阅读说明：本技术 用于铰接式车辆的制动系统 (Brake system for articulated vehicle ) 是由 C·D·瓦伦塔 A·J·韦尔特纳 于 2020-02-06 设计创作，主要内容包括：本发明公开了一种用于铰接式车辆的制动系统。所述制动系统包括联接到牵引装置(14)的制动组件(102),所述制动组件被配置成基于液压机械压力信号(106)和机电压力信号(108)中的一个来施加制动组件压力(104)。截止阀(118)被配置成在关闭时阻止液压机械压力信号。制动控制器(120)被配置成传输被配置成关闭所述截止阀的隔离信号(122),并传输基于命令的ABS制动压力的ABS控制信号(116)。(The invention discloses a brake system for an articulated vehicle. The brake system includes a brake assembly (102) coupled to the traction device (14) configured to apply a brake assembly pressure (104) based on one of a hydro-mechanical pressure signal (106) and an electro-mechanical pressure signal (108). The shutoff valve (118) is configured to block the hydro-mechanical pressure signal when closed. A brake controller (120) is configured to transmit an isolation signal (122) configured to close the shutoff valve and transmit an ABS control signal (116) based on a commanded ABS brake pressure.)

1. A braking system (100) for an articulated vehicle (10), the braking system comprising:

a brake assembly (102) coupled to a traction device (14), the brake assembly configured to apply a brake assembly pressure (104) to reduce a rotational speed of the traction device, the brake assembly pressure based on one of a hydro-mechanical pressure signal (106) and an electro-mechanical pressure signal (108);

a hydro-mechanical brake control valve (110) configured to output a hydro-mechanical pressure signal based on a displacement of a brake pedal (112);

an electromechanical brake control valve (114) configured to output an electromechanical pressure signal based on an anti-lock brake system (ABS) control signal (116);

a shutoff valve (118) configured to allow the hydro-mechanical pressure signal to control the brake assembly pressure when the shutoff valve is open and to prevent the hydro-mechanical pressure signal from controlling the brake assembly pressure when the shutoff valve is closed; and

a brake controller (120) configured to:

determining a target bend speed for the traction device based at least in part on a speed of the articulated vehicle and a desired slip rate; and

in response to determining that the traction device speed is less than the target bend speed:

transmitting an isolation signal (122) to the shut valve configured to close the shut valve;

determining a commanded ABS braking pressure; and

transmitting an ABS control signal (116) to the electromechanical brake control valve based on the commanded ABS brake pressure.

2. The braking system of claim 1, wherein the shutoff valve is a normally open valve and the isolation signal energizes and closes the shutoff valve.

3. The brake system of claim 1, further comprising a brake pedal position sensor (123), wherein the brake controller determines the commanded ABS brake pressure based on a position measurement (126) received from the brake pedal position sensor, the position measurement indicative of a displacement of the brake pedal.

4. The braking system of claim 3, further comprising a brake assembly pressure gauge (128) that provides a brake assembly pressure measurement (130) to the brake controller, wherein the brake controller is further configured to:

determining a desired brake pressure based on the position measurement; and

in response to determining that the brake assembly pressure measurement is above the desired brake pressure, providing an enable signal (124) to the shut-off valve configured to open the shut-off valve.

5. The braking system of claim 1, wherein the velocity of the articulated vehicle is determined based at least in part on measurements received from a six degree of freedom (DOF) Inertial Measurement Unit (IMU) (15).

6. The braking system of claim 5, wherein:

the traction means comprise a right side traction means (14-2) arranged on the opposite side of a shaft (17) to the left side traction means (14-1), said shaft extending between the right side traction means and the left side traction means;

the brake controller is further configured to determine a right-side draft gear target bend speed and a left-side draft gear target bend speed; and

determining that the tractor speed is less than the target bend speed includes comparing one of a left tractor speed (26-2) and a right tractor speed (26-1) to a respective one of a left tractor target bend speed and a right tractor target bend speed of the articulated vehicle.

7. The braking system of claim 5, wherein:

the traction means comprise a right side traction means (14-2) arranged on the opposite side of a shaft (17) to the left side traction means (14-1), said shaft extending between the right side traction means and the left side traction means;

the brake controller is further configured to determine a right-side draft gear target bend speed and a left-side draft gear target bend speed; and

determining that the tractor speed is less than the target bend speed includes comparing both a left tractor speed (26-2) and a right tractor speed (26-1) to respective ones of a left tractor target bend speed and a right tractor target bend speed of the articulated vehicle.

8. The braking system of claim 1, wherein the brake controller is further configured to provide a transmission override signal (19) to a transmission controller (18) when the traction device speed is less than the target bend speed.

9. A braking system for an articulated vehicle, the braking system comprising:

a front brake assembly (102-1, 102-2) configured to apply a front brake assembly pressure (104-1) to reduce a rotational speed of a front traction device (14-1, 14-2) disposed in front of an articulation joint (11) in response to receiving one of a front hydro-mechanical pressure signal (106-1) and a front electro-mechanical pressure signal (108-1);

a rear brake assembly (102-3, 102-4, 102-5, 102-6) configured to apply a rear brake assembly pressure (104-2) to reduce a rotational speed of a rear traction device (14-3, 14-4, 14-5, 14-6) disposed rearward of the articulation joint in response to receiving one of a rear hydro-mechanical pressure signal (106-2) and a rear electro-mechanical pressure signal (108-2);

a front electromechanical brake control valve (114-1) and a rear electromechanical brake control valve (114-2) configured to output the front electromechanical pressure signal and the rear electromechanical pressure signal, respectively, each based at least in part on a respective front and rear anti-lock brake system (ABS) control signal;

a front stop valve (118-1) and a rear stop valve (118-2) configured to allow the respective hydro-mechanical pressure signal to control the front brake assembly pressure and the rear brake assembly pressure when the respective stop valve is open and to prevent the respective hydro-mechanical pressure signal from controlling the front brake assembly pressure and the rear brake assembly pressure when the respective stop valve is closed;

a brake controller (120) configured to:

determining respective target bending speeds for the front and rear traction devices based at least in part on a speed and a desired slip ratio of the articulated vehicle; and

in response to determining that a speed of at least one of the front and rear traction devices is less than a respective target bend speed:

transmitting isolation signals (122-1, 122-2) to the front and rear cut-off valves configured to close the front and rear cut-off valves;

determining a commanded ABS braking pressure; and

transmitting a front ABS control signal (116-1) and a rear ABS control signal (116-2) based on the commanded ABS brake pressure to the front electromechanical brake control valve and the rear electromechanical brake control valve.

10. The braking system of claim 9, wherein the front and rear shutoff valves comprise normally open valves, and respective isolation signals energize and close the shutoff valves.

11. The braking system of claim 9, wherein:

the brake controller is further configured to transmit a front ABS control signal based on the ABS brake pressure and a rear ABS control signal further based on an ABS override signal that causes the rear traction device to rotate freely; and

the speed of the articulated vehicle when transmitting the ABS override signal is also based on a rear traction device speed measurement.

12. The braking system of claim 9, wherein the speed of the articulated vehicle includes a respective bend speed associated with respective front and rear traction devices, and determining that the respective traction device speed is less than the target bend speed includes comparing the respective bend speed associated with respective front and rear traction devices to the target bend speed.

13. A method of braking an articulated vehicle, the method comprising:

depressing a brake pedal mechanically coupled to the hydro-mechanical brake control valve to generate a hydro-mechanical pressure signal;

providing a first brake assembly pressure to a brake assembly, the brake assembly being coupled to a traction device, and the first brake assembly pressure being based on the hydro-mechanical pressure signal and configured to reduce a rotational speed of the traction device;

determining a target bend speed for the traction device based at least in part on a speed of the articulated vehicle and a desired slip rate;

transmitting, by a brake controller to a cut-off valve, an isolation signal configured to close the cut-off valve in response to determining that the traction device speed is less than the target bend speed, wherein the hydro-mechanical pressure signal controls the first brake assembly pressure when the cut-off valve is in an open position and the hydro-mechanical pressure signal is prevented from controlling the first brake assembly pressure when the cut-off valve is in a closed position;

determining a commanded ABS brake pressure based on the depression of the brake pedal;

transmitting an ABS control signal from the brake controller to an electromechanical brake control valve based on the commanded ABS brake pressure; and

providing a second brake assembly pressure to the brake assembly, the second brake assembly pressure based on the commanded ABS brake pressure.

14. The method of claim 13, wherein transmitting the isolation signal to the shut valve comprises energizing the shut valve to close the shut valve.

15. The method of claim 13, further comprising:

determining a desired brake pressure based on the displacement of the brake pedal; and

in response to determining that the second brake assembly pressure is greater than the desired brake pressure, providing an enable signal to the shutoff valve configured to open the shutoff valve.

Technical Field

The present disclosure relates to a brake system, and more particularly to a brake system for an articulated vehicle.

Background

Braking a vehicle in a controlled manner under adverse conditions such as rain, snow or ice typically requires the vehicle operator to apply the brakes accurately. Under these conditions, or in the case of panic parking, the driver will typically apply excessive braking pressure, causing the wheels to lock up and slip or skid on the road surface. Wheel lock conditions may result in loss of directional stability and may cause the vehicle to ride uncontrollably backwards.

In order to continuously strive to improve the operational safety of vehicles, anti-lock brake systems have been developed. While such systems are suitable for controlling the braking of each braked wheel of the vehicle, some systems have been developed for controlling the braking of only a portion of the braked wheels. Typically, anti-lock braking systems are electrohydraulic and include a controller and a sensor for monitoring the speed of the controlled wheel to determine deceleration of the controlled wheel. The anti-lock brake system further comprises one or more hydraulic circuits for applying pressure to the brakes of the controlled wheels. When the brakes of the vehicle are applied and the wheel deceleration of the monitored wheel exceeds a predetermined deceleration threshold, indicating wheel slip and the wheel is approaching a locked condition, the controller is to control the application of hydraulic pressure through a series of valves associated with the brakes to prevent locking of the controlled wheel. Typically, the controller will deactivate and activate the valves to cycle the release pressure and reapply pressure to the brakes to limit wheel slip to a safe level while continuing to generate sufficient braking torque to slow the vehicle down as desired by the driver.

One such anti-lock braking system is described in U.S. patent No. 8,919,891. The' 891 patent discloses a brake pedal sensor linked to a brake pedal. The brake pedal is coupled to a normally closed brake pedal valve. The brake pedal valve includes an inlet in communication with a source of pressurized hydraulic fluid and an outlet in communication with a normally open isolation valve. The isolation valve may be in communication with one or more main control valve systems and may be linked to a controller that maintains the isolation valve in a closed position during normal operating conditions. The isolation valve then moves to the open position if the current supply to the controller is interrupted due to an electrical fault or malfunction of the controller.

While effective for their intended purposes, there remains a need for improved braking systems for articulated vehicles.

Disclosure of Invention

In one aspect, an anti-lock brake system for a vehicle is disclosed. The brake system includes a brake assembly coupled to a traction device, the brake assembly configured to apply a brake assembly pressure to reduce a rotational speed of the traction device. The brake assembly pressure is based on one of a hydro-mechanical pressure signal and an electro-mechanical pressure signal. The hydro-mechanical brake control valve is configured to output a hydro-mechanical pressure signal based on the displacement of the brake pedal. The electromechanical brake control valve is configured to output an electromechanical pressure signal based on an anti-lock brake system (ABS) control signal.

A shutoff valve is configured to allow the hydro-mechanical pressure signal to control the brake assembly pressure when the shutoff valve is open and to prevent the hydro-mechanical pressure signal from controlling the brake assembly pressure when the shutoff valve is closed. The brake controller is configured to: determining a target bending speed (corner speed) for the traction device based at least in part on a speed of the articulated vehicle and a desired slip ratio; and in response to determining that the traction device speed is less than the target bend speed: transmitting an isolation signal configured to close the shut-off valve to the shut-off valve; determining a commanded ABS braking pressure; and transmitting an ABS control signal based on the commanded ABS brake pressure to the electromechanical brake control valve.

Another embodiment is in the form of a second brake system for an articulated vehicle including a front brake assembly configured to apply front brake assembly pressure to a front traction device in response to receiving one of a front hydro-mechanical pressure signal and a front electro-mechanical pressure signal. The second brake system also includes a rear brake assembly configured to apply a rear brake assembly pressure to reduce a rotational speed of the rear traction device in response to receiving one of a rear hydro-mechanical pressure signal and a rear electro-mechanical pressure signal.

The second brake system further includes a front electromechanical brake control valve and a rear electromechanical brake control valve configured to output the front electromechanical pressure signal and the rear electromechanical pressure signal, respectively, each based at least in part on a respective front anti-lock brake system (ABS) control signal and rear anti-lock brake system control signal. The front and rear cutoff valves are configured to allow the respective hydro-mechanical pressure signal to control the respective front and rear brake assembly pressures when the respective cutoff valve is open and to prevent the respective hydro-mechanical pressure signal from controlling the respective brake assembly pressure when the respective cutoff valve is closed.

A brake controller in the second brake system is configured to determine respective target bending speeds for the front and rear traction devices based at least in part on a speed and a desired slip ratio of the articulated vehicle. In response to determining that a speed of at least one of the front and rear traction devices is less than a respective target bend speed: the brake controller transmitting an isolation signal configured to close the front stop valve and the rear stop valve to the front stop valve and the rear stop valve; determining a commanded ABS braking pressure; and transmitting front and rear ABS control signals to the front and rear electromechanical brake control valves based on the commanded ABS brake pressure.

Yet another embodiment is in the form of a method of braking an articulated vehicle. The method includes depressing a brake pedal mechanically coupled to a hydro-mechanical brake control valve to generate a hydro-mechanical pressure signal. Providing a first brake assembly pressure to a brake assembly, the brake assembly coupled to a traction device, and the first brake assembly pressure based on the hydro-mechanical pressure signal and configured to reduce a rotational speed of the traction device. Determining a target bend speed for the traction device based at least in part on a speed of the articulated vehicle and a desired slip rate. In response to determining that the traction device speed is less than the target bend speed, the brake controller transmits an isolation signal to a shutoff valve configured to close the shutoff valve. The hydro-mechanical pressure signal controls the first brake assembly pressure when the shutoff valve is in an open position, and prevents the hydro-mechanical pressure signal from controlling the first brake assembly pressure when the shutoff valve is in a closed position. A commanded ABS brake pressure is determined based on the depression of the brake pedal. The brake controller transmits an ABS control signal based on the commanded ABS brake pressure to the electromechanical brake control valve. Providing a second brake assembly pressure to the brake assembly, the second brake assembly pressure based on the commanded ABS brake pressure.

These and other aspects and features of the present disclosure will be more readily understood when read in conjunction with the appended drawings.

Drawings

Fig. 1 depicts a first braking system for an articulated vehicle according to an embodiment of the disclosure.

Fig. 2 depicts a second braking system for an articulated vehicle according to an embodiment of the disclosure.

FIG. 3 depicts a method of braking an articulated vehicle according to an embodiment of the disclosure.

Detailed Description

Turning first to fig. 1, fig. 1 depicts a first braking system 100 for braking an articulated vehicle 10. The articulated vehicle 10 includes a front cab 12 and a rear body 13 (depicted in dashed outline in fig. 1 and 2) separated by an articulation joint 11. Front cab 12 may include an operator compartment and support an engine. The rear body 13 may support a dump body, trailer, or other similar structure. The front cab 12 and the rear body 13 can rotate relative to each other at the articulation joint 11, which rotates about a vertical axis 25.

The articulated vehicle 10 may include a traction device 14 that acts as a ground engaging member for the articulated vehicle 10. For example, traction devices 14 may include a left side traction device 14-1 and a right side traction device 14-2. Traction device 14 may be disposed on opposite sides of an axle 17 extending between left and right traction devices 14-1 and 14-2. The shaft 17 may receive driving force from an engine (not shown) through a portion of the transmission 23 (e.g., a differential gear). In some embodiments, the transmission 23 includes a differential lock for each axle configured to operate between a differential enabled state and a differential locked state in response to receiving a differential control signal.

Brake assembly 102 may be coupled to traction device 14. Brake assembly 102 is configured to receive brake assembly pressure 104 and correspondingly reduce a rotational speed of traction device 14, such as by compressing a pad to a rotor. As depicted in fig. 1, the articulated vehicle 10 includes two front brake assemblies 102. Brake assembly 102-1 is coupled to left traction device 14-1 and brake assembly 102-2 is coupled to right traction device 14-2. In some embodiments, brake assembly pressure 104 may be equally applied to each of the brake assemblies 102-1 and 102-2 on the left and right sides of the articulated vehicle 10. It is contemplated that separate left and right brake assembly pressures may be applied to respective brake assemblies 102.

Although not depicted in fig. 1, it is contemplated that rear body 13 also includes a rear traction device coupled to the brake assembly that supports rear body 13. In one embodiment, the rear body 13 is supported by two left side traction members and two right side traction members. The brake assemblies coupled to the rear traction members may be operated by the same brake assembly pressure 104 that operates the brake assemblies 102-1 and 102-2 of the front traction device 14, or in some embodiments, a separate rear brake assembly pressure may operate the brake assemblies associated with the traction members that support the rear body 13.

The brake assembly 102 may receive an associated brake assembly pressure 104 from the source of pressurized hydraulic fluid 22. As seen in fig. 1, a source of pressurized hydraulic fluid 22 is provided to the hydromechanical brake control valve 110, the electromechanical brake control valve 114, and the relay 21. The brake pedal 112 is coupled to the hydro-mechanical brake control valve 110. When the brake pedal 112 is displaced, such as by an operator depressing the brake pedal 112, the hydromechanical brake control valve 110 is repositioned (e.g., its spool is repositioned) to generate the hydromechanical pressure signal 106. The hydro-mechanical pressure signal 106 is provided to the shutoff valve 118.

When the shutoff valve 118 is in the open position (as depicted in fig. 1), the hydro-mechanical pressure signal 106 is placed in fluid communication with the resolver 20. When the shutoff valve 118 is in the closed position, the hydro-mechanical pressure signal 106 is blocked from fluid communication with the resolver 20. In its closed position, the shut-off valve 118 aligns the fluid path between the resolver 20 and the drain 28. Thus, the hydro-mechanical pressure signal 106 is allowed to control the brake assembly pressure 104 when the shut-off valve 118 is in the open position, and the hydro-mechanical pressure signal 106 is not allowed to control the brake assembly pressure 104 when the shut-off valve 118 is in the closed position.

The first brake system 100 also includes an electromechanical brake control valve 114 configured to output an electromechanical pressure signal 108 based on an anti-lock brake system (ABS) control signal 116. An electromechanical brake control valve 114 is in fluid communication with the source of pressurized hydraulic fluid 22, the resolver 20, and the drain 28. The spool of the electromechanical brake control valve 114 is repositioned in response to the ABS control signal 116 and provides the electromechanical pressure signal 108 to the resolver 20.

The resolver 20 selects the higher of the two control signal pressures between the cut-off valve 118 and the electromechanical brake control valve 114 and provides the higher control signal pressure to the relay 21. The coils of the relay 21 are repositioned based on the control signal selected by the resolver 20. When the coil of the relay 21 is repositioned, the source of pressurized hydraulic fluid 22 is supplied to the brake assembly pressure 104. Brake assembly pressure 104 is provided to brake assemblies 102-1, 102-2 to reduce the rotational speed of the respective traction devices.

In some embodiments, the shut-off valve 118, the electromechanical brake control valve 114, the resolver 20, and the relay 21 are disposed in a valve housing 32 manufactured to accommodate the various components. The valve housing may be a cast component, a machined component, or may be implemented by plumbing the various components together (e.g., the electromechanical brake control valve 114, the resolver 20, and the relay 21).

The first brake system 100 also includes a brake controller 120 in communication with the shutoff valve 118 and the electromechanical brake control valve 114. Brake controller 120 is configured to determine a target bend speed of traction device 14 based at least in part on a speed of articulated vehicle 10 and a desired slip ratio. As the articulated vehicle 10 maneuvers through a work site, the traction device 14 rotates about the axle 17. To reduce the speed of articulated vehicle 10, brake assembly pressure 104 is applied to brake assembly 102 to reduce the rotational speed of traction device 14.

When traction device 14 is in positive engagement with the surface, the bottom surface of the traction device is in stationary contact with the surface. At times, traction devices may spin (e.g., too much acceleration power is provided to traction device 14 via transmission 23) or coast (e.g., too much braking power is provided to traction device 14 via brake assembly 102). In particular, when braking the articulated vehicle 10, the application of excessive braking power may cause the vehicle to coast, reduce the operator's ability to maneuver the articulated vehicle 10, or increase the stopping distance of the articulated vehicle 10. The rotational speed of traction device 14 may be used as an input to the speed of articulated vehicle 10 when traction device 14 is in positive engagement with the surface.

When braking, a target bend speed of traction device 14 may be determined based on a desired slip rate and a speed of articulated vehicle 10. The speed of the articulated vehicle 10 may be determined in any of a variety of ways and provided to the brake controller 120. For example, the speed of the articulated vehicle may be based on speedometer measurements prior to a braking event, measurements from an Inertial Measurement Unit (IMU), Global Positioning System (GPS), or the like. In some embodiments, the IMU is a six degree of freedom (DOF) IMU configured to determine the speed, pitch, roll, yaw, and heading of the articulated vehicle 10.

In some embodiments, the IMU 15-1 is disposed in the front cab 12, the IMU 15-2 is disposed in the rear body 13, and IMU measurements are provided to the brake controller 120 via the communication paths 27-1, 27-2. The bending speed at each of the draft gear positions may be determined based on IMU measurements. The bending speed takes into account the speed of change based on the steering angle of articulated vehicle 10, and when determining the target bending speed for each associated traction device 14, the bending speed may be used as the vehicle speed. Thus, the tractor speed of each tractor located at a turn of the articulated vehicle 10 may be compared to the corresponding target turn speed associated with each turn of the articulated vehicle 10.

Traction device speed may be determined by speed sensor 16. As depicted in FIG. 1, speed sensor 16-1 determines the speed of traction device 14-1 and provides left traction device speed 26-1 to brake controller 120. Speed sensor 16-2 similarly provides right traction device speed 26-2 to the brake controller. Traction device speed 26 may be the actual linear speed of each traction device hub.

The desired slip rate may be based on a desired amount of slip for traction device 14 on the surface. If the brake assembly pressure 104, as controlled by the hydro-mechanical pressure signal, is too high, the traction device 14 may stop rotating while the articulated vehicle 10 continues to move on the surface. Brake controller 120 may determine that the traction device speed is less than the target bend speed for a given traction device 14.

In response to determining that the traction device speed is less than the target bend speed, the brake controller 120 may transmit an isolation signal 122 to the shutoff valve 118 configured to close the shutoff valve. In some embodiments, the shut valve 118 is a normally open valve, and the isolation signal 122 energizes and closes the shut valve 118. Thus, in the event of a loss of electrical power distributed through the articulated vehicle 10, the articulated vehicle 10 maintains the ability to allow the hydro-mechanical brake control valve 110 to control the brake assembly pressure 104. With the shutoff valve 118 closed, the hydro-mechanical pressure signal 106 is blocked from the resolver 20.

In addition, the brake controller 120 determines a commanded ABS brake pressure. The commanded ABS braking pressure may be determined based on the displacement of the brake pedal 112. In this embodiment, the brake pedal 112 is coupled to a brake pedal position sensor 123 configured to determine a displacement of the brake pedal 112 and provide a position measurement 126 of the brake pedal displacement to the brake controller 120. The brake controller 120 may correlate the position measurement 126 to the ABS commanded brake pressure via a reference table.

The brake controller 120 transmits an ABS control signal 116 based on the commanded ABS brake pressure to the electromechanical brake control valve 114. Accordingly, the electromechanical brake control valve 114 is repositioned to align the source of pressurized hydraulic fluid 22 with the resolver 20. In such an embodiment, the shut-off valve 118 is closed, providing nominal (e.g., atmospheric) pressure to the top portion (as shown in fig. 1) of the resolver 20, and the electromechanical brake control valve 114 is repositioned to provide the electromechanical pressure signal 108 to the bottom portion (as shown in fig. 1). Accordingly, the resolver 20 selects the electromechanical pressure signal 108 to control the operation of the relay 21. The relay 21 is then repositioned to align the source of pressurized hydraulic fluid 22 to supply the brake assembly pressure 104. It is therefore the electromechanical brake control valve 114 that controls the operation of the brake assembly 102.

Although fig. 1 depicts operation of first brake system 100 in association with traction device 14 disposed on front cab 12 of articulated vehicle 10, it should be appreciated that first brake system 100 may be further modified to operate brake assembly 102 associated with traction device 14 disposed on rear body 13 of articulated vehicle 10.

In some embodiments, brake assembly pressure 104 is provided to both the forward cab and rear body brake assemblies 102. In yet another embodiment, a separate set of shutoff valves 118, electromechanical brake control valves 114, resolver 20, and relay 21 may be disposed in the valve housing and configured to provide rear brake assembly pressure to the brake assembly 102 associated with the rear traction device 14.

Control of the brake assembly 102 may be restored to the hydromechanical brake control valve 110. In this embodiment, first brake system 100 may also include a brake assembly pressure gauge 128 that measures the pressure of brake assembly pressure 104. The brake assembly pressure gauge 128 provides a brake assembly pressure measurement 130 to the brake controller 120. The brake controller 120 may also be configured to determine a desired brake pressure based on position measurements from the brake pedal position sensor 123.

In response to determining that the brake assembly pressure measurement 130 is above the desired brake pressure, the brake controller 120 provides an enable signal 124 to the shutoff valve 118 to open the shutoff valve 118. For example, the enable signal 124 may be a de-energizing of the isolation signal 122, which causes the shut-off valve 118 to open. In addition, the brake controller 120 may also decrease the magnitude of the ABS control signal 116 to cause the electromechanical brake control valve 114 to reposition to decrease the electromechanical pressure signal 108. Thus, when the pressure at the resolver 20 received from the hydro-mechanical pressure signal 106 through the open shut-off valve 118 is higher than the reduced electro-mechanical pressure signal 108, the resolver 20 selects the hydro-mechanical pressure signal 106 to control the position of the relay 21 (e.g., the position of the coil of the relay 21).

In some embodiments, articulated vehicle 10 includes right side traction device 14-2 and left side traction device 14-1. A shaft may extend between right side traction device 14-2 and left side traction device 14-1 to provide a driving force. In this embodiment, brake controller 120 may be configured to determine a target bending speed for each of right side traction device 14-2 and left side traction device 14-1. These may be different target bending speeds based on the steering angle of the articulated vehicle 10.

In embodiments having left and right traction devices 14, determining whether the target bend speed is less than the traction device speed may be based on one or both of a comparison between the target bend speed and the traction device speed. In other words, the condition that the draft gear speed is less than the target bend speed may be satisfied by one of the left and right draft gear speeds being less than the respective target bend speed or by requiring both the left and right draft gear speeds to be less than the respective target bend speed.

The selection of one or both of the left and right side draft gear speeds to be allowed to be less than the respective target curve speed may be determined based on the desired articulated vehicle performance. Generally, allowing one of the traction device speeds to be less than the corresponding target bend speed to trigger an ABS braking event (e.g., transmission of an isolation signal and an ABS control signal) allows for more active braking. Instead, requiring both traction device speeds to be less than the corresponding target bend speed to trigger an ABS braking event allows for more accurate steering. This difference may be hard coded into the brake controller 120, may be variable based on brake pedal 112 displacement, and the like.

The articulated vehicle 10 may be operated on a work site having various terrains. For example, the right side draft gear may be positioned on a low friction surface like ice and the left side draft gear may be positioned on a high friction surface like gravel. When stopping the articulated vehicle 10, greater steering control may be provided to the articulated vehicle 10 if both traction devices are below the respective target bending speeds and control the brake assembly pressure 104 via the electromechanical pressure signal 108 before closing the shutoff valve 118. Conversely, if only one of the traction devices is below the respective target bending speed before closing the shut-off valve 118 and the brake assembly pressure 104 is controlled via the electromechanical pressure signal 108, a shorter stopping distance of the articulated vehicle 10 may be achieved.

The articulated vehicle 10 may also be equipped with an engine braking system configured to reduce the rotational speed of the traction devices. An engine braking system (not shown) may generally slow the rotational speed of the traction devices through the transmission 23 by utilizing losses through the driveline to provide a braking force to the traction devices. The brake controller 120 may also be configured to provide a transmission override signal 19 to the transmission controller 18 when the electromechanical brake control valve 114 is controlling the brake assembly pressure 104 (e.g., when the traction device speed is less than the target bend speed during an ABS braking event). The transmission controller 18 may be configured to control the amount of engine braking provided by the transmission. In response to receiving the transmission override signal 19, the transmission controller 18 may remove engine braking provided via the transmission 23 (e.g., disengage the engine from the powertrain) so as not to interfere with the control of the traction device speed by the braking system 100. The transmission controller 18 may also maintain transmission action during an ABS braking event and resume normal control and operation of gear shifting and engine braking after the ABS braking event.

FIG. 2 depicts a second braking system of an articulated machine according to an embodiment of the present disclosure. Specifically, fig. 2 depicts a second brake system 200 similar to the first brake system 100 of fig. 1. Like features of the braking systems 100, 200 are similarly numbered throughout.

In general, the second brake system 200 is similar to the first brake system 100, but provides further details of the operation of the brake assembly 102 disposed in both the front cab 12 and the rear body 13. Accordingly, the articulated vehicle 10 includes a front cab 12 having a traction device 14-1 coupled to the brake assembly 102-1 on the left side and a traction device 14-2 coupled to the brake assembly 102-2 on the right side. Brake assemblies 102-1 and 102-2 are operated by front brake assembly pressure 104-1.

The rear body 13 is separated from the front cab 12 by an articulation joint 11 rotating about a vertical axis 25. The rear body 13 comprises four traction devices, two on the left side and two on the right side, but other arrangements are possible. Here, two left side traction devices 14-3 and 14-5 are coupled to brake assemblies 102-3 and 102-5, respectively, and two right side traction devices 14-4 and 14-6 are coupled to brake assemblies 102-4 and 102-6, respectively. Brake assemblies 102-3, 102-4, 102-5, and 102-6 are operated by rear brake assembly pressure 104-2.

The articulated vehicle 10 may include a front valve housing 32-1 disposed in the front cab 12 that houses the front stop valve 118-1, the front resolver 20-1, the front electromechanical brake control valve 114-1, and the front relay 21-1. The articulated vehicle 10 may also include a rear valve housing 32-2 disposed in the rear body 13 that houses the rear stop valve 118-2, the rear resolver 20-2, the rear electromechanical brake control valve 114-2, and the rear electrical appliance 21-2. The operation of the components in front valve housing 32-1 and rear valve housing 32-2 may be similar to the operation of the components of valve housing 32 discussed more fully in connection with first brake system 100 of fig. 1.

The hydro-mechanical brake control valve 210 is similar to the hydro-mechanical brake control valve 110 of FIG. 1, but is configured to provide a front hydro-mechanical pressure signal 106-1 and a rear hydro-mechanical pressure signal 106-2 to operate the brake assemblies in both the front cab 12 and the rear body 13. The front source of pressurized hydraulic fluid 22-1 provides hydraulic pressure for the front hydro-mechanical pressure signal 106-1 and the rear source of pressurized hydraulic fluid 22-2 provides hydraulic pressure for the rear hydro-mechanical pressure signal 106-2. While the front and rear sources 22-1 and 22-2 of pressurized hydraulic fluid may be at the same operating pressure, it is contemplated that the sources of pressurized hydraulic fluid may be operated at different operating pressures for operation of the front and rear brake assemblies 102.

The brake pedal 112 is mechanically coupled to the hydro-mechanical brake control valve 210, and depression of the brake pedal 112 causes the hydro-mechanical brake control valve 210 to generate the front hydro-mechanical pressure signal 106-1 and the rear hydro-mechanical pressure signal 106-2 based on displacement of the brake pedal 112.

The front hydro-mechanical pressure signal 106-1 is provided to the front stop valve 118-1 and the rear hydro-mechanical pressure signal 106-2 is provided to the rear stop valve 118-2.

The brake controller 120 is configured to receive and/or provide a brake pedal position measurement 126, front and rear brake assembly pressure measurements 130-1 and 130-2, a front cut valve isolation signal 122-1 and enable signal 124-1, a rear cut valve isolation signal 122-2 and enable signal 124-2, and front and rear ABS control signals 116-1 and 116-2. The brake controller 120 may also communicate with the steering controller 30 and the transmission controller 18.

The brake controller 120 determines respective target bending speeds for the front and rear traction devices based at least in part on the speed of the articulated vehicle and the desired slip ratio. As discussed above, the speed of the articulated vehicle may be based on the bend speed at the location of each traction device 14. The brake controller 120 may also determine that the speed of the traction device is less than the corresponding target bend speed of the traction device and responsively initiate an ABS braking event. The ABS braking event may include transmitting an isolation signal to the front and rear cutoff valves 118-1 and 118-2, determining a commanded ABS brake pressure, and transmitting a front ABS control signal 116-1 and a rear ABS control signal 116-2 to the respective front and rear electromechanical brake control valves 114-1 and 114-2.

The isolation signals 122-1, 122-2 cause the respective front and rear check valves 118-1, 118-2 to close. In some embodiments, the front and rear cut-off valves 118-1 and 118-2 are normally open valves, and the respective isolation signals energize and close the cut-off valves.

In some embodiments, the front ABS control signal and the rear ABS control signal may be different during an ABS braking event. In one particular example, the brake controller 120 is configured to maintain electromechanical braking of the front brake assemblies 102-1, 102-2 while intermittently removing the rear brake assembly pressure 104-2 to allow the rear traction devices 14-4 through 14-6 to freely rotate. The rear brake assembly pressure 104-2 may be partially removed by decreasing the rear ABS control signal 116-2 to decrease the rear electro-mechanical pressure signal 108-2.

With the rear brake assembly pressure 104-2 removed, the rear traction devices 14-4 through 14-6 may rotate freely. Each of traction device speed sensors 16-3 through 16-5 may provide updated traction device speed measurements to brake controller 120. Since the rear traction devices 14 are free to rotate, they can be used to update the speed of the articulated vehicle, as determined by the IMUs 15-1, 15-2.

The brake controller may continuously or periodically remove the rear brake assembly pressure 104-2 as needed to maintain accurate articulated vehicle speed measurements. Rear brake assembly pressure 104-2 is selected to be removed in lieu of front brake assembly pressure 104-1, as the front brake assembly is expected to provide most of the stopping force to the articulated vehicle 10. The duration of removal of the removed rear brake assembly pressure 104-2 may be approximately one-half second, although other durations may of course be selected. For example, the duration may be based on an estimated speed of the articulated vehicle, a magnitude of a difference between the vehicle speed and the traction device speed, and the like.

The steering controller 30 may receive a steering angle input 31 that indicates the degree of steering of the articulated vehicle (e.g., rotation of the front cab 12 relative to the rear body 13, position of the steering wheel). Based on the steering angle, the brake controller 120 may receive an input from the steering controller 30 indicating a desired steering angle. To provide more accurate steering, the brake controller 120 may provide signals to the transmission 23 (e.g., a differential open signal to the transmission 23, a differential lock signal to the transmission 23) to open or close an axle differential lock for each axle to control torque distribution to the traction devices.

Similar to the first brake system 100, the brake pedal position sensor 123 determines the displacement of the brake pedal 112 and provides a brake pedal position measurement to the brake controller 120. The desired brake pressure may be determined based on a brake pedal position measurement. In response to determining that one of the front and rear brake assembly pressure measurements 130-1, 130-3 is above the desired brake pressure, the brake controller may be further configured to provide an enable signal 124-1, 124-2 to the front and rear shutoff valves 118-1, 118-2, the enable signal configured to open the respective front and rear shutoff valves 118-1, 118-2.

INDUSTRIAL APPLICABILITY

In general, the teachings of the present disclosure may be applied in many braking systems of articulated machines. For example, the teachings of the present disclosure may be applicable to articulated miners, truck trailers, articulated buses, and the like. In one example, the method 300 of FIG. 3 may be used with a brake system of an articulated machine. For example, the first brake system 100 of FIG. 1 will be used in conjunction with the description of the method 300. It is contemplated that one skilled in the art may also implement method 300 using second brake system 200 of FIG. 2.

Method 300 includes depressing a brake pedal at 302, providing a first brake assembly pressure to a brake assembly at 304, determining a target bending velocity of a traction device at 306, determining whether the traction device is less than the target bending velocity at 308, transmitting an isolation signal at 310, determining a commanded ABS brake pressure at 312, transmitting an ABS control signal at 314, and providing a second brake assembly pressure at 316.

At 302, the brake pedal 112 is mechanically coupled to the hydro-mechanical brake control valve and, when depressed, generates the hydro-mechanical pressure signal 106. The hydro-mechanical pressure signal 106 is generated by repositioning the hydro-mechanical brake control valve 110 to align the source of pressurized hydraulic fluid 22 in fluid communication with the shut-off valve 118.

At 304, a first brake assembly pressure is provided to the brake assembly 102. Brake assembly 102 is coupled to traction device 14, and the first brake assembly pressure is based on a hydro-mechanical pressure signal 106 configured to reduce a rotational speed of traction device 14. A first brake assembly pressure is provided to the resolver 20 from a source of pressurized hydraulic fluid 22 through a hydro-mechanical brake control valve 110 through a normally open shutoff valve 118 to control the repositioning of the relay 21. Upon repositioning of relay 21, source 22 of pressurized hydraulic fluid is placed in fluid communication with brake assembly 102 to apply brake pressure to traction device 14.

At 306, a target bend speed of traction device 14 is determined based at least in part on a speed of articulated vehicle 10 and a desired slip ratio.

At 308, it is determined whether the draft gear speed is less than the target bend speed. If not, a first brake assembly pressure is provided at 304. If the traction device speed is less than the target bend speed, the brake controller transmits an isolation signal to the shutoff valve at 310. The isolation signal is configured to close the shutoff valve 118. The hydro-mechanical pressure signal 106 controls the first brake assembly pressure when the shutoff valve 118 is in the open position. When the shutoff valve 118 is in the closed position, the hydro-mechanical pressure signal is prevented from controlling the first brake assembly pressure. This is accomplished in part by the resolver 20 selecting the higher pressure between the electromechanical pressure signal 108 and the hydro-mechanical pressure signal 106 and operating the shutoff valve 118.

At 312, a commanded ABS brake pressure is determined based on depression of the brake pedal 112. At 314, the brake controller transmits an ABS control signal 116 to the electromechanical brake control valve 114 based on the commanded ABS brake pressure.

At 316, a second brake assembly pressure is provided to the brake assembly 102. The second brake assembly pressure is based on the commanded ABS brake pressure from the electromechanical brake control valve 114.

Method 300 may also include determining a desired brake pressure based on the displacement of brake pedal 112. In response to determining that the second brake assembly pressure (e.g., via pressure measurement 130 during an ABS braking event) is greater than the desired brake pressure, the shutoff valve 118 provides an enable signal configured to open the shutoff valve 118.

In some embodiments, the shutoff valve 118 is a normally open valve, and energizing the shutoff valve 118 positions the valve to a closed position, which isolates the hydro-mechanical pressure signal 106 from the resolver 20.

It is also contemplated that method 300 may further include interacting with a transmission and steering controller, splitting braking operations between a front cab and a rear body, and the like, as discussed more fully herein.

From the foregoing, it can be seen that the present disclosure sets forth a braking system for an articulated vehicle. Further, it provides means for providing brake assembly pressure to the brake assembly by hydro-mechanical and electro-mechanical means.