A rotary valve, hydraulic drive system and drive control method suitable for a digital hydraulic motor

Abstract

The application discloses a rotary valve, a hydraulic driving system and a driving control method suitable for a digital hydraulic motor, and belongs to the field of hydraulic transmission and control. The rotary valve comprises a valve core which is installed in the tail end of a motor spindle; one end of the valve core which faces the motor spindle is used for connecting a driving motor; an oil inlet and an oil return port are arranged on the end cover; a distribution disc and the end cover are provided with first and second distribution ports which are respectively connected to a motor cylinder body; a plurality of oil channels are arranged in the valve core and distributed in the circumferential direction of the valve core; two control ports are arranged on the valve core and correspond to the oil channels; control holes are arranged on the motor spindle and correspond to the control ports of the oil channels; the valve core is rotated to connect different oil channels, so that high-pressure oil flows into a motor plunger cavity through the connected oil channels from different distribution ports, and the motor spindle is driven to rotate. The application can simplify the structure of the digital hydraulic motor and improve the dynamic response performance of the digital hydraulic motor.

Description

Technical Field

[0001] This invention relates to a rotary valve, hydraulic drive system, and drive control method suitable for digital hydraulic motors, belonging to the field of hydraulic transmission and control. Background Technology

[0002] Traditional hydraulic technology is an analog control technology, mainly combining switching control, proportional control and servo control from various automation control algorithms. This system has a complex structure, poor reliability, high price and is prone to failure. It requires specialized automation professionals to master, which is not conducive to large-scale promotion and application.

[0003] The rapid development of digital, computer, and information technologies has caused a sensation worldwide. The emergence of digital hydraulic products perfectly aligns with this trend. Digital hydraulic technology directly digitizes hydraulic actuators, achieving reliable operation by receiving pulse signals from digital controllers and computers. The process involves returning control to the electrical system, while the amplified power from digitization is retained by the hydraulic system. Early on, Fujitsu of Japan developed an electro-hydraulic pulse motor controlled by a stepper motor, also known as a stepper hydraulic motor or hydraulic torque amplifier, which has been widely used in the feed transmission of CNC machine tools. Its main components include a stepper motor, a hydraulic motor, a control valve, a screw-nut pair, and a reduction gear pair. The screw-nut pair primarily provides position feedback, ensuring the hydraulic motor always closely follows the stepper motor's movements.

[0004] Existing digital hydraulic motors are mechanically connected by a hydraulic motor, a digital rotary valve, and a feedback mechanism, resulting in a complex structure and large size. They are also prone to drawbacks such as backlash and misalignment, which reduces the dynamic performance of the digital hydraulic motor. Furthermore, the connection between the digital rotary valve and the hydraulic motor is via an external oil circuit, which is long and has a large cavity, further reducing the response performance. Summary of the Invention

[0005] The purpose of this invention is to provide a rotary valve, hydraulic drive system, and drive control method suitable for digital hydraulic motors. By integrating the rotary valve and hydraulic motor into a single design, the drive structure of the hydraulic motor is simplified, while the response performance of the digital hydraulic motor is improved.

[0006] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution: In a first aspect, the present invention provides a rotary valve suitable for a digital hydraulic motor, comprising a valve core installed in the tail end of a motor spindle, wherein an end cover and a distribution plate are provided on the outer periphery of the tail end of the motor spindle; one end of the valve core facing outward from the motor spindle is used to connect to a drive motor; the end cover is provided with an oil inlet and an oil return port, and the distribution plate and the end cover are provided with a first distribution port and a second distribution port respectively connected to the motor cylinder; The valve core has four oil passages; the four oil passages are respectively arranged along the axial direction of the valve core and are located in the middle of the four quadrants around the valve core axis; the valve core has two control ports corresponding to each oil passage, and both ends of each oil passage are respectively connected to the control port along the radial direction of the valve core. The main shaft is provided with control holes corresponding to each oil passage control port; When the valve core rotates to the point where a control port is connected to its corresponding control hole, then at this time there are only two control ports of the oil passages connected to their corresponding control holes. Of the two oil passages connected to the control port, one oil passage is connected to the first distribution port and the oil inlet through the control port and the control hole, respectively, and the other oil passage is connected to the second distribution port and the oil return port through the control port and the control hole, respectively.

[0007] In application, this invention integrates a rotary valve onto the spindle of a digital hydraulic motor. Two distribution ports are connected to the motor cylinder, and a drive motor drives the valve core. When the drive motor rotates the valve core to the control port corresponding to the two oil passages, high-pressure oil introduced from the inlet flows into the motor cylinder through one of the oil passages and the distribution port, causing the motor spindle to rotate. The direction of rotation of the motor spindle varies depending on which oil passage and distribution port the high-pressure oil flows through, thus enabling the rotary valve to drive the digital hydraulic motor. This significantly simplifies the structure of the digital hydraulic motor, reduces the feedback mechanism transmission chain, and improves the dynamic performance of the digital hydraulic motor.

[0008] Optionally, the oil passages can be designated as the first oil passage, the second oil passage, the fourth oil passage, and the third oil passage in sequence around the circumference of the valve core. Projecting the first oil passage and its connected control port onto the second oil passage, the projection of the control port connected to the first end of the first oil passage coincides with the projection of the control port connected to the first end of the second oil passage. If the third oil passage and its connected control port are projected toward the fourth oil passage, then the projection of the control port connected to the first end of the third oil passage coincides with the projection of the control port connected to the first end of the fourth oil passage. The spindle has 6 control holes, of which control holes AP, BP, and PP are located on the same straight line parallel to the spindle axis, and control holes AT, BT, and TT are located on another straight line parallel to the spindle axis. The control port PP is connected to the oil inlet, and its position in the spindle axis corresponds to the position of the first end of the first oil passage and the first end of the second oil passage in the valve core axis; the control port TT is connected to the oil return port, and its position in the spindle axis corresponds to the position of the first end of the third oil passage and the first end of the fourth oil passage in the valve core axis; the positions of the control ports AP, BP, AT, and BT in the spindle axis correspond to the positions of the second end of the second oil passage, the second end of the first oil passage, the second end of the fourth oil passage, and the second end of the third oil passage in the valve core axis, respectively.

[0009] In the above technical solution, the positions of multiple oil passages and the design of control holes on the spindle are jointly optimized, so that different oil passages connecting the oil inlet / return port can share the same control hole in both forward and reverse rotation scenarios. This reduces the number of control holes on the spindle, further simplifies the overall logic of the hydraulic circuit, and shortens the control oil passages and compresses the pipeline volume, which can further improve the response performance of the digital hydraulic motor.

[0010] Optionally, control ports AP and AT are connected to the second distribution port, and control ports BP and BT are connected to the first distribution port. This ensures that high-pressure oil and return oil circuits are provided when different oil passages are open, enabling the motor spindle to rotate in different directions depending on the direction of the oil circuit.

[0011] Optionally, the valve core is a cylinder with four oil passages evenly distributed around the outer periphery of the valve core axis; The straight lines containing control holes AP, BP, and PP, and the straight lines containing control holes AT, BT, and TT, are all on the same plane as the valve core axis. The design of the cylindrical valve core and the position of the spindle control holes simplifies the machining of the workpiece.

[0012] Furthermore, control holes AP and AT are symmetrically arranged with respect to the spindle axis, as are control holes BP and BT. This facilitates the connection between different control holes and the same flow port, and also improves the machining efficiency of the holes on the spindle and valve core.

[0013] In a second aspect, the present invention also provides a hydraulic drive system, including a hydraulic motor, the rotary valve described in the first aspect, and a drive motor; The hydraulic motor has a blind hole axially opened at the tail end of the main shaft. The valve core of the rotary valve is inserted into the blind hole, and the output shaft of the drive motor drives and connects to the tail end of the valve core. The first and second distribution ports on the distribution plate and the end cover are respectively connected to the cylinder of the hydraulic motor.

[0014] Optionally, the end cap is fixedly connected to the mounting end face of the drive motor at one end.

[0015] Optionally, the drive motor is a servo motor, and the output shaft of the servo motor is rigidly connected to the tail end of the valve core.

[0016] Thirdly, the present invention provides a drive control method for the hydraulic drive system described in the second aspect, comprising: When it is necessary to control the hydraulic motor to work, control commands are transmitted to the drive motor, including rotation frequency and direction; The drive motor receives the control command and rotates counterclockwise or clockwise by a set angle according to the control command, such that: When the valve core rotates clockwise to the point where the first oil passage and the fourth oil passage are connected to the corresponding control hole, the two ends of the first oil passage are connected to the oil inlet and the first distribution port via the control port and the control hole, respectively. The two ends of the fourth oil passage are connected to the second distribution port and the return port via the control port and the control hole, respectively. High-pressure oil enters the piston pump in the hydraulic motor cylinder from the first distribution port, generating a torque that makes the main shaft rotate clockwise. When the valve core rotates counterclockwise to the point where the second and third oil passages are connected to the corresponding control holes, the two ends of the second oil passage are connected to the oil inlet and the second distribution port via the control port and the control hole, respectively. The two ends of the third oil passage are connected to the first distribution port and the return port via the control port and the control hole, respectively. High-pressure oil enters the piston pump in the hydraulic motor cylinder from the second distribution port, generating a torque that causes the main shaft to rotate counterclockwise.

[0017] Furthermore, the drive control method of the hydraulic drive system also includes controlling the valve core to rotate to the initial equilibrium position when it is necessary to control the hydraulic motor to stop running, wherein: Based on the oil passage and control port design scheme introduced in the first aspect, when the valve core is in the equilibrium position, the angle between the center line of each control port and the center line of its corresponding control hole is equal. That is, when it is necessary to control the motor to run, whether it is rotating forward or backward, the set angle required for the valve core to rotate is consistent, which can simplify the control logic to a certain extent.

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: (1) The present invention integrates the rotary valve on the spindle of the digital hydraulic motor, connects the two distribution ports to the motor cylinder, and drives the valve core of the drive motor, thus realizing the simple structure and compact layout of the overall digital hydraulic motor. The cylindrical rotary valve core design also makes the processing of the target workpiece simpler. (2) At the same time, the present invention separates multiple oil passages from each other, so that the control ports and control holes corresponding to the multiple oil passages can be connected more accurately and quickly. The control oil passages are shortened and the pipeline volume is compressed accordingly, thus realizing the high response performance of the digital hydraulic motor. (3) By jointly optimizing the position of multiple oil passages and the design of control holes on the main shaft, the present invention enables different oil passages connecting the oil inlet / return port to share the same control hole in both forward and reverse rotation scenarios, reducing the number of control holes on the main shaft and further simplifying the overall logic of the hydraulic circuit. (4) In this invention, a rigid direct feedback is formed between the valve core and the motor spindle, and the drive motor controls the valve core to rotate forward, reverse and stop rotating in a targeted manner. This control process not only eliminates the drawbacks of large gap and misalignment in the original mechanism feedback connection, but also further improves the dynamic performance of the digital motor. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the digital hydraulic motor structure of the present invention; Figure 2 This is a schematic diagram showing the fit between the rotary valve core and the motor spindle of the present invention; Figure 3 This is a schematic diagram of the structure of the motor spindle of the present invention; Figure 4 This is a schematic diagram of the structure of the rotary valve core of the present invention; Figure 5 for Figure 4 A schematic diagram of the radial cross-sections of the rotary valve core shown. Figure 6 This is a radial cross-sectional view of the rotary valve core of the present invention when it is inserted into the blind hole of the motor spindle at its original equilibrium position. Figure 7 This is a schematic diagram of the flow distribution structure of the rotary valve of the present invention; In the diagram: 1-motor spindle; 2-cylinder body; 3-distributor plate; 4-end cover; 5-valve core; 6-drive motor; 7-first oil passage; 8-second oil passage; 9-third oil passage; 10-fourth oil passage; 11-first distribution port; 12-second distribution port. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0021] Example 1 Combination Figures 1 to 7 This embodiment provides a rotary valve suitable for a digital hydraulic motor, including a valve core 5 installed in the tail end of a motor spindle 1. The tail end of the motor spindle 1 is provided with an end cover 4 and a distribution plate 3. The end of the valve core 5 facing outward from the motor spindle 1 is used to connect to a drive motor 6. The end cover 4 is provided with an oil inlet P and an oil return port T. The distribution plate 3 and the end cover 4 are provided with a first distribution port 11 and a second distribution port 12 respectively connected to the motor cylinder 2. The valve core 5 has four oil passages; the four oil passages are respectively arranged along the axial direction of the valve core 5 and are located in the middle of the four quadrants around the valve core axis; the valve core 5 has two control ports corresponding to each oil passage, and both ends of each oil passage are respectively radially connected to the control port along the valve core 5. The motor spindle 1 is provided with control holes corresponding to each oil passage control port; When the valve core 5 rotates to the point where a control port is connected to its corresponding control hole, then at this time there are only two control ports of the oil passages connected to their corresponding control holes. Of the two oil passages connected to the control port, the two ends of one oil passage are connected to the first distribution port 11 and the oil inlet P via the control port and the control hole, respectively. The two ends of the other oil passage are connected to the second distribution port 12 and the oil return port T via the control port and the control hole, respectively.

[0022] In this embodiment, the rotary valve 5 is integrated and installed on the spindle 1 of the digital hydraulic motor. The two distribution ports are connected to the motor cylinder 2, and the drive motor 6 drives the valve core 5. When the drive motor 6 drives the valve core 5 to rotate to the control hole corresponding to the two oil passages, the high-pressure oil introduced from the oil inlet will flow into the motor cylinder 2 through one of the oil passages and the distribution port, thereby causing the motor spindle 1 to rotate. When the oil passage and distribution port through which the high-pressure oil flows are different, the rotation direction of the motor spindle 1 is different, thus realizing the drive of the digital hydraulic motor through the rotary valve 5.

[0023] The digital hydraulic motor in this embodiment not only simplifies the overall structure, but also optimizes the coordination between multiple oil passages, control holes, and control ports, making the feedback mechanism transmission chain shorter and more compact. The input and output process of hydraulic oil between mechanisms is also more targeted, and the efficiency and dynamic performance of the digital hydraulic motor are greatly improved.

[0024] Example 2 Based on Example 1, this example also has the following design: like Figure 2 As shown, in this embodiment, the valve core 5 is cylindrical, and four oil passages are evenly distributed around the outer periphery of the valve core 5 axis, that is, they are located at the center of the four quadrants of the outer periphery of the valve core axis respectively; the cylindrical valve core 5 and the aforementioned internal oil passage distribution design make the processing of the target workpiece simpler.

[0025] The following description refers to the oil passages as the first oil passage 7, the second oil passage 8, the fourth oil passage 10, and the third oil passage 9, in the order of their arrangement around the valve core 5.

[0026] Combination Figure 4 and Figure 5If the first oil passage 7 and its connected control port are projected toward the second oil passage 8, then the projection of the first end of the first oil passage 7 and the control port connected to that end coincides with the projection of the control port connected to the first end of the second oil passage 8. If the third oil passage 9 and its connected control port are projected toward the fourth oil passage 10, then the projection of the first end of the third oil passage 9 and the control port connected to that end coincides with the projection of the control port connected to the first end of the fourth oil passage 10.

[0027] like Figure 3 As shown, the motor spindle 1 has 6 control holes, of which control holes AP, BP, and PP are located on the same straight line parallel to the axial direction of the motor spindle 1, and control holes AT, BT, and TT are located on another straight line parallel to the axial direction of the motor spindle 1.

[0028] The control port PP is connected to the oil inlet P, and its position in the axial direction of the motor spindle 1 corresponds to the position of the first end of the first oil passage 7 and the first end of the second oil passage 8 in the axial direction of the valve core 5; the control port TT is connected to the oil return port T, and its position in the axial direction of the motor spindle 1 corresponds to the position of the first end of the third oil passage 9 and the first end of the fourth oil passage 10 in the axial direction of the valve core 5; the positions of the control ports AP, BP, AT, and BT in the axial direction of the motor spindle 1 correspond to the positions of the second end of the second oil passage 8, the second end of the first oil passage 7, the second end of the fourth oil passage 10, and the second end of the third oil passage 9 in the axial direction of the valve core 5, respectively.

[0029] Control ports AP and AT are connected to the second distribution port 12, and control ports BP and BT are connected to the first distribution port 11.

[0030] As can be seen from the above, this embodiment has jointly optimized the positions of multiple oil passages and the design of control holes on the motor spindle 1, so that different oil passages connecting the oil inlet P and the oil return T can share the same control hole in both forward and reverse rotation scenarios. This not only reduces the number of control holes on the motor spindle 1, but also further simplifies the overall logic of the hydraulic circuit. Furthermore, the control oil passages are shortened and the pipeline volume is compressed, which can further improve the response performance of the digital hydraulic motor.

[0031] like Figure 6As shown, the straight lines containing control holes AP, BP, and PP, and the straight lines containing control holes AT, BT, and TT, are on the same plane as the centerline of the valve core 5. This facilitates the machining of the spindle and the holes on the valve core, and simplifies the control logic of this embodiment: the valve core rotation angle required for the forward and reverse rotation of the spindle is the same. Control holes AP and AT are symmetrically arranged with respect to the axis of the motor spindle 1, and control holes BP and BT are also symmetrically arranged with respect to the axis of the motor spindle 1. This facilitates the connection between different control holes and the same distribution port, and also improves the machining efficiency of the holes on the motor spindle 1 and the valve core 5.

[0032] Example 3 like Figure 7 As shown, this embodiment also provides a hydraulic drive system, including a hydraulic motor, a drive motor 6, and the rotary valve described in the first and second embodiments; The main shaft 1 of the hydraulic motor has a blind hole axially opened at its tail end. The valve core 5 of the rotary valve is inserted into the blind hole. The output shaft of the drive motor 6 drives and connects to the tail end of the valve core 5. The first distribution port 11 and the second distribution port 12 on the distribution plate 3 and the end cover 4 are respectively connected to the cylinder 2 of the hydraulic motor.

[0033] The end cap 4 faces the drive motor 6 and is fixedly connected to the mounting end face of the drive motor 6; the drive motor 6 is a servo motor, and the output shaft of the servo motor is rigidly connected to the tail end of the valve core 5.

[0034] In application, the servo motor 6 drives the valve core to rotate in a specified direction and at a set angle, so that two oil passages are connected. The high-pressure oil introduced by the working port PP reaches the piston chamber in the motor cylinder through one of the oil passages and one of the oil distribution ports. The other oil passage is used for hydraulic oil to flow back to the oil tank, which generates the torque to drive the main shaft to rotate.

[0035] Example 4 This embodiment describes a drive control method based on the hydraulic drive system described in Embodiment 3, including: (a) When the hydraulic motor is not working, valve core 5 is in its initial equilibrium position; such as Figure 7 As shown, after the valve core 5 is inserted into the motor spindle 1, at the initial equilibrium position, control ports a, b, c, d, a', c', b', and d' are completely closed, so even if high-pressure oil is input, the motor spindle 1 will not rotate. (ii) When it is necessary to stop the hydraulic motor, the valve core 5 is controlled to rotate to the initial equilibrium position, wherein: like Figure 6As shown, based on the oil passage and control hole design schemes introduced in Embodiments 1 and 2, when the valve core 5 is in the initial equilibrium position, the angle between the center line of each control port and the center line of its corresponding control hole is equal. That is, when it is necessary to control the motor to run, whether it rotates forward or backward, the set angle required for the valve core 5 to rotate is consistent, and the control logic is clear and easy to design. (III) When it is necessary to control the hydraulic motor, a control command including rotation frequency and direction information is transmitted to the drive motor 6. The valve core 5 rotates synchronously, high-pressure oil enters the corresponding distribution port, and the motor spindle 1 rotates rapidly. The speed and direction both depend on the frequency and direction of the input signal to the drive motor 6. Specifically: After receiving the control command, the drive motor 6 rotates counterclockwise or clockwise by a set angle according to the control command, such that: When the valve core 5 rotates clockwise to the point where the first oil passage 7 and the fourth oil passage 10 are connected to the corresponding control holes, the two ends of the first oil passage 7 are connected to the oil inlet P and the first distribution port 11 via the control port and the control hole, respectively. The two ends of the fourth oil passage 10 are connected to the second distribution port 12 and the return port T via the control port and the control hole, respectively. High-pressure oil enters the piston pump inside the hydraulic motor cylinder 2 through the first distribution port 11, generating a torque that causes the motor main shaft 1 to rotate clockwise. When the valve core 5 rotates counterclockwise to the point where the second and third oil passages are connected to the corresponding control holes, the two ends of the second oil passage are connected to the oil inlet and the second distribution port via the control port and the control hole, respectively. The two ends of the third oil passage are connected to the first distribution port and the return port via the control port and the control hole, respectively. High-pressure oil enters the piston pump in the hydraulic motor cylinder from the second distribution port, generating a torque that causes the main shaft to rotate counterclockwise.

[0036] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A rotary valve suitable for digital hydraulic motors, characterized in that, Includes a valve core (5) installed in the tail end of the motor spindle (1), and an end cover (4) and a distribution plate (3) are provided on the outer periphery of the tail end of the motor spindle (1); the end of the valve core (5) facing outward from the motor spindle (1) is used to connect to the drive motor (6); the end cover (4) is provided with an oil inlet and an oil return port, and the distribution plate (3) and the end cover (4) are provided with a first distribution port (11) and a second distribution port (12) respectively connected to the motor cylinder (2). The valve core (5) has four oil passages; the four oil passages are respectively arranged along the axial direction of the valve core (5) and are respectively located in the middle of the four quadrants around the axis of the valve core (5); the valve core (5) has two control ports corresponding to each oil passage, and the two ends of each oil passage are respectively radially connected to the control port along the valve core (5); The motor spindle (1) is provided with control holes corresponding to each oil passage control port; When the valve core (5) rotates to the point where there is a control port connected to its corresponding control hole, then there are only two oil passages whose control ports are connected to their corresponding control holes. In the two oil passages whose control ports are connected to their corresponding control holes, one oil passage is connected to the first distribution port (11) and the oil inlet through the control port and the control hole, respectively. The other oil passage is connected to the second distribution port (12) and the oil return port through the control port and the control hole, respectively.

2. The rotary valve for a digital hydraulic motor according to claim 1, characterized in that, The oil passages are sequentially designated as the first oil passage (7), the second oil passage (8), the fourth oil passage (10), and the third oil passage (9) in the order of surrounding the valve core (5). Projecting the first oil passage (7) and its connected control port toward the second oil passage (8), the projection of the control port connected to the first end of the first oil passage (7) coincides with the projection of the control port connected to the first end of the second oil passage (8). Projecting the third oil passage (9) and its connected control port toward the fourth oil passage (10), the projection of the control port connected to the first end of the third oil passage (9) coincides with the projection of the control port connected to the first end of the fourth oil passage (10). The motor spindle (1) has 6 control holes, of which control holes AP, BP and PP are located on the same straight line parallel to the axial direction of the motor spindle (1), and control holes AT, BT and TT are located on another straight line parallel to the axial direction of the motor spindle (1). The control hole PP is connected to the oil inlet, and its position on the motor spindle (1) corresponds to the position of the first oil passage (7) and the first end of the second oil passage (8) on the valve core (5) in the axial direction. The control hole TT is connected to the oil return port, and its position on the motor spindle (1) corresponds to the position of the first end of the third oil passage (9) and the fourth oil passage (10) on the valve core (5) in the axial direction. The positions of the control holes AP, BP, AT, and BT on the motor spindle (1) correspond to the positions of the second end of the second oil passage (8), the second end of the first oil passage (7), the second end of the fourth oil passage (10), and the second end of the third oil passage (9) on the valve core (5) in the axial direction, respectively.

3. The rotary valve for a digital hydraulic motor according to claim 2, characterized in that, Control holes AP and AT are connected to the second distribution port (12), and control holes BP and BT are connected to the first distribution port (11).

4. The rotary valve for a digital hydraulic motor according to claim 2, characterized in that, The valve core (5) is a cylinder, and the four oil passages are evenly distributed around the axis of the valve core (5); The straight lines containing control holes AP, BP, and PP, and the straight lines containing control holes AT, BT, and TT, are on the same plane as the centerline of the valve core (5).

5. The rotary valve for a digital hydraulic motor according to claim 4, characterized in that, Control holes AP and AT are symmetrically arranged with respect to the axis of the motor spindle (1), and control holes BP and BT are symmetrically arranged with respect to the axis of the motor spindle (1).

6. A hydraulic drive system, comprising a hydraulic motor, a drive motor (6), and a rotary valve suitable for a digital hydraulic motor as described in any one of claims 2-5; The main shaft (1) of the hydraulic motor has a blind hole axially opened at the tail end. The valve core (5) of the rotary valve is inserted into the blind hole. The output shaft of the drive motor (6) drives and connects to the tail end of the valve core. The first distribution port (11) and the second distribution port (12) on the distribution plate (3) and the end cover (4) are respectively connected to the cylinder body (2) of the hydraulic motor.

7. The hydraulic drive system according to claim 6, characterized in that, The end cap (4) is fixedly connected to the mounting end face of the drive motor (6) at one end.

8. The hydraulic drive system according to claim 6, characterized in that, The drive motor (6) is a servo motor, and the output shaft of the servo motor is rigidly connected to the tail end of the valve core (5).

9. A drive control method based on the hydraulic drive system according to any one of claims 6-8, comprising: When it is necessary to control the hydraulic motor to work, a control command is transmitted to the drive motor (6), the control command including rotation frequency and direction; The drive motor (6) receives the control command and rotates counterclockwise or clockwise by a set angle according to the control command, such that: When the valve core (5) rotates clockwise to the point where the first oil passage (7) and the fourth oil passage (10) are connected to the corresponding control hole, the two ends of the first oil passage (7) are connected to the oil inlet and the first distribution port (11) through the control port and the control hole, respectively. The two ends of the fourth oil passage (10) are connected to the second distribution port (12) and the return port through the control port and the control hole, respectively. High pressure oil enters the piston pump inside the hydraulic motor cylinder (2) from the first distribution port (11) to generate a torque that makes the motor main shaft (1) rotate clockwise. When the valve core (5) rotates counterclockwise to the point where the second oil passage (8) and the third oil passage (9) are connected to the corresponding control hole, the two ends of the second oil passage (8) are connected to the oil inlet and the second distribution port (12) through the control port and the control hole, respectively. The two ends of the third oil passage (9) are connected to the first distribution port (11) and the return port through the control port and the control hole, respectively. High pressure oil enters the piston pump inside the hydraulic motor cylinder (2) through the second distribution port (12) and generates a torque that causes the motor main shaft (1) to rotate counterclockwise.

10. The drive control method according to claim 9, characterized in that, It also includes controlling the valve core (5) to rotate to the initial equilibrium position when it is necessary to control the hydraulic motor to stop running, wherein: When the valve core (5) is in the equilibrium position, the angle between the center line of each control port and the center line of its corresponding control hole is equal.

Images