Variable control mechanism and control method of hydraulic motor based on inlet pressure compensation

Abstract

The invention discloses a hydraulic motor variable control mechanism based on inlet pressure compensation and a control method. The device comprises a valve body, a shell, a one-way valve body and a variable valve assembly arranged between the shell and the one-way valve body and used for distributing and controlling pressure oil of all cavities. And a one-way valve assembly which is communicated with the oil inlet, the oil outlet and the variable valve assembly and is used for adjusting the flow of system pressure oil introduced into the variable piston so as to drive the inclination angle of the swash plate to change through the axial displacement of the variable piston is arranged in the one-way valve body. Through the design of a valve block oil way, pilot pressure is introduced to serve as compensation when the load pressure of the motor is too low, and it is guaranteed that the running direction of the motor is stable when the motor goes downhill at a high speed.

Description

Technical Field

[0001] This invention relates to the field of hydraulic components technology, to a hydraulic actuator, and more particularly to a variable control mechanism and control method for a hydraulic motor based on inlet pressure compensation. Background Technology

[0002] Hydraulic travel motors are widely used as the travel drive devices for construction machinery. By adjusting the motor's displacement according to actual road conditions, the speed and torque can be switched. The displacement is adjusted by changing the swashplate angle, and the pressure oil required for adjusting the swashplate is the inlet pressure oil, which varies with the load.

[0003] When road conditions are good, such as when a vehicle is on a long downhill section, the vehicle does not require much driving force to descend due to its own weight. At this time, the hydraulic motor inlet pressure is very low, so the force supporting the swashplate becomes very small, causing the swashplate to swing up and down. The instability of the swashplate directly leads to a significant change in the output speed of the hydraulic motor. Since the left and right hydraulic motors of the vehicle are relatively independent, this motor speed change caused by the reduced motor inlet pressure is a state of loss of control. It is possible that both motors will experience this loss of control at the same time, or it may only happen to one motor. When one motor changes speed, the vehicle's forward direction will deviate. At this time, due to good road conditions and high vehicle speed, loss of steering control can cause very serious damage and pose a great safety hazard.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] This invention provides a variable displacement control mechanism and method for a hydraulic motor based on imported pressure compensation to solve the problem of speed change during high-speed downhill driving. To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments. Its sole purpose is to present some concepts in a simple form as a prelude to the detailed description that follows.

[0006] In one embodiment, a variable displacement control mechanism for a hydraulic motor based on inlet pressure compensation includes a valve body, a housing, and a check valve body. A main shaft, a swashplate, and a variable displacement piston are disposed within a accommodating space formed by the valve body, housing, and check valve body. The swashplate is sleeved on the outer wall of the main shaft, and the variable displacement piston is installed within the accommodating space and cooperates with the swashplate. The variable displacement piston acts on the swashplate to adjust the swashplate's swing angle θ. The mechanism further includes: A variable valve assembly for distributing and controlling the pressure oil in each chamber is provided between the housing and the one-way valve body; The one-way valve body is provided with a one-way valve assembly that communicates with the oil inlet, oil outlet and variable valve assembly to regulate the flow rate of the system pressure oil introduced into the variable piston, thereby driving the swashplate tilt angle to change through the axial displacement of the variable piston.

[0007] Based on the above solution, the one-way valve assembly includes: A first check valve assembly is axially arranged in the body of the check valve, which is connected to the oil inlet or the oil outlet. A second check valve assembly connected to the oil outlet or oil inlet; And a third check valve assembly connected to the variable valve assembly for pressure compensation at low loads.

[0008] Based on the above scheme, the variable valve assembly includes a variable valve core and a variable valve core return spring for providing a return force to the variable valve core.

[0009] In addition, the present invention also provides a control method for a variable control mechanism of a hydraulic motor based on inlet pressure compensation, comprising the following steps: Large displacement mode: When the pilot signal pressure is 0, the variable valve core moves to the right under the action of the variable valve core return spring, blocking the oil passages of chamber A and chamber B, the swashplate maintains a tilt angle of 16.7°, and the third check valve assembly is in the closed state.

[0010] Based on the above scheme, in the small displacement mode: when the pilot pressure reaches 3.5MPa, the variable valve core moves to the left to connect the oil circuits of chamber A and chamber B. The high-pressure oil at the inlet or outlet pushes the variable piston, causing the swashplate tilt angle to drop to 7.3°, and the third check valve assembly is in the closed state.

[0011] Based on the above scheme, under extremely low load, if the inlet or outlet pressure is lower than 3.5MPa, the third check valve assembly opens, introducing pilot pressure to the bottom of the variable piston, so that the motor continues to maintain the swashplate tilt angle at 7.3°.

[0012] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects: This invention utilizes a third one-way valve assembly to employ pilot pressure as compensation when the motor load pressure is too low, ensuring the stability of the motor's direction of travel during high-speed downhill driving. It also introduces a pilot signal pressure to the bottom of the variable displacement piston of the hydraulic motor when the inlet pressure is insufficient, ensuring that the swashplate of the hydraulic motor always receives sufficient support and remains stable at high speed. This fundamentally eliminates the possibility of speed reduction when the inlet pressure of the hydraulic motor is insufficient, preventing accidents.

[0013] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0014] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0015] Figure 1 This is a schematic diagram of the structure of a variable control mechanism for a hydraulic motor based on inlet pressure compensation, according to an exemplary embodiment. Figure 2 This is a schematic diagram of a variable control mechanism based on an inlet pressure-compensated hydraulic motor, according to an exemplary embodiment (showing that when encountering flat roads and road conditions with low driving resistance, it is necessary to increase the driving speed, the hydraulic motor is in a small displacement state, and the oil inlet is connected to the first check valve assembly). Figure 3 This is a schematic diagram of a variable control mechanism based on an inlet pressure-compensated hydraulic motor, according to an exemplary embodiment (showing that when encountering flat roads and road conditions with low driving resistance, it is necessary to increase the driving speed, the hydraulic motor is in a small displacement state, and the oil inlet is connected to the second check valve assembly). Figure 4 This is a schematic diagram of the structure of a variable control mechanism based on an imported pressure-compensated hydraulic motor according to an exemplary embodiment (showing the hydraulic motor in a small displacement, high-speed state when encountering downhill and road conditions with very low driving resistance or even passive driving due to the weight of the equipment itself). Detailed Implementation

[0016] The following description and accompanying drawings fully illustrate specific embodiments described herein to enable those skilled in the art to practice them. Some embodiments may include or substitute parts and features of other embodiments. The scope of the embodiments herein encompasses the entire scope of the claims and all available equivalents thereof. Throughout this document, the terms “first,” “second,” etc., are used only to distinguish one element from another without requiring or implying any actual relationship or order between the elements. Indeed, a first element can also be referred to as a second element, and vice versa. Furthermore, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a structure, apparatus, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a structure, apparatus, or device. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the structure, apparatus, or device that includes said element. The various embodiments described herein are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments; similar or identical parts between embodiments can be referred to interchangeably.

[0017] The terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" used in this document to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings. They are used solely for the convenience of describing the document and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description herein, unless otherwise specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two elements; they can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0018] In this document, unless otherwise stated, the term "multiple" means two or more.

[0019] In this article, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0020] In this article, the term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0021] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0022] Figure 1 An embodiment of the present invention is shown, which is a variable control mechanism for a hydraulic motor based on inlet pressure compensation.

[0023] The variable control mechanism of the hydraulic motor based on imported pressure compensation is used to drive the swashplate 4 of the piston pump or piston motor to swing. The variable control mechanism is installed between the valve body 1, the housing 2 and the one-way valve body 3 to form a accommodating space. A main shaft 5, a swashplate 4 and a variable piston 6 are arranged between the valve body 1 and the housing 2. The swashplate 4 is sleeved on the outer wall of the main shaft 5. The variable piston 6 is installed in the accommodating space and cooperates with the swashplate 4. The variable piston 6 acts on the swashplate 4 to adjust the swing angle θ of the swashplate 4.

[0024] In this structure, the variable displacement of the motor can be adjusted by changing the swing angle θ of the swashplate 4. The swashplate 4 is positioned by a hydraulic positioning piston. This positioning method can adjust the swing angle of the variable swashplate 4. As the swing angle θ of the swashplate 4 increases, the displacement and torque also increase, and vice versa. If the swing angle is 0, the displacement is zero. The control pressure port is connected to the load. When the load pressure exceeds the pressure adjusted by the valve, the load pressure oil enters the control pressure port to push its valve core to move. The load pressure oil enters the housing 2, which can make the swashplate 4 swing counterclockwise. As the swing angle θ increases, the reciprocating stroke of the piston rod increases, thus adjusting the variable displacement of the motor. As the volume increases, the torque of the output shaft also increases. When it is balanced with the load, the valve closes.

[0025] This design utilizes the inlet pressure of the hydraulic motor to act on the variable piston at the bottom of the swashplate 4, causing a change in the swashplate angle, thereby changing the hydraulic motor's displacement and ultimately its output speed. The difference lies in that when the hydraulic motor inlet pressure is insufficient, this solution introduces the pilot signal pressure that drives the variable valve core to the bottom of the hydraulic motor's variable piston 6. This ensures that the hydraulic motor swashplate 4 always receives sufficient support, maintaining a stable high-speed operation. This fundamentally eliminates the possibility of speed reduction due to insufficient hydraulic motor inlet pressure, preventing accidents. This embodiment specifically includes: A variable valve assembly 7 for distributing and controlling the pressure oil in each chamber is disposed between the housing 1 and the one-way valve body 3. The variable valve assembly 7 includes a variable valve core 701 and a variable valve core return spring 702 for providing a return force to the variable valve core 701.

[0026] As a specific implementation scheme, the variable control mechanism of the hydraulic motor based on inlet pressure compensation further includes: a first check valve assembly 301 axially disposed within the check valve body 3 and communicating with the oil inlet or outlet; a second check valve assembly 302 communicating with the oil outlet or inlet; and a third check valve assembly 303 communicating with the variable valve assembly 7. Specifically, when the oil pressure in the system meets certain conditions, the check valve opens, allowing the oil to flow in a specific direction; when the pressure conditions are not met, the check valve closes, preventing the oil from flowing in the opposite direction.

[0027] In the above scheme, the first one-way valve assembly 301, the second one-way valve assembly 302 and the third one-way valve assembly 303 can be selected from conventional one-way valve structures. Their specific structures are not innovative points of this invention and will not be described in detail here.

[0028] like Figure 1 As shown, when this variable mechanism is not working (large displacement): When the pilot signal pressure is 0, the variable valve core 701 is on the right side under the action of the variable valve core return spring 702. Chambers A and B are blocked by the variable valve core 701. There is no pressure oil at the variable piston 6. At this time, the swashplate 4 angle is 16.7 degrees, which is a large displacement state. In this state, the motor output speed is low and the output torque is high, which is suitable for road conditions with high driving resistance such as uphill. like Figure 2 and Figure 3 As shown, when encountering flat roads and conditions with low driving resistance, it is necessary to increase the driving speed. At this time, the variable displacement mechanism is activated, and the motor is adjusted to a small displacement state. At this time, the high-speed signal pressure of the motor is 3.5MPa. The pilot oil acts on the right end of the variable valve core 701 through the variable pilot oil port. When the hydraulic thrust at the right end of the variable valve core 701 is greater than the spring force, the variable valve core 701 moves to the left. The A and B chambers in the middle position of the variable valve core 701 are connected. In this case, depending on the direction of motor rotation, sometimes the inlet pressure is higher and sometimes the outlet pressure is higher. Under normal circumstances, it will be higher than 3.5MPa. The third check valve assembly 303 is generally in the closed state. The inlet pressure oil or the outlet pressure oil enters the bottom of the variable piston 6 through the passage in the middle of the variable valve core 701. The variable piston 6 moves upward under the action of hydraulic pressure, pushing the swashplate 4 tilt angle from 16.7 degrees to 7.3 degrees, so that the motor is in a small displacement state. In this state, the motor output speed is high and the output torque is low, which is suitable for road conditions with low driving resistance such as downhill. In the above scheme, the first check valve assembly 301 and the second check valve assembly 302 are respectively connected to the inlet / outlet oil port and the variable valve core passage. In the small displacement mode (pilot pressure ≥ 3.5MPa), the high pressure oil circuit (inlet or outlet) is selectively opened to introduce the system pressure oil into the bottom of the variable piston 6, driving the swashplate 4 to reduce the tilt angle to 7.3°. like Figure 4As shown, when encountering downhill slopes or road conditions with very low driving resistance or even passive movement due to the weight of the equipment itself, the hydraulic motor operates at a small displacement and high speed. At this time, the inlet and outlet pressures are relatively low, sometimes as low as around 0 MPa. At this time, the high-speed signal pressure of the motor is 3.5MPa. The pilot oil acts on the right end of the variable valve core 701 through the variable pilot oil port. When the hydraulic thrust at the right end of the variable valve core 701 is greater than the spring force, the variable valve core 701 moves to the left, and the A and B chambers in the middle position of the variable valve core 701 are connected. In this case, the pressure at the motor inlet or outlet is low. When it is lower than 3.5MPa, the third check valve assembly 303 will open, and the pilot pressure will enter the bottom of the variable piston 6 through the passage in the middle of the variable valve core 701 to make up for the insufficient pressure at the inlet oil port. This ensures that the motor continues to maintain the swashplate 4 tilt angle at 7.3 degrees, so that the motor is stably in a small displacement state. It will not cause the swashplate 4 to lose support and the angle to return to a large angle state due to the decrease in the pressure at the motor inlet and outlet oil ports, resulting in the motor becoming slow and the vehicle's driving direction becoming uncontrollable. In the above scheme, the third one-way valve assembly 3 serves as the core of pressure compensation. Under extremely low load (such as long downhill), when the inlet / outlet oil pressure is <3.5MPa, it automatically opens to replenish the pilot pressure oil to the bottom of the variable piston 6, forcibly maintaining the small angle of the swashplate and avoiding sudden changes in speed due to insufficient support.

[0029] The above solution, through ingenious structural design, retains the mature approach of using system pressure variables when the hydraulic motor is under high load, while also solving the instability problem caused by insufficient swashplate support force when the hydraulic motor is under low load. When the internal oil pressure of the motor variable piston is lower than the pressure required by the motor variable, the pilot oil circuit will compensate for it, and when the internal oil pressure is higher than the pressure required by the motor variable, the pilot oil circuit will close, thereby ensuring the stability of the motor variable and solving the problem of loss of steering control when the vehicle is going downhill.

[0030] An embodiment of the control method of the variable control mechanism of the hydraulic motor based on inlet pressure compensation of the present invention.

[0031] The variable displacement control mechanism based on the imported pressure-compensated hydraulic motor achieves displacement switching by dynamically adjusting the swashplate tilt angle. The control method is as follows: 1. Large displacement mode (high torque / low speed): When the pilot signal pressure is 0, the variable valve core 701 moves to the right under the action of the variable valve core return spring 702, blocking the oil circuit of chamber A / B. The swashplate 4 maintains a tilt angle of 16.7°, which is suitable for high resistance conditions such as uphill. 2. Small displacement mode (low torque / high speed): When the pilot pressure reaches 3.5MPa, the variable valve core 701 moves to the left to connect the A / B chambers. The high pressure oil (>3.5MPa) at the inlet / outlet pushes the variable piston 6, causing the swashplate 4 tilt angle to drop to 7.3°, which is suitable for flat or downhill conditions. 3. Pressure compensation mechanism: Under extreme low load (such as long downhill), if the inlet / outlet pressure is lower than 3.5MPa, the third check valve assembly 303 opens, introducing pilot pressure to the bottom of the variable piston 6.

[0032] This invention uses pilot pressure to compensate for low motor load pressure through the design of the valve block oil circuit, ensuring the stability of the motor's direction of travel when going downhill at high speed.

[0033] This invention is not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this invention is limited only by the appended claims.

Claims

1. A variable displacement control mechanism for a hydraulic motor based on imported pressure compensation, comprising a valve body (1), a housing (2), and a check valve body (3), wherein a main shaft (5), a swashplate (4), and a variable displacement piston (6) are disposed within a accommodating space formed by the valve body (1), the housing (2), and the check valve body (3), the swashplate (4) being sleeved on the outer wall of the main shaft (5), the variable displacement piston (6) being installed within the accommodating space and cooperating with the swashplate (4), the variable displacement piston (6) acting on the swashplate (4) to adjust the swing angle θ of the swashplate (4), characterized in that, Also includes: A variable valve assembly (7) for distributing and controlling the pressure oil in each chamber is provided between the housing (1) and the one-way valve body (3). The one-way valve body (3) is provided with a one-way valve assembly that is connected to the oil inlet, oil outlet and variable valve assembly (7) for regulating the flow of system pressure oil introduced into the variable piston (6), thereby driving the swashplate (4) to change its tilt angle through the axial displacement of the variable piston (6).

2. The variable control mechanism for a hydraulic motor based on imported pressure compensation according to claim 1, characterized in that, The one-way valve assembly includes: A first check valve assembly (301) is axially arranged inside the check valve body (3) and communicates with the oil inlet or the oil outlet. A second check valve assembly (302) connected to the oil outlet or oil inlet; And a third check valve assembly (303) connected to the variable valve assembly (7) for pressure compensation at low loads.

3. The variable control mechanism for a hydraulic motor based on imported pressure compensation according to claim 1 or 2, characterized in that, The variable valve assembly (7) includes a variable valve core (701) and a variable valve core return spring (702) for providing a return force to the variable valve core (701).

4. A control method for a variable displacement control mechanism based on an imported pressure-compensated hydraulic motor, characterized in that, The variable control mechanism based on the hydraulic motor with inlet pressure compensation as described in any one of claims 1-3 includes the following steps: Large displacement mode: When the pilot signal pressure is 0, the variable valve core (701) moves to the right under the action of the variable valve core reset spring (702), blocking the oil passages of chamber A and chamber B. The swashplate (4) maintains an inclination angle of 16.7°, and the third check valve assembly (303) is in the closed state.

5. The control method for the variable control mechanism of the hydraulic motor based on imported pressure compensation according to claim 4, characterized in that, Small displacement mode: When the pilot pressure reaches 3.5MPa, the variable valve core (701) moves to the left to connect the oil circuits of chamber A and chamber B. The high pressure oil at the oil inlet or outlet pushes the variable piston (6), causing the swashplate (4) tilt angle to drop to 7.3°, and the third check valve assembly (303) is in the closed state.

6. The control method for the variable control mechanism of the hydraulic motor based on inlet pressure compensation according to claim 4, characterized in that, Under extremely low load conditions, if the inlet or outlet pressure is below 3.5 MPa, the third check valve assembly (303) opens, introducing pilot pressure to the bottom of the variable piston (6), so that the motor continues to maintain the swashplate (4) tilt angle at 7.3°.

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