阅读说明：本技术 一种非差动随动型油缸 (Non-differential follow-up oil cylinder ) 是由 刘凡 夏国锋 文世红 王民 孙行 于 2021-07-14 设计创作，主要内容包括：本发明公开了一种非差动随动型油缸,其包括油缸、举升油口和回拉油口,所述油缸包括油缸大腔和油缸小腔,举升油口与油缸之间串联设置有浮动阀和单向阀,回拉油口与油缸之间串联设置有单向节流阀,油缸大腔通过有第一油路同时连通浮动阀和单向阀,浮动阀为二位二通阀,二位二通阀的截止位连接有液控单向阀,液控单向阀通过第四控制油路连通所述回拉油口,二位二通阀的截止位通过第三控制油路同时连通单向阀和油缸,二位二通阀的导通位分别通过第一控制油路连通所述有第一油路和第二控制油路连通所述举升油口。本发明能满足驾驶室的正常翻转与随动功能,其推力大、便于实现产品的轻量化和小型化,节省制造成本,提高竞争力。(The invention discloses a non-differential motion follow-up oil cylinder which comprises an oil cylinder, a lifting oil port and a pull-back oil port, wherein the oil cylinder comprises an oil cylinder large cavity and an oil cylinder small cavity, a floating valve and a one-way valve are arranged between the lifting oil port and the oil cylinder in series, a one-way throttle valve is arranged between the pull-back oil port and the oil cylinder in series, the oil cylinder large cavity is simultaneously communicated with the floating valve and the one-way valve through a first oil path, the floating valve is a two-position two-way valve, the stop position of the two-position two-way valve is connected with a hydraulic control one-way valve, the hydraulic control one-way valve is communicated with the pull-back oil port through a fourth control oil path, the stop position of the two-position two-way valve is simultaneously communicated with the one-way valve and the oil cylinder through a third control oil path, and the conducting positions of the two-position two-way valve are respectively communicated with the first oil path and the second control oil path to be communicated with the lifting oil port through the first control oil path. The invention can meet the normal overturning and following functions of the cab, has large thrust, is convenient to realize the light weight and miniaturization of products, saves the manufacturing cost and improves the competitiveness.)

1. The utility model provides a non-differential follow-up type hydro-cylinder, includes hydro-cylinder (1), lifts hydraulic fluid port (7) and draws hydraulic fluid port (15) back, hydro-cylinder (1) is including hydro-cylinder big chamber (14) and hydro-cylinder loculus (11), its characterized in that: a floating valve (3) and a one-way valve (2) are arranged between the lifting oil port (7) and the oil cylinder (1) in series, a one-way throttle valve (4) is arranged between the oil return port (15) and the oil cylinder (1) in series, the large oil cylinder cavity (14) is communicated with the floating valve (3) and the one-way valve (2) through a first oil path (10), the floating valve (3) is a two-position two-way valve, the stop position of the two-position two-way valve is connected with a hydraulic control one-way valve (31), the hydraulic control one-way valve (31) is communicated with the oil return port (15) through a fourth control oil path (51), the stop position of the two-position two-way valve is communicated with the one-way valve (2) and the oil cylinder (1) through a third control oil path (61), and the conduction position of the two-position two-way valve is communicated with the first oil path (10) and the second control oil path (71) through a first control oil path (101) respectively to be communicated with the oil lifting port (7).

2. The non-differential follower cylinder as defined in claim 1, wherein: the check valve (2) allows oil in the small oil cylinder cavity (11) to enter the large oil cylinder cavity (14) through the auxiliary oil pipe (6) and is not communicated in the reverse direction.

3. The non-differential follower cylinder as defined in claim 1, wherein: when the hydraulic control one-way valve (31) is conducted, allowing oil liquid in the oil cylinder large cavity (14) to enter the lifting oil port (7) through the first oil path (10); when the hydraulic control one-way valve (31) is cut off, oil in the lifting oil port (7) is allowed to enter the large oil cylinder cavity (14) through the first oil path (10).

4. The non-differential follower cylinder as defined in claim 2, wherein: the oil cylinder (1) comprises a follow-up area and a non-follow-up area, the interface of the follow-up area and the non-follow-up area is the joint of the auxiliary oil pipe (6) and the oil cylinder (1), and the follow-up area comprises the area between the joint of the auxiliary oil pipe (6) and the oil cylinder (1) and the bottom of the oil cylinder large cavity (14).

5. The non-differential follower cylinder as defined in claim 1, wherein: the lifting working condition of the cab: when high-pressure oil is input from the lifting oil port (7), the floating valve (3) is located at a conducting position by the second control oil way (71), the oil enters the large oil cylinder cavity (14) through the main oil way (10), the oil cylinder piston (12) is pushed to move towards the small oil cylinder cavity (11), the piston rod (13) is further pushed to extend out, the hydraulic oil in the small oil cylinder cavity (11) returns to a system oil tank through the main oil pipe (5) through the one-way throttle valve (4) and the pull-back oil port (15), and a cab is lifted.

6. The non-differential follower cylinder as defined in claim 1, wherein: the descending condition of the cab: when high-pressure oil is input from the pull-back oil port (15), the oil enters the small oil cylinder cavity (11) through the main oil pipe (5), the oil cylinder piston (12) is pushed to move towards the large oil cylinder cavity (14), the piston rod (13) is further pushed to retract, the pressure of the third control oil way (61) is equal to that of the first control oil way (101), the floating valve (3) is located at a stop position, when the fourth control oil way (51) reaches a specific pressure, the hydraulic control one-way valve (31) is opened, the hydraulic oil in the large oil cylinder cavity (14) returns to a system oil tank from the lifting oil port (7) through the main oil way (10) and the hydraulic control one-way valve (31), and the cab descends.

7. The non-differential follower cylinder as defined in claim 1, wherein: the following working condition under the oil cylinder is as follows: when the oil cylinder piston (12) is in the follow-up area and the vehicle cab floats downwards relative to the vehicle frame, the piston rod (13) is subjected to downward thrust, the oil cylinder piston (12) presses hydraulic oil in the oil cylinder large cavity (14) downwards to generate pressure, the pressure acts on the floating valve (3) through the first control oil path (101), the floating valve (3) is in a conduction position, and the hydraulic oil in the oil cylinder large cavity (14) returns to the system oil tank from the lifting oil port (7) through the floating valve (3).

8. The non-differential follower cylinder as defined in claim 1, wherein: follow-up working conditions on the oil cylinder are as follows: when the oil cylinder piston (12) is in the follow-up area and the cab of the vehicle floats upwards relative to the frame, the piston rod (13) is subjected to outward pulling force, the floating valve (3) and the hydraulic control one-way valve (31) are both positioned at the stop position, the oil cylinder piston (12) upwards presses hydraulic oil in the small oil cylinder cavity (11), and the hydraulic oil enters the large oil cylinder cavity (14) from the main oil way (10) through the one-way valve (2) through the auxiliary oil pipe (6).

9. The non-differential follower cylinder as defined in claim 1, wherein: the oil cylinder is prevented from sliding down: when oil is supplied from the lifting oil port (7), oil is returned from the pull-back oil port (15) and the oil cylinder piston (12) is in a non-follow-up area, after the oil supply is stopped, the dead weight of the cab acts on the piston rod (13) to push the oil cylinder piston (12) to press the oil cylinder large cavity (14), the floating valve (3) and the hydraulic control one-way valve (31) are both in a stop position, and hydraulic oil in the oil cylinder large cavity (14) cannot be discharged.

10. The non-differential follower cylinder as defined in claim 1, wherein: the oil cylinder is prevented from sliding down: when the oil supply of the oil return port (15) and the oil return of the lifting oil port (7) are performed and the oil cylinder piston (12) is in a non-follow-up area, after the oil supply is stopped, the dead weight of the cab acts on the piston rod (13) to push the oil cylinder piston (12) to press the oil cylinder large cavity (14), the floating valve (3) and the hydraulic control one-way valve (31) are both in a stop position, and hydraulic oil in the oil cylinder large cavity (14) cannot be discharged.

Technical Field

The invention discloses a non-differential follow-up oil cylinder, belongs to the technical field of automobile hydraulic pressure, and particularly discloses a non-differential follow-up oil cylinder of a hydraulic turnover device of a cab of a commercial vehicle.

Background

The overturning of the cab of the driver commercial vehicle is realized through an oil pump and an oil cylinder. The oil cylinder is arranged between the chassis of the vehicle and the cab, the oil pump provides hydraulic power to drive the oil cylinder to stretch and retract so as to lift and pull back the cab, and the cab is required not to fall back freely when being overturned. When the vehicle is in a running state, the cab floats in a limited degree relative to the chassis of the vehicle, and the oil cylinder piston rod assembly is required to move up and down along with the cab within the moving range of the cab, namely, the follow-up function is realized.

At present, a differential servo oil cylinder is mainly adopted for overturning a cab of a commercial vehicle, when large thrust is realized, the cylinder diameter and the rod diameter can only be increased, and the oil cylinder has large volume, heavy mass and high manufacturing cost.

The specification of the chinese utility model patent CN203864823U discloses a cab hydraulic pressure turnover device with dual functions, which comprises a hydraulic oil cylinder assembly and an oil pump assembly, wherein the cylinder body of the hydraulic oil cylinder is provided with a support upper oil circuit, a main oil circuit and a follow-up oil circuit, the support upper oil circuit is provided with a slide valve and a damping valve, the follow-up oil circuit is provided with a damping valve and a hydraulic control double check valve which are connected with the support upper oil circuit, and the support upper oil circuit is connected with the oil pump assembly through a connecting oil pipe; the main oil way can control a hydraulic control double one-way valve on the follow-up oil way through the control oil way, the main oil way is provided with an elastic damping valve, and the main oil way is connected with the oil pump assembly through a connecting pipe. The utility model discloses a flexible shock attenuation efficiency and the during operation system operating pressure that lifts when having the driving are little, the big non-differential function of lift, then have low in manufacturing cost's advantage because of its simple structure in addition, then have long service life's characteristics because of its system pressure is little, but, above-mentioned technical scheme has following defect: when the hydraulic servo-actuated is used, pressure oil in the rod cavity enters an upper oil way of the support through the hydraulic control double-check valve and then flows back to the oil tank through the damping valve, but cannot enter the rodless cavity through the slide valve, and the hydraulic oil way is complex; in a non-follow-up area, the function of preventing the oil cylinder from sliding down can be realized only by simultaneously sealing the valve ports communicated with the upper oil way through the sliding valve and the hydraulic control one-way valve, and the oil cylinder has high failure rate, complex structure and high manufacturing cost; when the driver drives, the shock absorption of the driver's cab is realized by the suspension of the driver's cab, and in practical application, the oil cylinder is not allowed to obstruct the floating of the driver's cab, otherwise, the comfort of the driver's cab is affected.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention provides a non-differential following type oil cylinder which can meet the normal overturning and following functions of a cab, has high thrust, is convenient to realize the light weight and miniaturization of a product, saves the manufacturing cost and improves the competitiveness.

The invention discloses a non-differential servo oil cylinder, which comprises an oil cylinder, a lifting oil port and a back-drawing oil port, wherein the oil cylinder comprises an oil cylinder large cavity and an oil cylinder small cavity, a floating valve and a one-way valve are arranged between the lifting oil port and the oil cylinder in series, a one-way throttle valve is arranged between the return oil port and the oil cylinder in series, the large cavity of the oil cylinder is simultaneously communicated with a floating valve and a one-way valve through a first oil path, the floating valve is a two-position two-way valve, the stop position of the two-position two-way valve is connected with a hydraulic control one-way valve, the hydraulic control one-way valve is communicated with the oil return port through a fourth control oil path, the stop position of the two-position two-way valve is communicated with the one-way valve and the oil cylinder through a third control oil path, and the conducting position of the two-position two-way valve is communicated with the first oil path and the second control oil path through the first control oil path respectively to be communicated with the oil lifting port.

In a preferred embodiment of the invention, the check valve allows oil in the small oil cylinder cavity to enter the large oil cylinder cavity through the auxiliary oil pipe, and the oil is not conducted in the reverse direction.

In a preferred embodiment of the present invention, when the hydraulic control check valve is turned on, the oil in the large cavity of the oil cylinder is allowed to enter the lift oil port through the first oil path; when the hydraulic control one-way valve is closed, oil of the lifting oil port is allowed to enter the large cavity of the oil cylinder through the first oil way.

In a preferred embodiment of the present invention, the oil cylinder includes a following region and a non-following region, an interface between the following region and the non-following region is a junction between the sub oil pipe and the oil cylinder, and the following region includes a region between the junction between the sub oil pipe and the oil cylinder and the bottom of the large cavity of the oil cylinder.

In a preferred embodiment of the invention, the cab lift condition is: when high-pressure oil is input into the lifting oil port, the floating valve is located at a conducting position by the second control oil way, the oil enters the large oil cylinder cavity through the main oil way, the oil cylinder piston is pushed to move towards the small oil cylinder cavity, the piston rod is further pushed to extend out, hydraulic oil in the small oil cylinder cavity returns to a system oil tank through the main oil pipe through the one-way throttle valve and the pull-back oil port, and a cab is lifted.

In a preferred embodiment of the invention, the cab-descent regime is: when high-pressure oil is input from the oil return port, the oil enters the small oil cylinder cavity through the main oil pipe, the oil cylinder piston is pushed to move towards the large oil cylinder cavity, the piston rod is further pushed to retract, the pressure of the third control oil way is equal to that of the first control oil way, the floating valve is at the stop position, when the fourth control oil way reaches a specific pressure, the hydraulic control one-way valve is opened, the hydraulic oil in the large oil cylinder cavity returns to the system oil tank from the oil lifting port through the main oil way and the hydraulic control one-way valve, and the cab descends.

In a preferred embodiment of the invention, when the oil cylinder piston is in the follow-up area and the vehicle cab floats downwards relative to the vehicle frame, the piston rod is subjected to downward thrust, the oil cylinder piston presses down hydraulic oil in the oil cylinder large cavity to generate pressure, the pressure acts on the floating valve through the first control oil path, the floating valve is in a conducting position, and the hydraulic oil in the oil cylinder large cavity returns to the system oil tank from the lifting oil port through the floating valve.

In a preferred embodiment of the invention, when the cylinder piston is in the follow-up area and the vehicle cab floats upwards relative to the vehicle frame, the piston rod is subjected to an outward pulling force, the floating valve and the hydraulic control one-way valve are both in the stop position, the cylinder piston upwards presses hydraulic oil in the small cylinder cavity, and the hydraulic oil enters the large cylinder cavity from the main oil way through the auxiliary oil pipe and the one-way valve.

In a preferred embodiment of the invention, when the oil is supplied from the lifting oil port and returned from the oil return port and the oil cylinder piston is in a non-follow-up area, after the oil supply is stopped, the self weight of the cab acts on the piston rod to push the oil cylinder piston to press the large oil cylinder cavity downwards, the floating valve and the hydraulic control one-way valve are both in a stop position, and hydraulic oil in the large oil cylinder cavity cannot be discharged.

In a preferred embodiment of the invention, when oil is supplied from the oil return port and returned from the oil lifting port and the oil cylinder piston is in a non-follow-up area, after the oil supply is stopped, the dead weight of the cab acts on the piston rod to push the oil cylinder piston to press the large oil cylinder cavity downwards, the floating valve and the hydraulic control one-way valve are both in a stop position, and hydraulic oil in the large oil cylinder cavity cannot be discharged.

The invention has the beneficial effects that: the invention has the advantages of simple structure, high stability, light weight and small volume, and the lifting thrust of the oil cylinder is large and the diameter of the oil cylinder is smaller by the non-differential connection mode, thereby facilitating the light weight and miniaturization of the product; when the piston rod floats upwards, oil in the small oil cylinder cavity directly returns to the large oil cylinder cavity, and the sliding valve of the comparison document CN203864823U stops the oil from returning to the large oil cylinder cavity, so that the oil in the comparison document directly returns to the oil tank, and compared with the comparison document CN203864823U, the oil cylinder has the advantages that the sliding valve is reduced, and the structure is more compact; furthermore, the floating valve and the hydraulic control one-way valve are integrated, so that the control of the hydraulic control one-way valve is simpler; when the automobile is driven, the oil cylinder piston rod assembly moves along with the floating of the cab, so that the floating of the cab is not hindered, and the comfort of the cab is not influenced.

Drawings

FIG. 1 is a first schematic view of a non-differential follower-type cylinder of the present invention;

FIG. 2 is a second schematic view of a non-differential follower-type cylinder of the present invention;

fig. 3 is a schematic diagram of a follow-up area and a non-follow-up area of a non-differential follow-up type cylinder according to the present invention.

Detailed Description

The invention will now be described in further detail, including the preferred embodiments, with reference to the accompanying drawings and by way of illustration of some alternative embodiments of the invention. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, shall fall within the scope of protection of the present invention.

In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for convenience of describing the present application and simplifying the description, but do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as the case may be.

Further, in the present application, relational terms such as "first" and "second", and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The invention discloses a non-differential following oil cylinder which comprises an oil cylinder 1, a one-way valve 2, a floating valve 3 and a one-way throttle valve 4, wherein the floating valve 3 is a two-position two-way valve, the stop position of the two-position two-way valve is connected with a hydraulic control one-way valve 31, a large oil cylinder cavity 14 is connected with a first oil way 10, the first oil way 10 is connected with the one-way valve 2 and the floating valve 3 after being connected out of the large oil cylinder cavity 14, the first oil way 10 is connected with the oil cylinder 1 through an auxiliary oil pipe 6, the floating valve 3 is connected with a lifting oil port 7 through an oil way, and a small oil cylinder cavity 11 is connected with a pull-back oil port 15 through an oil injection pipe 5.

The floating valve 3 is provided with a first control oil path 101, a second control oil path 71, a third control oil path 61 and a fourth control oil path 51, the first control oil path 101 is connected with the first oil path 10 close to the large oil cylinder cavity 14, the second oil path 71 is connected with the lifting oil port 7, the third control oil path 61 is connected with the auxiliary oil pipe 6, the fourth control oil path 51 is connected with the main oil pipe 5, the floating valve 3 is in a left position in a normal state, and the first control oil path 101 and the second control oil path 71 control the floating valve 3 to move left and to be in a right position conduction state.

When the float valve 3 is in the left position, the pilot operated check valve 31 opens the check valve when the main oil pipe 5 reaches a certain pressure, and the fourth pilot oil path 51 is conducted in both directions.

A check valve 2 is arranged between the auxiliary oil pipe 6 and the first oil way 10, the check valve 2 allows oil liquid in the small oil cylinder cavity 11 to enter the large oil cylinder cavity 14 through the auxiliary oil pipe 6, and the oil liquid is not communicated in the reverse direction.

The area where the auxiliary oil pipe 6 is connected is an oil cylinder floating area, and when the oil cylinder piston 12 is located in the area, the oil cylinder loses the function of preventing self-descending and has a follow-up function. When the piston 12 is outside the floating area, the floating valve 3 is in the left position and has the function of preventing sliding downwards.

The following detailed explanation of several working conditions of the present invention is made in conjunction with the drawings and the hydraulic circuit of the present invention:

the lifting working condition of the cab: as shown in fig. 1, when high-pressure oil is input from the lifting oil port 7, the second control oil path 71 makes the floating valve 3 be in the right position (i.e., in the conducting position), the oil enters the large cylinder chamber 14 through the main oil path 10, the cylinder piston 12 is pushed to move toward the small cylinder chamber 11, the piston rod 13 is further pushed to extend, and at this time, the hydraulic oil in the small cylinder chamber 11 returns to the system oil tank through the main oil pipe 5 via the one-way throttle valve 4 and the pull-back oil port 15.

The descending condition of the cab: as shown in fig. 2, when high-pressure oil is input from the oil return port 15, the oil enters the small cylinder cavity 11 through the main oil pipe 5, the cylinder piston 12 is pushed to move towards the large cylinder cavity 14, and the piston rod 13 is pushed to retract, because the pressure of the third control oil path 61 is equal to that of the first control oil path 101, the floating valve 3 is always in the left position under the action of the spring, at this time, the fourth control oil path 51 reaches a specific pressure, the hydraulic control one-way valve 31 is opened, and the hydraulic oil in the large cylinder cavity 14 returns to the system oil tank from the lifting oil port 7 through the main oil path 10 and the hydraulic control one-way valve 31, so that the cab is lowered.

The following working condition under the oil cylinder is as follows: as shown in fig. 1, when the cylinder piston 12 is in the follow-up region and the vehicle cab floats downward relative to the vehicle frame, the piston rod 13 is pushed downward, the cylinder piston 12 pushes down the hydraulic oil in the cylinder large cavity 14 to generate pressure, the pressure acts on the floating valve 3 through the first control oil path 101, when the pressure is enough to overcome the spring force, the floating valve 3 is in a right conducting state, and the hydraulic oil in the cylinder large cavity 14 returns to the system oil tank from the lifting oil port 7 through the floating valve 3, so that a lower follow-up function is realized.

Follow-up working conditions on the oil cylinder are as follows: as shown in fig. 1, when the vehicle cab floats upwards relative to the vehicle frame in the following region (the following region includes a region between the joint of the auxiliary oil pipe 6 and the oil cylinder 1 and the bottom of the large oil cylinder cavity 14, i.e., a shaded region in fig. 3) where the piston 12 of the oil cylinder is located, the piston rod 13 is subjected to an outward pulling force, the piston 12 of the oil cylinder presses the hydraulic oil in the small oil cylinder cavity 11 upwards, and the hydraulic oil enters the large oil cylinder cavity 14 from the main oil passage 10 through the auxiliary oil pipe 6 via the check valve 2, so that an upper following function is realized.

The oil cylinder is prevented from sliding down: as shown in fig. 2, the oil is supplied from the lift oil port 7, the oil is returned from the pull-back oil port 15, the oil cylinder piston 12 is in a non-follow-up area, after the oil supply is stopped, the self weight of the cab acts on the piston rod 13 to push the oil cylinder piston 12 to press the oil cylinder large cavity 14, the first control oil path 101 and the third control oil path 61 on the floating valve 3 have equal pressure (because the first control oil path 101 and the third control oil path 61 are simultaneously connected to the oil cylinder large cavity 14, the pressure of the two is equal), the floating valve 3 is in a left position under the action of a spring, and because no pressure exists in the main oil pipe 5 connected with the control oil path 51, the check valve 31 is always in a closed state, the hydraulic oil in the oil cylinder large cavity 14 cannot be discharged, and the oil cylinder is guaranteed to have no downward sliding phenomenon.

The oil cylinder is prevented from sliding down: as shown in fig. 2, the oil is supplied from the oil return port 15, the oil return port 7 returns oil, the oil cylinder piston 12 is in a non-follow-up area, after the oil supply is stopped, the self weight of the cab acts on the piston rod 13 to push the oil cylinder piston 12 to press the oil cylinder large cavity 14, the pressure of the first control oil path 101 and the third control oil path 61 on the floating valve 3 are equal, the floating valve 3 is in a left position under the action of the spring, because no pressure exists in the main oil pipe 5 connected with the control oil path 51, the hydraulic control one-way valve 31 is always in a closed state, hydraulic oil in the oil cylinder large cavity 14 cannot be discharged, and the oil cylinder is ensured not to slide down.

Note that, in the present embodiment, the left position of the float valve 3 is the stop position of the float valve 3, and the right position of the float valve 3 is the on position of the float valve 3.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, combination, substitution, improvement, etc. made within the spirit and principle of the present invention are included in the scope of the present invention.