to releasing it to the atmosphere.

The valves and other actuatable components of the vehicle 5 described above may be controlled by the controller 12. The controller 12 is shown in fig. 1 as a microcomputer that includes a microprocessor unit 106, an input/output port 108, an electronic storage medium, shown in this particular example as a non-transitory read-only memory chip 110 for storing executable instructions, for executable programs and calibration values, a random access memory 112, a keep alive memory 114, and a data bus. Controller 12 may receive various signals from various sensors coupled to engine 10 depicted in fig. 1, as well as sensor 16 shown and described in fig. 2A-2B. In addition to those signals previously discussed, the controller may also receive various signals, including the following measurements: intake Mass Air Flow (MAF) from mass air flow sensor 122; engine Coolant Temperature (ECT) from temperature sensor 116 coupled to cooling sleeve 118; a surface ignition pickup signal (PIP) from Hall effect sensor 120 (or other type) coupled to crankshaft 140; a Throttle Position (TP) from a throttle position sensor; and a manifold absolute pressure signal (MAP) from sensor 124. Engine speed signal, RPM, may be generated by controller 12 from signal PIP. Manifold pressure signal MAP from a manifold pressure sensor may be used to provide an indication of vacuum or pressure in the intake manifold. The exhaust manifold pressure may be measured by a pressure sensor 182 and the pressure in the exhaust pipe 158 measured by another pressure sensor 184. Controller 12 may infer the engine temperature based on the engine coolant temperature.

As described above, FIG. 1 shows only one cylinder in a multi-cylinder engine. Thus, each cylinder may similarly include its own set of intake/exhaust valves, fuel injectors, spark plugs, and the like. It should be appreciated that engine 10 may include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12, or more cylinders. Further, each of these cylinders may include some or all of the various components described and depicted with respect to cylinder 14 by FIG. 1.

In some examples, the vehicle 5 may be a hybrid vehicle having multiple torque sources available for one or more wheels 55. In other examples, the vehicle 5 is a conventional vehicle having only an engine. In the illustrated example, the vehicle 5 includes an engine 10 and a motor 52. The electric machine 52 may be a motor or a motor/generator. When the one or more clutches 56 are engaged, the crankshaft 140 of the engine 10 and the motor 52 are connected to the wheels 55 via the transmission 54. In the depicted example, the first clutch 56 is disposed between the crankshaft 140 and the motor 52, and the second clutch 56 is disposed between the motor 52 and the transmission 54. Controller 12 may send signals to an actuator of each clutch 56 to engage or disengage the clutch to connect or disconnect crankshaft 140 from motor 52 and components connected thereto, and/or to connect or disconnect motor 52 from transmission 54 and components connected thereto. The transmission 54 may be a gearbox, a planetary gear system, or another type of transmission. The powertrain may be configured in various ways, including, for example, a parallel, series, or series-parallel hybrid vehicle.

The electric machine 52 receives electrical power from an energy storage device 58 (herein a battery 58) to provide torque to the wheels 55. The motor 52 may also operate as a generator to provide electrical power to charge the battery 58, such as during braking operations.

The controller 12 receives signals from the various sensors of fig. 1 and 2A-2B and, based on the received signals and instructions stored in the controller's memory, regulates engine operation using the various actuators of fig. 1 and 2A-2B. For example, the controller may use the PIP signal and information from a position sensor of intake valve 150 to determine fuel injection timing. As another example, signals from position sensors of the intake valve 150 and the exhaust valve 156 may be used to adjust spark timing.

The opening and closing of intake and/or exhaust valves (hereinafter collectively referred to as valves) may affect engine operation, such as spark timing, fuel injection timing, as described above, as well as power output and performance of the engine. Ensuring that the valve seals against the intake or exhaust port of the cylinder when the valve is closed may reduce the likelihood that the air-fuel ratio deviates from a target air-fuel ratio (e.g., stoichiometric) during combustion. Adapting the valve to the valve spring may improve the sealing engagement of the valve with the intake or exhaust port. In order to keep the required compression force on the valve by the valve spring so that the valve is pressed firmly against the port, the valve may further comprise a valve spring retainer. The valve spring retainer may be disposed directly above and in contact with the top end of the valve spring and may resist displacement along the valve. The positioning of the valve spring retainer is shown in greater detail in fig. 2A-2B in a partial cross-sectional view of the valve train 202.

Valvetrain 202 may include one or more camshafts equipped with camshaft lobes to control the position of the intake and exhaust valves of the cylinders. A dual overhead camshaft arrangement is shown in the example of fig. 2A-2B, but other examples may include alternate positioning of camshafts, such as a single overhead camshaft or a pushrod system where the camshaft is disposed below the intake and exhaust valves. A first cross-sectional view 200 of the valve train 202 is shown in fig. 2A with the valve 204 in a closed position. The valve 204 may be the intake valve 150 or the exhaust valve 156 of FIG. 1, and may be disposed in a cylinder head 206 of a cylinder 207. The cam lobe 208 rotating about the camshaft 203 may be positioned above the cylinder head 206 and may be one of a plurality of cam lobes attached to the camshaft 203. The cam lobe 208 may have an elongated tapered end 210 and a rounded end 212. In the first cross-sectional view 200, the cam lobe 208 is shown rotated to a position such that the rounded end 212 contacts a cam follower 214 disposed at an upper end 216 of the valve 204. The cam follower 214 may be shaped as a cap that surrounds an upper end 216 of the valve 204.

The valve 204 may extend between the cam lobe 208 and a port 224, which port 224 may be an intake port or an exhaust port. The port 224 is fluidly coupled to the cylinder 207, and the flange 226 of the valve 204 is disposed at the merging region 215 of the port 224 and the cylinder 207. The diameter of the flange 226 may be at least equal to or slightly larger than the diameter of the port 224 in the merge area 215, such that when the valve 204 is closed, as shown in FIG. 2A, flow between the port 224 and the cylinder 207 is blocked.

the valve 204 may move up or down relative to the area where the port 224 and cylinder 207 merge. The motion is controlled by converting the rotation of the cam lobes 208, which are actuated by the rotation of the camshaft 203, into linear motion of the valves 204. For example, in fig. 2A, the cam lobe 208 rotates such that a circular end 212, having a smaller diameter relative to the camshaft 203 than the tapered end 210, contacts the spacer 218. In this position, the valve 204 may be lifted in the direction indicated by arrow 228 such that the flange 226 seals the port 224 from the cylinder 207. When the cam lobe 208 rotates to the position shown in FIG. 2A, the lift of the valve 204 may be assisted by a valve spring 230.

Valve spring 230 wraps around a stem 232 of valve 204, extending between a surface of cylinder head 206 and a valve spring retainer 234. The valve spring retainer 234 may be generally disc-shaped with the valve stem 232 inserted through a central bore of the valve spring retainer 234. The valve spring retainer 234 may be in a fixed position along the valve stem 232. That is, the valve spring retainer 234 does not slide along the valve stem 232, which in some examples may be accomplished as follows: valve spring retainer 234 is welded to valve stem 232 such that valve spring retainer 234 is secured to valve stem 232 by a weld joint. Other coupling configurations are also possible. When the valve 204 is in the raised position, the distance the cam follower 214 is depressed decreases relative to the distance the tapered end 210 contacts the pad 218 of the cam follower 214, as shown in fig. 2B. The compression of the valve spring 230 is reduced and the release of at least a portion of the spring load of the valve spring 230 causes the valve spring 230 to expand along the length of the valve stem 232. The bottom end 236 of the valve spring 230 presses against the surface of the cylinder head 206, while the top end 238 of the valve spring 230 presses against the valve spring retainer 234 as the valve spring 230 expands. As a result, the valve 204 slides upward, and contact of the flange 226 against the valve seat 240 stops the upward movement, the valve seat 240 being shown in FIG. 2B. In this position, the valve 204 is closed.

In a second cross-sectional view 250 shown in fig. 2B, cam lobe 208 is rotated such that tapered end 210 of cam lobe 208 is in contact with washer 218 of cam follower 214. The cam follower 214 is depressed in the direction indicated by arrow 242 relative to the position of the cam follower 214 shown in fig. 2A. Depression of the cam follower 214 causes the valve 204 to also slide in the direction indicated by arrow 242 and the flange 226 of the valve 204 to displace under the valve seat 240 such that flow between the port 224 and the cylinder 207 is no longer blocked by the valve 204. In this position, the valve 204 is open.

It should be understood that the closed and open positions of fig. 2A and 2B, respectively, represent the boundaries of motion of the valve 204. In other words, the positions of the valves 204 in fig. 2A and 2B show the fully closed orientation and the fully open orientation, respectively. The valve 204 may continuously slide through a range of positions between fully open and fully closed as the cam lobe 208 rotates such that the surface of the cam lobe 208 between the central region of the rounded end 212 (shown in fig. 2A) and the central region of the tapered end 210 (shown in fig. 2B) contacts the pad 218 of the cam follower 214.

In the open position, the valve spring 230 may be compressed between the valve spring retainer 234 and a surface of the cylinder head 206. The valve spring retainer may be formed of a durable, rigid material having a relatively high heat resistance, such as steel. Depending on the number of cylinders present, the engine system may include a plurality of valve spring retainers. In a performing vehicle having a larger number of cylinders, the number of valve spring retainers may be correspondingly increased, resulting in an undesirable increase in the weight of the valve train. Thus, the use of a reduced mass valve spring retainer may offset the reduction in engine performance caused by the weight of the valve spring retainer. The mass of the valve spring retainer may be reduced by introducing an internal cavity, thereby reducing the amount of material used to form the valve spring retainer. Nevertheless, the hollow valve spring retainer is still able to maintain tensile strength and resist deformation caused by the pressure exerted by the valve spring on the valve spring retainer.

The hollow valve spring retainer may be manufactured by additive manufacturing, such as 3D printing. The additive manufacturing of the valve spring retainer may allow the retainer to be easily formed with a relatively thin continuous surface, as compared to conventional methods of forming the valve spring retainer (e.g., die casting). The material wasted in the manufacturing process is reduced and the production labor is relatively reduced, thereby reducing the cost. Further, the reduction in tooling costs may at least partially balance forming the hollow valve spring retainer from a more expensive metal, such as titanium or nickel-chromium alloy. Also, 3D printing of the valve spring retainer may allow for the use of alternative lightweight materials, such as low density aluminum alloys, that are difficult to use in conventional machining methods.

A first cross-section 300 of a hollow valve spring retainer 302 is shown from the perspective of fig. 3. A set of reference axes 301 (representing the y-axis, z-axis and x-axis) are provided for comparison between the views shown in fig. 3-5. The first cross-section 300 is taken along the z-y plane. The valve spring retainer 302 has a central axis 304 that is coaxial with the z-axis. Elements common between the views of the valve spring retainer 302 depicted in fig. 3-5 are labeled similarly for the sake of brevity and will not be re-introduced outside of the initial description for the sake of brevity.

The hollow valve spring retainer 302 may be configured as a disk or solid ring having a central circular aperture 310. The outer diameter 303 of the valve spring retainer at the rim wall 332 is larger than the inner diameter 305 of the valve spring retainer at the bore wall 311. The disc may have a flat upper face 312 and a stepped lower face 314 comprising a plurality of concentric sections (e.g., concentric with the central bore 310), each section having a different thickness. Each concentric section is distinguished from an adjacent section by the stepped geometry of lower face 314, wherein each section is separated from an adjoining section by a substantially perpendicular adjacent surface. The section near the bore wall 311 forms the thickest region of the valve spring retainer 302, where the thickness 306 is measured along the z-axis. Each concentric section disposed outside of the inner adjacent section (e.g., further from the bore wall 311 and closer to the edge wall 332) is thinner than the inner section. Thus, the outermost section proximate the edge wall 332 may form the thinnest portion of the valve spring retainer 302. It should be understood that while the valve spring retainer shown in fig. 3-5 is shown with three stepped sections, other examples of valve spring retainers may have more or less than three sections, and the transition between sections may be more gradual. For example, instead of forming sections of different steps of different thicknesses, the thickness of the valve spring retainer may gradually decrease from the bore wall 311 to the rim wall 221.

The thickness 306 (at the thickest region of the valve spring retainer 302 near the bore 310) is the distance between the upper face 312 and the lower face 314, which is less than the radius 308 of the valve spring retainer 302. A circular aperture 310 extends through the entire thickness 306 of the valve spring retainer 302, through a central region of the valve spring retainer 302. The central shaft 304 may be centered within a circular aperture 310, the central shaft 304 extending along the thickness 306 of the thickest section of the valve spring retainer 302. The aperture wall 311 may have a flat surface that is slightly angled with respect to the central axis 304. The angle of the plane of the bore wall 311, as shown in the second cross-section 400 of the valve spring retainer 302 in fig. 4 (also taken along the z-y plane), may result in the diameter of the bore at the upper face 312 of the valve spring retainer 302 being greater than the diameter of the bore 310 at the lower face 314 of the valve spring retainer 302.

The first step 316 of the lower face 314 of the valve spring retainer 302 may be disposed at the innermost edge of the valve spring retainer 302, immediately adjacent to and surrounding the bore 310. The third step 328 is disposed at the outermost edge of the valve spring retainer 302, inward of the edge wall 332, and the second step 318 is positioned between the first step 316 and the third step 328. The first step 316 may form a portion of the radius 308 of the valve spring retainer 302 that represents the thickest (e.g., having the thickness 306) portion of the valve spring retainer 302. The first step 316 may extend circumferentially around the bore 310 and have a width, measured along the y-axis, that is at least one-third of the overall radius 308 of the valve spring retainer 302. The bottom surface 315 of the first step 316 may be parallel to the upper face 312 of the valve spring retainer 302, and the sidewall 317 of the first step 316 may be substantially perpendicular to the bottom surface 315.

The first step 316 may be circumferentially surrounded by a second step 318 having a thickness 320 that is thinner than the thickness 306 of the first step 316. The bottom surface 315 of the first step 316 extends into the sidewall 317 of the first step 316 along the outer circumference of the first step 316. Additionally, the side wall 317 of the first step may extend into the bottom surface 322 of the second step 318, with the bottom surface 322 parallel to the upper face 312 of the valve spring retainer 302. The bottom surface 322 of the second step 318 may extend into a sidewall 324 of the second step 318, the sidewall 324 being perpendicular to the bottom surface 322 of the second step 318 of the valve spring retainer 302. The sidewall 324 may be the outer circumference of the second step 318. The width of the second step 318 defined along the y-axis may be one-third or less of the radius 308 of the valve spring retainer 302. The side wall 324 of the second step 318 may be coupled to a bottom surface 326 of a third step 328, the bottom surface 326 also being parallel to the upper face 312 of the valve spring retainer 302.

The third step 328 may circumferentially surround the second step 318 and may be the thinnest section of the valve spring retainer 302 having a thickness 330. The thickness 330 of the third step 328 is less than the thicknesses 320, 306 of the second step 318 and the first step 316, respectively, wherein the thickness 320 of the second step 316 is intermediate the thickness 306 of the first step 316 and the thickness 330 of the third step 328. The width of the third step 328 defined along the y-axis may account for one-third or less of the radius 308 of the valve spring retainer 302. The third step 328 may also be the outermost section of the valve spring retainer 302, which is surrounded by an edge wall 332. The overall width of the valve spring retainer 302 is the sum of the widths of each of the first section 316, the second section 318, and the third section 328, and the overall height of the valve spring retainer 302, defined along the z-axis, is the thickness 306 of the first step 316. Edge wall 332 is parallel to the z-axis and is coupled to upper face 312 by a bevel 334 that is inclined relative to the z-axis. In other examples, the edge wall 332 may be coupled to the upper face 312 by a chamfered surface.

The stepped geometry of the lower face 314 of the valve spring retainer 302 may allow a valve spring (such as the valve spring 230 shown in fig. 2A-2B) to be retained by the valve spring retainer 302. For example, the top end of the valve spring may engage the lower face 314 by wrapping around the side wall 324 of the second step 318 and nesting against the bottom surface 326 of the third step 328. Alternatively, depending on the diameter of the valve spring, the tip of the valve spring may nest against the bottom surface 322 of the second step 318 and wrap around the sidewall 317 of the first step 316. Thereby, the position of the tip end of the valve spring is held by the valve spring holder 302.

To reduce the mass of the valve spring retainer 302, the valve spring retainer 302 may be at least partially hollow by configuring the valve spring retainer 302 with multiple internal cavities in addition to the central bore 310. The first cavity 336 is shown in fig. 3-5 as being disposed within the thickness 306 of the first step 316 of the valve spring retainer 302. A cross-section of the first cavity 336 taken along a z-y plane or a z-x plane may have a circular irregular geometry. The first cavity 336 may be coaxial with the valve spring retainer 302, e.g., the central axis 304 of the valve spring retainer 302 is also the central axis of the first cavity 336 and may form a continuous circular passage extending through the first step 316 of the valve spring retainer 302.

The first cavity 336 may have a top surface or top 338 that may be curved upward, as shown in fig. 3 and 4. The top 338 may be tapered, having a width defined along the y-direction that is narrowest at the top of the top 338 and widest where the top is coupled to the sidewall 340 of the first cavity 336. However, in other examples, the top 338 of the first cavity 336 may be coplanar with the upper face 312 of the valve spring retainer 302. The top 338 may be coupled to the top end of a sidewall 340 of the first cavity 336 that is straight and substantially coplanar with the aperture wall 311. The bottom end of the sidewall 340 may be coupled to a bottom surface or bottom 342 of the first cavity 336. The bottom portion 342 may curve downward in a direction opposite the curvature of the top portion 338 of the first cavity 336 and may curve without tapering. The bottom 342 may include at least one channel 344 that extends from the bottom 342 of the first cavity 336 to the bottom surface 315 of the first step 316.

The passage 344 may be a passage for exchanging air between the first cavity 336 and the ambient environment of the valve spring retainer 302. In one example, the channel 344 may have a circular cross-section taken along the y-x plane that fluidly couples air within the first cavity 336 to air surrounding, e.g., outside, the valve spring retainer 302. By configuring the first cavity 336 with at least one channel 344, the pressure that may build up within the first cavity 336 during heating of the valve spring retainer 302 may be balanced with the ambient air surrounding the valve spring retainer 302. For example, heat may be transferred from the cylinder where combustion occurs to components near or in contact with the cylinder, such as intake and exhaust valves, valve springs, and valve spring retainers. The heating of the valve spring retainer 302 may expand the air contained within the first cavity 336. Heated expanding air may be exhausted from the first cavity 336 through the passage 344, thereby reducing the force exerted on the surface of the first cavity 336 from the heated air.

While the valve spring retainer 302 of fig. 3-5 includes two passages, it should be understood that the valve spring retainer may include more or fewer passages, such as 1, 5, or 8, etc., without departing from the scope of the present disclosure. Furthermore, the example of the valve spring retainer 302 shown in fig. 3-5 is a non-limiting example, and many variations in the alignment, location, size, shape, and size of the first cavity 336 and the channel 344 have been contemplated. As one example, the first cavity 336 may not be a single continuous channel surrounding the valve spring retainer 302, but may include two or more sections surrounding the bore 310 within the first step 316 of the valve spring retainer 302.

The valve spring retainer 302 may include a second cavity 346 disposed between the first cavity 336 and the rim wall 332 of the valve spring retainer 302 and spaced apart from the first cavity 336 and the rim wall 332. The second cavity 346 may concentrically surround the first cavity 336, and both the first and second cavities 336, 346 may be concentric about the central bore 310 of the valve spring retainer 302. The second cavity 346 may be partially disposed within the thickness 306 of the first step 316 and partially extend into the thickness 320 of the second step 318. In other words, the first portion 319 of the second cavity 346 may be located within the first step 316 and the second portion 321 may be located within the second step 318, as shown in fig. 4. Since the second cavity 346 partially extends into the second step 318, which is thinner (e.g., thinner than the first step 316), the height of the second cavity 346 defined along the z-axis may be less than the height of the first cavity 336.

The cross-sectional geometry of the second cavity 346 may be irregularly shaped, as shown in fig. 3 and 4. For example, an upper surface or top 348 of the second cavity 346 can curve upward and taper such that the top of the top 348 is narrower (defined along the y-axis) than the base of the top 348, where the top 348 is coupled to the top ends of the first and second sidewalls 350, 352 of the second cavity 346. The first and second sidewalls 350, 352 may not be coplanar. In contrast, as shown in fig. 3 and 4, the first sidewall 350 of the second cavity 346 may be substantially coplanar with the sidewall 340 of the first cavity 336. However, the second sidewall 352 of the second cavity 346 may be angled relative to the first sidewall 350 and form a greater angle relative to the z-axis than the first sidewall 350. The angling of the second sidewall 352 may result in a bottom surface or bottom 354 of the second cavity 346 being wider than the top 348.

The bottom ends of the first and second sidewalls 350 and 352 may be coupled to the bottom 354 of the second cavity 346. The bottom portion 354 may curve downward in a direction opposite the curvature of the top portion 348 of the second cavity 346, and may not taper, unlike the top portion 348. The bottommost point of the bottom 354 of the second cavity 346 may be higher than the bottommost point of the bottom 342 of the first cavity 336, resulting in a smaller height of the second cavity 346, which is defined along the z-axis. Also, the cross-section of the second cavity 346 is formed by an asymmetric surface, resulting in an irregular shape of the second cavity 346. Although not shown in fig. 3 and 4, the bottom 354 of the second cavity 346 may include one or more channels, similar to the channels 344 of the first cavity 336. The placement of the channel 344 of the second cavity 346 may be offset from the placement of the channel 344 of the first cavity 336. For example, the channels of the second cavity 346 may be angled along the y-x plane relative to the x-axis such that the cross-sections 300 and 400 of fig. 3 and 4 do not separate one or more channels of the second cavity 346.

The channel 344 of the second cavity 346 may extend from a bottom 354 of the second cavity 346 to an area of the underside 314 of the valve spring retainer 302, such as the bottom surface 322 of the second step 318 of the valve spring retainer 302. The channel 344 of the second cavity 346 may fluidly couple the air within the second cavity 346 to the air surrounding the valve spring retainer 302, thereby providing one or more vents to equalize the pressure within the second cavity 346 with the ambient air surrounding the valve spring retainer 302 as the valve spring retainer 302 is heated and the air within the second cavity 346 expands.

A third cross-section 500 of the valve spring retainer 302 is shown in fig. 5, which is taken along the y-x plane. A circular extension of the first cavity 336 formed by the first step 316 through a portion of the valve spring retainer 302 is shown in the third cross-section 500 depicting the coaxial arrangement of the first cavity 336 and the valve spring retainer 302 relative to the central axis 304. Also shown is a concentric circular extension of a second cavity 346 around the first cavity 336, passing through both a portion of the first step 316 and a portion of the second step 318, wherein the second cavity 346 is spaced from the first cavity 336 by the material of the valve spring retainer 302. The second cavity 346 is positioned closer to the edge wall 332 than the first cavity 336. The top 348 of the first and second cavities 336, 346 may be coplanar, both aligned and coaxial with the y-x plane, both centered about the central axis 302.

The example of the second cavity 346 shown in fig. 3-5 is a non-limiting example of the second cavity 346, as previously described with respect to the first cavity 336 of the valve spring retainer 302, and variations in the size, shape, geometry, and continuity of the second cavity 346 have been considered. Additionally, more or fewer cavities may be provided in the valve spring retainer 302 while keeping the mass of the valve spring retainer 302 reduced and without degrading the structural integrity of the valve spring retainer 302. For example, the valve spring retainer 302 may include a single large volume cavity or 3 cavities, each having a volume less than the first and second cavities 336, 346 shown. As another example, the first cavity 336 may be a continuous channel within the valve spring retainer 302, while the second cavity 346 may be formed from two or more sections separated by the material of the valve spring retainer 302 such that the sections of the second cavity 346 are not in fluid communication with each other. Each section of the second cavity 346 may include a channel, such as the channel 344 of the first cavity 336, that provides a passage for venting inflation air from each section of the cavity to the ambient air surrounding the valve spring retainer 302. Many combinations have been envisaged, including variations in the configuration of the cavities.

In this manner, the valve spring retainer may be configured to be at least partially hollow, thereby reducing the mass of the valve spring retainer without affecting the ability of the valve spring retainer to support the valve spring. The valve spring retainer may include one or more internal cavities, forming one or more channels of space within the thickness of the valve spring retainer. The internal cavity reduces the material requirements of the valve spring retainer, reducing the associated manufacturing costs without compromising the structural integrity of the retainer. Furthermore, the internal cavity and any associated passages enable air exchange between the internal cavity and the air surrounding the valve spring retainer. This allows the pressure within the cavity to equalize with ambient air when the valve spring retainer is heated, such as during high load engine operation. The valve spring retainer may be formed from a continuous single piece of material, allowing the valve spring retainer to be manufactured as a single unit by additive manufacturing. As a result, the costs and time associated with the production of the valve spring retainer are significantly reduced. The technical effect of adapting the engine to the hollow valve spring retainer is that the overall mass of the valve train can be reduced, thereby reducing the spring load of the valve springs and reducing the friction generated between the valve train components.

In one embodiment, a valvetrain for an engine may include: a valve spring; a disc valve spring retainer having a central bore and a plurality of internal cavities concentric with the central bore, the retainer engaging a first end of the valve spring. In a first example of the valve mechanism, the plurality of internal cavities form a continuous air passage around the central bore of the valve spring retainer, each of the internal cavities further comprising a passage coupling the air passage of the respective internal cavity to ambient air surrounding the retainer. The second example of the valve train optionally includes the first example, and further comprising wherein each of the plurality of internal cavities are spaced apart from each other, separated by the material of the valve spring retainer. A third example of the valve train optionally includes one or more of the first and second examples, and further comprising wherein the plurality of internal cavities have an upwardly curved top and a downwardly curved bottom, the top and bottom of the internal cavities being coupled by a sidewall. A fourth example of the valve train optionally includes one or more of the first through third examples, and further comprising wherein the valve spring is coupled to a stem of a valve, and a position of the valve spring retainer along the stem is retained via a secure attachment of the retainer to the stem, the secure attachment comprising a weld joint. A fifth example of the valve train optionally includes one or more of the first through fourth examples, and further comprising wherein the first end of the valve spring faces away from a cylinder head, the valve spring further comprising a second end opposite the first end, the second end in contact with a surface of the cylinder head, and wherein the valve spring exerts a spring load on the valve spring retainer at the first end of the valve spring and on the surface of the cylinder head at the second end. A sixth example of the valve train optionally includes one or more of the first through fifth examples, and further comprising wherein the valve spring retainer is welded to the valve stem such that the valve spring retainer resists displacement from the valve spring and converts the spring load of the valve spring into motion of the valve. A seventh example of the valve train optionally includes one or more of the first through sixth examples, and further comprising wherein the valve spring retainer has a flat top surface and a stepped lower surface forming a thickest portion of the valve spring retainer proximate the central bore and a thinnest portion proximate an outer edge of the valve spring retainer.

As another embodiment, a hollow valve spring retainer includes: an annular unit having a central bore for receiving a valve stem; each hollow cavity is concentric with the central hole, the first cavity is positioned in the annular unit, and the distance from the central hole is different from that of the second channel. In a first example of the valve spring retainer, the central bore extends from a top surface to a bottom surface of the unit, and wherein the first cavity is positioned within the annular unit closer to the central bore and the second channel is positioned within the annular unit closer to an outer edge wall of the valve spring retainer. The second example of the valve spring retainer optionally includes the first example, and further includes wherein the bottom surface of the annular unit is stepped, a diameter of the annular unit at the outer rim wall being greater than a diameter at a circumference of an innermost step, the diameter decreasing in a stepwise manner from the top surface to the bottom surface. The third example of the valve spring retainer optionally includes one or more of the first and second examples, and further comprising wherein the stepped annular unit includes a first step having a first diameter at the top surface, a second step having a second diameter at the bottom surface, and a third step having a third diameter intermediate the first and second steps, and wherein the first cavity is located within the first step and the second cavity extends across both the first and second steps, wherein a first portion of the second cavity is located within the first step and a second portion is located within the second step. The fourth example of the valve spring retainer optionally includes one or more of the first through third examples, and further comprising wherein a first stepped region of the valve spring retainer forms a thickest portion of the valve spring retainer, the first stepped region being proximate the central bore. A fifth embodiment of the valve spring retainer optionally includes one or more of the first through fourth examples, and further comprising wherein the second stepped region of the valve spring retainer forms a region adjacent to and surrounding the first stepped region that is thinner than the first stepped region. A sixth example of the valve spring retainer optionally includes one or more of the first through fifth examples, and further includes wherein a third stepped region is disposed between the second stepped region and an outer edge wall of the valve spring retainer, the third stepped region forming the thinnest portion of the valve spring retainer. A seventh example of the valve spring retainer optionally includes one or more of the first through sixth examples, and further comprising wherein the first internal cavity is disposed within a thickness of the first stepped region and includes one or more channels extending from the first internal cavity to a bottom surface of the first stepped region. An eighth example of the valve spring retainer optionally includes one or more of the first through seventh examples, and further comprising wherein the second internal cavity is disposed in a region extending across and within a thickness of both the first stepped region and the second stepped region, and includes one or more channels extending from the second internal cavity to the bottom surface of the valve spring retainer. A ninth example of the valve spring retainer optionally includes one or more of the first through eighth examples, and further comprising wherein the one or more passages of the first internal cavity fluidly couple air within the first internal cavity to ambient air surrounding the valve spring retainer, and the one or more passages of the second internal cavity fluidly couple air within the second internal cavity to ambient air surrounding the valve spring retainer. A tenth example of the valve spring retainer optionally includes one or more of the first through ninth examples, and further comprising wherein the valve spring retainer is manufactured by additive manufacturing.

As another embodiment, a method includes 3D printing a hollow valve spring retainer configured with one or more concentric internal cavities concentric with a central bore of the valve spring retainer; fitting the valve train to the hollow valve spring retainer, which is coupled to the stem of the valve, is fixed to the stem by a welded joint, and is disposed above and in contact with the top end of the valve spring.

It should be noted that the exemplary control and estimation routines included herein may be used with various engine and/or vehicle system configurations. The control methods and programs disclosed herein may be stored as executable instructions in a non-transitory memory and executed by a control system, including a controller, in conjunction with various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various acts, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts, operations, and/or functions may be repeatedly performed depending on the particular strategy being used. Further, the described acts, operations, and/or functions may graphically represent code to be programmed into the non-transitory memory of the computer readable storage medium in the engine control system, with the described acts being performed by executing instructions in the system comprising the various engine hardware components in combination with the electronic controller.

It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above-described techniques may be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations and subcombinations regarded as novel and nonobvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.

According to the present invention, there is provided a valve mechanism of an engine, the valve mechanism having: a valve spring; a disc valve spring retainer having a central bore and a plurality of internal cavities concentric with the central bore, the retainer engaging a first end of the valve spring.

According to one embodiment, the plurality of internal cavities form a continuous air passage around the central bore of the valve spring retainer, each of the internal cavities further comprising a passage coupling the air passage of the respective internal cavity to ambient air surrounding the retainer.

According to one embodiment, each of the plurality of internal cavities is spaced apart from each other, separated by the material of the valve spring retainer.

According to one embodiment, the plurality of internal cavities have an upwardly curved top and a downwardly curved bottom, the top and the bottom of the internal cavities being coupled by a sidewall.

According to one embodiment, the valve spring is coupled to a stem of a valve, and the position of the valve spring retainer along the stem is retained via a secure attachment of the retainer to the stem, the secure attachment comprising a welded joint.

According to one embodiment, the first end of the valve spring faces away from a cylinder head, the valve spring further comprising a second end opposite the first end, the second end being in contact with a surface of the cylinder head, and wherein the valve spring exerts a spring load on the valve spring retainer at the first end of the valve spring and on the surface of the cylinder head at the second end.

According to one embodiment, the valve spring retainer is welded to the valve stem such that the valve spring retainer resists displacement from the valve spring and converts the spring load of the valve spring into motion of the valve.

According to one embodiment, the valve spring retainer has a flat top surface and a stepped lower surface forming the thickest part of the valve spring retainer near the central bore and the thinnest part near the outer edge of the valve spring retainer.

According to the present invention, there is provided a hollow valve spring holder having: an annular unit having a central bore for receiving a valve stem; each hollow cavity is concentric with the central hole, the first cavity is positioned in the annular unit, and the distance from the central hole is different from that of the second channel.

according to one embodiment, the central bore extends from the top face to the bottom face of the unit, and wherein the first cavity is located within the annular unit closer to the central bore and the second channel is located within the annular unit closer to the outer edge wall of the valve spring retainer.

According to one embodiment, the bottom surface of the annular unit is stepped, the diameter of the annular unit at the outer rim wall being larger than the diameter at the circumference of the innermost step, the diameter decreasing in a stepwise manner from the top surface to the bottom surface.

According to one embodiment, the stepped annular unit comprises a first step having a first diameter at the top surface, a second step having a second diameter at the bottom surface, and a third step having a third diameter intermediate the first step and the second step, and wherein the first cavity is located within the first step and the second cavity extends across both the first step and the second step, wherein a first portion of the second cavity is located within the first step and a second portion is located within the second step.

According to one embodiment, a first stepped region of the valve spring retainer forms the thickest part of the valve spring retainer, said first stepped region being close to the central bore.

According to one embodiment, the second stepped region of the valve spring retainer forms a region adjacent to and surrounding the first stepped region, said region being thinner than the first stepped region.

According to one embodiment, a third stepped region is arranged between the second stepped region and an outer edge wall of the valve spring retainer, the third stepped region forming the thinnest part of the valve spring retainer.

According to one embodiment, the first internal cavity is disposed within a thickness of the first stepped region and comprises one or more channels extending from the first internal cavity to a bottom surface of the first stepped region.

According to one embodiment, the second internal cavity is provided in a region extending across and within the thickness of both the first stepped region and the second stepped region, and comprises one or more channels extending from the second internal cavity to the bottom face of the valve spring retainer.

According to one embodiment, the one or more passages of the first internal cavity fluidly couple air within the first internal cavity to ambient air surrounding the valve spring retainer, and the one or more passages of the second internal cavity fluidly couple air within the second internal cavity to ambient air surrounding the valve spring retainer.

According to one embodiment, the valve spring retainer is manufactured by additive manufacturing.

According to the invention, a method for a valve train comprises 3D printing a hollow valve spring retainer configured with one or more concentric internal cavities concentric with a central bore of the valve spring retainer; fitting the valve train to the hollow valve spring retainer, which is coupled to the stem of the valve, is fixed to the stem by a welded joint, and is disposed above and in contact with the top end of the valve spring.