Control mechanism for rotary hydraulic device

Abstract

The invention relates to the technical field of hydraulic pressure, in particular to a control mechanism for a rotary hydraulic device, which comprises an oil port A, an oil port B and a speed change valve, the speed change valve comprises a speed change valve core and a speed change channel, and a speed change valve cavity is arranged at the end part of the speed change valve core and is used for controlling the speed change valve core to move between a first speed position and a second speed position; the control valve is communicated with the oil port A and the oil port B and comprises a control valve core, and a load valve cavity is formed in the control valve core; when high-pressure oil enters the oil port, the control valve element is at the initial position, the variable-speed valve element is arranged at the first speed position, and the control valve element is switched to the control position, the high-pressure oil is introduced into the variable-speed valve cavity through the variable-speed channel from the control valve, the variable-speed valve element moves to the second speed position, the high-pressure oil enters the load valve cavity and acts on the control valve element, and when the pressure reaches a set value, the variable-speed valve element moves to the load valve cavity. And the control valve element is pushed back to the initial position, so that the variable-speed valve element moves back to the first speed position. The technical problems that in the prior art, the speed needs to be switched manually, and the speed cannot be adjusted automatically are solved.

Description

Technical Field

[0001] This invention relates to the field of hydraulic technology, and in particular to a control mechanism for a rotary hydraulic device. Background Technology

[0002] Currently, excavators on the market generally have a dual-speed requirement, which allows them to switch between high-speed and low-speed driving modes on flat ground. For example, a control device for a hydraulic motor disclosed in document CN102597499A allows for rapid movement of the work site through high-speed driving, but low-speed, high-torque operation is required when working on slopes, necessitating frequent manual speed switching, which increases the difficulty of operation.

[0003] This invention specifically addresses this problem by designing a control mechanism for a rotary hydraulic device that automatically switches to low-speed mode if the motor load reaches a set value in high-speed mode. Summary of the Invention

[0004] To address the technical problem of manual speed switching being required in existing technologies, which cannot be automatically adjusted, this invention provides a control mechanism for a rotary hydraulic device, thus solving the aforementioned technical problem.

[0005] The technical solution of the present invention is as follows: A control mechanism for a rotary hydraulic device includes: oil port A and oil port B. A speed change valve includes a speed change valve core and a speed change channel. The end of the speed change valve core is provided with a speed change valve chamber for controlling the movement of the speed change valve core between a first speed position and a second speed position. A control valve, connected to oil port A and oil port B, includes a control valve core, the control valve core having a load valve chamber, and the control valve being connected to the speed change valve chamber via the speed change channel; When the control valve core is in the initial position, and high-pressure oil is introduced through oil port A or oil port B, the control valve core is configured to be in the first speed position. When the control valve core switches to the control position, high-pressure oil enters the speed change valve chamber through the speed change channel from the control valve. The speed change valve core moves to the second speed position, and high-pressure oil enters the load valve chamber and acts on the control valve core. When the pressure reaches the set value, it pushes the control valve core back to the initial position, causing the speed change valve core to move back to the first speed position.

[0006] According to one embodiment of the present invention, it further includes: a balance valve, which is connected to the oil port A and the oil port B, for controlling the rotation direction of the rotary hydraulic device.

[0007] According to one embodiment of the present invention, the control valve includes a first control oil passage connected to the oil port A, a second control oil passage connected to the balance valve, and a third control oil passage connected to the oil port B.

[0008] According to one embodiment of the present invention, the balance valve is connected to the control valve. High-pressure oil enters the load valve chamber through the balance valve and acts on the control valve core. When the pressure reaches the set value, it can push the control valve core from the control position back to the initial position.

[0009] According to one embodiment of the present invention, it further includes: a signal oil port, wherein when signal oil is supplied through the signal oil port, the control valve switches from the initial position to the control position under the action of the signal oil.

[0010] According to one embodiment of the present invention, the speed change channel is provided with damping.

[0011] According to one embodiment of the present invention, the transmission valve chamber is either the left chamber or the right chamber of the transmission valve. The left chamber of the transmission valve is connected to a first transmission channel, and the right chamber of the transmission valve is connected to a second transmission channel. The transmission valve is connected to the control valve through the first transmission channel and the second transmission channel.

[0012] According to one embodiment of the present invention, the control valve introduces high-pressure oil into the speed change valve chamber through the first speed change channel and the second speed change channel.

[0013] According to one embodiment of the present invention, a load valve core is slidably disposed in the load valve cavity, a spring seat is disposed at one end of the load valve core, a control spring is disposed on the spring seat, one end of the control spring abuts against the spring seat, the other end abuts against the control valve core, and the spring seat abuts against the plug on the end side of the control valve.

[0014] According to one embodiment of the present invention, the high-pressure oil enters the load valve chamber and acts on the load valve core and the control valve core. When the pressure reaches a set value, it works together with the force of the control spring to overcome the signal oil pressure and push the control valve core back to the initial position.

[0015] According to one embodiment of the present invention, the control valve includes: a first pressure chamber into which signal oil can be introduced; a third pressure chamber and a seventh pressure chamber connected to the speed change channel; a fourth pressure chamber connected to the oil port A; a fifth pressure chamber into which high-pressure oil can be introduced; a sixth pressure chamber connected to the oil port B; and a second pressure chamber and an eighth pressure chamber connected to low-pressure oil in the housing.

[0016] According to one embodiment of the present invention, the fifth pressure chamber is in communication with the load valve chamber.

[0017] According to one embodiment of the present invention, the control valve core is in the initial position, at which time the second pressure chamber and the third pressure chamber are connected, and the seventh pressure chamber and the eighth pressure chamber are connected; the control valve core is in the control position, at which time the third pressure chamber and the fourth pressure chamber are connected, and the sixth pressure chamber and the seventh pressure chamber are connected.

[0018] Based on the above technical solution, the technical effects that the present invention can achieve are as follows: In the control mechanism of the rotary hydraulic device of the present invention, when the control valve core is in the initial position, the speed change valve is configured to the first speed position. When the control valve switches to the control position, when high-pressure oil enters the oil port, the high-pressure oil can enter the speed change valve chamber through the control valve, and the speed change valve core moves to the second speed position. At the same time, the high-pressure oil enters the load valve chamber of the control valve and acts on the control valve core, pushing the control valve core back to the initial position. The speed change valve core returns to the first speed position, realizing automatic speed switching.

[0019] The control mechanism of the rotary hydraulic device of this invention uses high-pressure oil from the oil port to enter the load valve chamber and act on the load valve core and control valve core. This, in conjunction with a control spring, overcomes the signal oil pressure, driving the control valve core to reset. In the second speed mode, speed switching is achieved when the oil port pressure reaches a certain value. By adjusting the spring force of the control spring, the load speed change pressure can be adjusted. Furthermore, the speed change pressure can be adjusted by regulating the diameter of the load valve core, adapting to the speed control requirements under different working conditions.

[0020] The control mechanism of the rotary hydraulic device of the present invention integrates the control oil circuit into the control valve. The control valve core controls the connection between the speed change valve chambers on both sides of the speed change valve core and the housing oil or pressure oil. The integrated structural design simplifies the overall structure and reduces manufacturing costs.

[0021] The control mechanism of the rotary hydraulic device of the present invention is provided with a first damper and a second damper on the first and second speed change channels of the oil circuit. By adjusting the size of the damper, the feedback speed of the speed change valve core can be adjusted to prevent the speed change valve core from jumping left and right with the pressure. This effectively eliminates the speed change valve core vibration caused by pressure pulsation during the speed change process, making the speed change smooth and optimizing the driving experience. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of the control mechanism of a rotary hydraulic device according to an embodiment of the present disclosure; Figure 2 This is a schematic diagram of a control valve according to an embodiment of the present disclosure; Figure 3 This is a schematic diagram of a signal oil port according to an embodiment of the present disclosure; Figure 4 This is a schematic diagram of the intermediate oil passage of a balance valve according to an embodiment of the present disclosure; Figure 5This is a schematic diagram of a speed change channel according to an embodiment of the present disclosure; In the diagram: 1-Housing; 2-Oil port A; 3-Oil port B; 4-Balance valve; 41-Balance valve core; 421-Balance valve left chamber; 422-Balance valve left spring; 431-Balance valve right chamber; 432-Balance valve right spring; 44-First channel; 45-Second channel; 46-Intermediate oil passage; 5-Speed ​​change valve; 51-Speed ​​change valve core; 521-Speed ​​change valve left chamber; 522-Speed ​​change valve left spring; 531-Speed ​​change valve right chamber; 532-Speed ​​change valve right spring; 541-First power chamber; 542-Second power chamber; 543-Third power chamber; 544-Fourth power chamber; 551-First speed change channel; 552-First damping ; 561-Second speed change channel; 562-Second damping; 6-Control valve; 61-Control valve body; 62-Control valve core; 631-First control oil passage; 632-Second control oil passage; 633-Third control oil passage; 641-Load valve chamber; 642-Load valve core; 643-Control spring chamber; 644-Control spring; 645-Spring seat; 646-Plug; 651-First pressure chamber; 652-Second pressure chamber; 653-Third pressure chamber; 654-Fourth pressure chamber; 655-Fifth pressure chamber; 656-Sixth pressure chamber; 657-Seventh pressure chamber; 658-Eighth pressure chamber; 7-Signal oil port. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0026] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0027] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0028] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0029] like Figure 1-5As shown in the figure, this embodiment proposes a control mechanism for a rotary hydraulic device, including a housing 1, which is provided with an oil port A2, an oil port B3, a balance valve 4, a speed change valve 5, a control valve 6, and a signal oil port 7.

[0030] Oil port A2 and oil port B3 are connected to balance valve 4 through oil passages in housing 1. Housing 1 defines the first channel 44 and the second channel 45 between balance valve 4 and speed change valve 5, and also defines the power chambers of speed change valve 5, namely the first power chamber 541, the second power chamber 542, the third power chamber 543, and the fourth power chamber 544.

[0031] The balancing valve 4 includes a balancing valve core 41. The balancing valve core 41 has symmetrically arranged balancing valve chambers at its left and right ends, namely a left balancing valve chamber 421 and a right balancing valve chamber 431. A left balancing valve spring 422 is arranged in the left balancing valve chamber 421, with one end of the left balancing valve spring 422 abutting against the balancing valve core 41. A right balancing valve spring 432 is arranged in the right balancing valve chamber 431, with one end of the left balancing valve spring 422 abutting against the balancing valve core 41.

[0032] When high-pressure oil is not introduced into the balance valve chamber, the balance valve core 41 is in the neutral position. When high-pressure oil is connected to port A2, oil returns through port B3, and the high-pressure oil enters the left chamber 421 of the balance valve. Under the action of the high-pressure oil, the balance valve 4 overcomes the force of the right spring 431 and moves from the neutral position to the right end. The high-pressure oil enters the first channel 44 through the balance valve core 41 and connects to the first power chamber 541 through the periphery of the speed change valve core 51, controlling the rotary hydraulic device to operate in the first rotation direction. Furthermore, when high-pressure oil is connected to port B3, oil returns through port A2, and the high-pressure oil enters the second channel 45 through the balance valve core 41 and connects to the fourth power chamber 544 through the periphery of the speed change valve core 51. The rotary hydraulic device operates in the second rotation direction, which is opposite to the first rotation direction.

[0033] The speed change valve 5 includes a speed change valve core 51. The speed change valve core 51 has symmetrical speed change valve chambers on its left and right ends, namely a left speed change valve chamber 521 and a right speed change valve chamber 531. A left speed change valve spring 522 is disposed in the left speed change valve chamber 521, with one end abutting against the speed change valve core 51. A right speed change valve spring 532 is disposed in the right speed change valve chamber 531, with one end abutting against the end side of the speed change valve core 51.

[0034] When high-pressure oil is not introduced into the transmission valve chamber, the transmission valve core 51 is in the neutral position under the action of the left spring 522 and the right spring 532, which is the first speed position. The first power chamber 541 and the second power chamber 542 are connected, as are the third power chamber 543 and the fourth power chamber 544. At this time, the rotary hydraulic device is in the first speed mode, i.e., low speed and high displacement. When high-pressure oil is introduced into the transmission valve chamber, the transmission valve core 51 moves to the left or right end, which is the second speed position. The first power chamber 541, the second power chamber 542, and the third power chamber 543 are connected, while the fourth power chamber 544 is independent; alternatively, the second power chamber 542, the third power chamber 543, and the fourth power chamber 544 are connected, while the first power chamber 541 is independent. At this time, the rotary hydraulic device is in the second speed mode, i.e., high speed and low displacement. The transmission valve core 51 moves between the first and second speed positions to control the speed of the rotary hydraulic device.

[0035] The left chamber 521 of the speed change valve is connected to the control valve 6 through the first speed change channel 551 and the right chamber 531 of the speed change valve is connected to the control valve 6 through the second speed change channel 561. The first speed change channel 551 is provided with a first damper 552 and the second speed change channel 561 is provided with a second damper 562.

[0036] When signal oil is not supplied through signal oil port 7, the transmission valve core is configured to be in the first speed position. When signal oil is supplied through signal oil port 7, the transmission valve core is in the second speed position.

[0037] The control valve 6 includes a control valve body 61, a control valve core 62 slidably disposed within the control valve body 61, a first control oil passage 631, a second control oil passage 632, and a third control oil passage 633. The first control oil passage 631 is connected to oil port A2, and the third control oil passage 633 is connected to oil port B3.

[0038] The control valve body 61 defines pressure chambers arranged along the control valve core 62, which are, in sequence, a first pressure chamber 651, a second pressure chamber 652, a third pressure chamber 653, a fourth pressure chamber 654, a fifth pressure chamber 655, a sixth pressure chamber 656, a seventh pressure chamber 657, and an eighth pressure chamber 658. The first pressure chamber 651 and the eighth pressure chamber 658 are located at both ends of the control valve core 62. The first pressure chamber 651 is connected to the signal oil port 7. The second pressure chamber 652 is connected to the housing oil, which is always low-pressure oil. The third pressure chamber 653 is connected to the first transmission channel 551 and further connected to the left chamber 521 of the transmission valve through the first transmission channel 551. The fourth pressure chamber 654 is connected to the first control oil passage 631. The fifth pressure chamber 655 is connected to the second control oil passage 632. The sixth pressure chamber 656 is connected to the third control oil passage 633. The seventh pressure chamber 657 is connected to the second transmission channel 561 and further connected to the right chamber 531 of the transmission valve through the second transmission channel 561. The eighth pressure chamber 658 is connected to the housing oil.

[0039] The balance valve 4 is provided with an intermediate oil passage 46, which is connected to the second control oil passage 632 of the control valve 6. When the balance valve 4 is in the neutral position, the intermediate oil passage 46 is closed. When high-pressure oil is introduced into the oil port A2 or oil port B3, the balance valve core 41 moves to the end side, the intermediate oil passage 46 opens, and the high-pressure oil enters the fifth pressure chamber 655 through the intermediate oil passage 46.

[0040] A control valve core 62 is provided inside the control valve body 61. A load valve chamber 641 with one axially open end is provided inside the control valve core 62. A control spring chamber 643 is provided on the open end side of the load valve chamber 641. The inner diameter of the control spring chamber 643 is larger than the inner diameter of the load valve chamber 641. The control spring chamber 643 can be set inside the control valve core 62. The load valve chamber 641 is connected to the fifth pressure chamber 655, and the control spring chamber 643 is connected to the eighth pressure chamber 658. The load valve core 642 is slidably arranged inside the load valve chamber 641. One end of the load valve core 642 has a small diameter portion. The outer diameter of the small diameter portion of the load valve chamber 641 and the load valve core 642 form an annular cylindrical oil groove in the load valve chamber 641, which facilitates the opening of the load valve core 642. A spring seat 645 is provided at the other end of the load valve core 642. A control spring 644 is provided on the spring seat 645. One end of the control spring 644 abuts against the spring seat 645, and the other end abuts against the control valve core 62. The control spring 644 is located in the control spring cavity 643. The spring seat 645 abuts against the plug 646 on the control valve end side. The control valve body 61, the control valve core 62, and the plug 646 define the control spring cavity 643. The control oil circuit is highly integrated into the control valve 6. The control valve core 62 controls the connection between the speed change valve cavities on both sides of the speed change valve core 51 and the housing oil or pressure oil. The integrated structural design simplifies the overall structure and reduces manufacturing costs.

[0041] When signal oil is not flowing through signal port 7, control valve core 62 is in the initial left position, and high-pressure oil does not enter the transmission valve chamber. Transmission valve core 51 is in the neutral position, which is the first speed position. When signal oil is flowing through signal port 7, signal oil enters the first pressure chamber 651. Under the action of the signal oil, control valve core 62 overcomes the force of control spring 644 and moves to the right control position. High-pressure oil enters the right chamber 531 or the left chamber 521 of the transmission valve. The moving end of transmission valve core 51 is the second speed position. Whether high-pressure oil enters through port A2 or port B3, high-pressure oil can be introduced into the transmission chamber of transmission valve 5 to achieve speed change.

[0042] The rotary hydraulic device operates in two states: a first speed state and a second speed state. Generally, the first speed state is a low-speed, high-displacement mode, while the second speed state is a high-speed, low-displacement mode.

[0043] When high-pressure oil enters through port A2 and oil returns through port B3, the working process of the control mechanism of the rotary hydraulic device is as follows: When signal oil is not supplied to signal port 7, control valve core 62 is in the initial position on the left. At this time, the second pressure chamber 652 and the third pressure chamber 653 are connected, the seventh pressure chamber 657 and the eighth pressure chamber 658 are connected, the left chamber 521 and the right chamber 531 of the speed change valve are connected to the low-pressure oil of housing 1, and the speed change valve core 51 is kept in the middle position, which is the first speed position. The first power chamber 541 and the second power chamber 542 of the motor are connected, and the third power chamber 543 and the fourth power chamber 544 are connected. At this time, the rotary hydraulic device is continuously in the first speed state.

[0044] When signal oil is connected to signal oil port 7, signal oil is introduced into the first pressure chamber 651. Under the action of the signal oil, the control valve core 62 overcomes the force of the control spring 644 and moves to the right control position. At this time, the third pressure chamber 653 and the fourth pressure chamber 654 are connected, and the sixth pressure chamber 656 and the seventh pressure chamber 657 are connected. High-pressure oil from port A2 enters the left chamber 521 of the speed change valve through the third pressure chamber 653 and the first speed change channel 551, pushing the speed change valve core 51 to move to the right against the force of the right spring 532 of the speed change valve. The speed change valve core 51 moves to the second speed position, and the first power chamber 541, the second power chamber 542, and the third power chamber 543 of the motor are connected, while the fourth power chamber 544 is independent. At this time, the rotary hydraulic device switches to the second speed state. Simultaneously, high-pressure oil acts on the balance valve core 41, overcoming the force of the right balance valve spring 432, and moves it to the right. The intermediate oil passage 46 opens, and high-pressure oil enters the fifth pressure chamber 655 through the intermediate oil passage 46. The fifth pressure chamber 655 is connected to the load valve chamber 641. In the load valve chamber 641, high-pressure oil acts on the load valve core 642 and the control valve core 62. As the load increases, when the high-pressure oil pressure reaches the set value, the high-pressure oil pressure and the force of the control spring 644 together overcome the signal oil pressure, pushing the control valve core 62 back to the initial position on the left. At this time, the second pressure chamber 652 and the third pressure chamber 653 are connected, and the seventh pressure chamber 657 and the eighth pressure chamber 658 are connected. The left chamber 521 and the right chamber 531 of the speed change valve are connected to the low-pressure oil in the housing. The speed change valve core 51 returns to the middle position under the action of the right spring of the speed change valve, which is the first speed position. The rotary hydraulic device automatically switches to the first speed state to realize the load adaptive speed regulation.

[0045] When high-pressure oil enters through port B3, the operation of balance valve 4, speed change valve 5, and control valve 6 is basically the same as when high-pressure oil enters through port A2, and will not be described in detail here.

[0046] The control mechanism of the aforementioned rotary hydraulic device switches the position of the control valve by switching the signal oil on and off, thereby enabling manual switching of the speed mode. In the high-speed, low-displacement mode, the high-pressure oil introduced by the load of the rotary hydraulic device enters the load valve chamber 641 of the control valve 6. When the oil pressure exceeds the set value, it will automatically switch to the low-speed, high-displacement mode. This avoids the need for operators to frequently operate the switching mechanism according to changes in working conditions, significantly reducing the workload of operators, adapting to complex and ever-changing construction scenarios, and having a simple structure and low manufacturing cost.

[0047] The high-pressure oil pressure setting value mentioned in this embodiment is determined by the difference between the force of the signal oil and the force of the control spring 644. The elastic force value can be adjusted by adjusting the control spring 644, thereby setting the load shifting pressure. In addition, the shifting oil pressure threshold can be adjusted by replacing the load valve core 642 with one of different diameters to adapt to different operating conditions.

[0048] The first damper 552 and the second damper 562 on the first transmission channel 551 and the second transmission channel 561 can control the feedback movement speed of the transmission valve core 51 by adjusting the size of the damping orifice. This effectively prevents the valve core from jumping left and right due to oil pressure fluctuations, effectively eliminates the vibration of the transmission valve core caused by pressure pulsation during transmission, makes transmission smooth, improves the working stability of the valve group, and optimizes the driving operation experience.

[0049] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A control mechanism for a rotary hydraulic device, comprising: Oil port A, oil port B, A speed change valve includes a speed change valve core and a speed change channel. The end of the speed change valve core is provided with a speed change valve chamber for controlling the movement of the speed change valve core between a first speed position and a second speed position. A control valve, connected to oil port A and oil port B, includes a control valve core, the control valve core having a load valve chamber, and the control valve being connected to the speed change valve chamber via the speed change channel; The feature is that when high-pressure oil is introduced into the oil port A or the oil port B, and the control valve core is in the initial position, the speed change valve core is configured to be in the first speed position. When the control valve core is switched to the control position, the high-pressure oil enters the speed change valve chamber through the speed change channel from the control valve. The speed change valve core moves to the second speed position, and the high-pressure oil enters the load valve chamber and acts on the control valve core. When the pressure reaches the set value, it pushes the control valve core back to the initial position, causing the speed change valve core to move back to the first speed position.

2. The control mechanism for a rotary hydraulic device according to claim 1, characterized in that, Also includes: A balance valve, connected to oil port A and oil port B, is used to control the rotation direction of the rotary hydraulic device.

3. The control mechanism for a rotary hydraulic device according to claim 2, characterized in that, The control valve includes a first control oil passage connected to the oil port A, a second control oil passage connected to the balance valve, and a third control oil passage connected to the oil port B.

4. A control mechanism for a rotary hydraulic device according to claim 2, characterized in that, The balance valve is connected to the control valve. High-pressure oil enters the load valve chamber through the balance valve and acts on the control valve core. When the pressure reaches the set value, it can push the control valve core from the control position back to the initial position.

5. A control mechanism for a rotary hydraulic device according to claim 1, characterized in that, Also includes: Signal oil port: When signal oil is supplied through the signal oil port, the control valve switches from the initial position to the control position under the action of the signal oil.

6. A control mechanism for a rotary hydraulic device according to claim 1, characterized in that, The speed change channel is equipped with damping.

7. A control mechanism for a rotary hydraulic device according to claim 1, characterized in that, The transmission valve chamber is either the left chamber or the right chamber of the transmission valve. The left chamber of the transmission valve is connected to the first transmission channel, and the right chamber of the transmission valve is connected to the second transmission channel. The transmission valve is connected to the control valve through the first transmission channel and the second transmission channel.

8. A control mechanism for a rotary hydraulic device according to claim 7, characterized in that, The control valve introduces high-pressure oil into the speed change valve chamber through the first speed change channel and the second speed change channel.

9. A control mechanism for a rotary hydraulic device according to claim 1, characterized in that, A load valve core is slidably disposed within the load valve cavity. A spring seat is disposed at one end of the load valve core, and a control spring is disposed on the spring seat. One end of the control spring abuts against the spring seat, and the other end abuts against the control valve core. The spring seat abuts against the plug on the end side of the control valve.

10. A control mechanism for a rotary hydraulic device according to claim 9, characterized in that, The high-pressure oil enters the load valve chamber and acts on the load valve core and the control valve core. When the pressure reaches the set value, it works together with the force of the control spring to overcome the signal oil pressure and push the control valve core back to the initial position.

11. A control mechanism for a rotary hydraulic device according to claim 1, characterized in that, The control valve includes: a first pressure chamber into which signal oil can be introduced; a third pressure chamber and a seventh pressure chamber connected to the speed change channel; a fourth pressure chamber connected to oil port A; a fifth pressure chamber into which high-pressure oil can be introduced; a sixth pressure chamber connected to oil port B; and a second pressure chamber and an eighth pressure chamber connected to low-pressure oil in the housing.

12. A control mechanism for a rotary hydraulic device according to claim 11, characterized in that, The fifth pressure chamber is connected to the load valve chamber.

13. A control mechanism for a rotary hydraulic device according to claim 11, characterized in that, When the control valve core is in the initial position, the second pressure chamber and the third pressure chamber are connected, and the seventh pressure chamber and the eighth pressure chamber are connected; when the control valve core is in the control position, the third pressure chamber and the fourth pressure chamber are connected, and the sixth pressure chamber and the seventh pressure chamber are connected.

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