A double-acting power unit

Abstract

The utility model discloses a double -acting power unit, including first control oil circuit, second control oil circuit, hydraulic pump and the core's two -way self -control oil return valve, two -way self -control oil return valve is through its inside movable oil return valve core, and the oil circuit is switched automatically in response to the oil supply direction of hydraulic pump, when the motor normal rotation, and the oil oil promotes the oil return valve core to remove, and the oil supply side direct oil return passage is cut off, and the oil return road of another side is conducted, and the drive oil cylinder is stretched out, when the motor reverses, and the oil return valve core reverse action is removed, and the surplus oil liquid of the rodless chamber of oil cylinder is provided with the unobstructed oil return channel to the oil tank in the drive oil cylinder retraction, thereby intelligently solve the system pressure -holding problem of oil volume difference, the utility model discloses realize full -automatic, the oil circuit switching and oil return management of external control signal, has compact structure, energy -conserving, reliable and the advantage of low cost, especially suitable for medical bed, industrial equipment and so on to the occasion of high space and control accuracy requirement.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic control systems, and in particular to a double-acting power unit. Background Technology

[0002] In equipment and actuators, bidirectional power units are often used to control the mechanism. That is, by using the forward and reverse rotation of the motor, the inlet and outlet of the oil circuit are reversed to achieve the required functions, such as extension, lifting and other actions.

[0003] Currently, there are many types of power units on the market, but their basic principles are similar, consisting of a motor (2a), hydraulic pump, relief valve, oil tank, main control valve assembly, and hydraulic lock. (See...) Figure 1 In the power unit, when motor 2a rotates forward, hydraulic pump 3a draws oil from filter 7a, the left check valve closes, hydraulic pump discharges oil, and oil is supplied to the bottom of cylinder 8a, pushing cylinder 8a upward. Conversely, when motor 2a rotates in reverse, the right check valve of hydraulic pump 3a closes and discharges oil, oil is supplied to the top of cylinder 8a, pushing cylinder 8a downward. When motor 2a stops rotating, pressure is maintained by hydraulic lock 4a to prevent cylinder 8a from moving, thus achieving motion control.

[0004] However, in this type of power unit, because the bottom cavity of cylinder 8a is larger than the top cavity, excess oil must be discharged when cylinder 8a descends; otherwise, the entire system will stall and become inoperable. The common practice in existing technology is to add a bypass circuit return valve 9a or to directly discharge oil from the overflow valve 5a. Both solutions have certain drawbacks. Adding a bypass circuit increases the number of solenoid valves, affecting the system's pressure-holding performance and safety; it also reduces integration and increases the required installation space; additional electrical control systems are needed. Secondly, to achieve good pressure-holding performance, the solenoid valves require high pressure-holding capacity, thus increasing design and manufacturing costs. If direct overflow occurs, the overflow valve remains open, converting some of the hydraulic oil's kinetic energy into heat, resulting in significant heat generation and high energy consumption. Thirdly, for low-flow systems, this solution typically uses a high-performance, expensive miniature piston pump, leading to high costs.

[0005] Therefore, a technical solution is needed to overcome the above problems. Utility Model Content

[0006] To overcome some shortcomings in the existing technology, the purpose of this utility model is to provide a dual-action power unit to solve the above-mentioned technical problems.

[0007] To achieve its purpose, the present invention adopts the following technical solution: a double-acting power unit for hydraulic cylinder lifting, comprising: The first control oil circuit connects the oil tank to the bottom of the oil cylinder; The second control oil circuit connects the oil tank to the top of the oil cylinder; A hydraulic pump is connected to a motor and is connected between the first control oil circuit and the second control oil circuit. Driven by the motor, the hydraulic pump is used to draw oil from the oil tank and deliver the liquid oil to the first control oil circuit or the second control oil circuit. A first check valve and a second check valve, wherein the inlet and outlet of the hydraulic pump are respectively connected to the oil tank via the first check valve and the second check valve; and A two-way self-regulating return valve is connected in parallel to the inlet and outlet of the hydraulic pump. The two-way self-regulating return valve includes: The valve body has internal connecting channels, sockets, and multiple oil passages; The return valve core is disposed in the communication channel and can move in the socket under the pressure of the liquid oil. It is used to control the connection between different oil passages and realize the reversal, sealing or throttling of the first control oil circuit and the second control oil circuit. When the motor rotates forward, the oil in the tank controls the cylinder to rise through the first control oil circuit. When the motor rotates in reverse, the oil in the tank controls the cylinder to rise through the second control oil circuit. The bidirectional self-controlled return oil valve controls the output pressure in the first and second control oil circuits.

[0008] In some embodiments, the first control oil route is formed by sequentially connecting the oil tank, the hydraulic pump, the first filter screen, and the bottom of the oil cylinder; The second control oil route is formed by sequentially connecting the oil tank, the hydraulic pump, the second filter screen, and the top of the oil cylinder.

[0009] In some embodiments, a hydraulic lock is also included, the hydraulic lock connecting the first filter outlet and the second filter outlet, the hydraulic lock including a third check valve connected between the first filter outlet and the bottom of the oil tank and a fourth check valve connected between the second filter outlet and the top of the oil tank, the third check valve and the fourth check valve being both pilot-operated check valves.

[0010] In some embodiments, a first check valve and a second check valve are also included, with the inlet and outlet of the hydraulic pump connected to the oil tank via the first check valve and the second check valve, respectively.

[0011] In some embodiments, a first relief valve and a second relief valve are also included. The inlet of the first relief valve is connected to the oil passage between the first filter screen and the hydraulic lock, and the inlet of the second relief valve is connected to the oil passage between the second filter screen and the hydraulic lock. The outlets of both are connected to the oil tank.

[0012] In some embodiments, the oil passage includes a first oil passage connecting one section of the connecting channel, a second oil passage connecting the other connecting channel, and a third oil passage, the first oil passage connecting between the hydraulic pump outlet and the first filter inlet, the second oil passage connecting between the hydraulic pump inlet and the second filter inlet, and the third oil passage connecting to the oil tank.

[0013] In some embodiments, the bidirectional self-controlled return valve further includes two elastic elements, which are respectively located on both sides of the socket and abut against the return valve core, so that the return valve core is centered in the socket when there is no pressure.

[0014] In some embodiments, the return valve core includes a connecting rod and two sealing heads, which are respectively connected to both ends of the connecting rod. The size of the sealing head is larger than the size of the insertion hole, so that when the return valve core moves, the sealing head can block the end of the insertion hole to form a seal.

[0015] In some embodiments, the sealing head has a first sealing surface at one end near the insertion hole, and the insertion hole has a second sealing surface at the end. When the return valve core moves, the first sealing surface and the second sealing surface abut against each other to form a seal.

[0016] In some embodiments, the first sealing surface is a tapered surface disposed on the sealing head, and the second sealing surface is a tapered concave surface disposed at the end of the insertion hole.

[0017] In some embodiments, the third oil passage connects from the side to the middle of the socket.

[0018] This invention utilizes the system's own working pressure to drive the bidirectional self-controlled return oil valve to switch directions, achieving complete automation of oil circuit switching and return oil management without requiring any external control signals or components, thus greatly simplifying the system.

[0019] This invention provides a preset, low-resistance return oil channel for the large amount of return oil generated when the cylinder retracts by automatically switching the position of the bidirectional self-controlled return oil valve, fundamentally avoiding system pressure buildup and energy waste, and ensuring stable and energy-saving operation.

[0020] The bidirectional self-controlled return valve of this utility model has a unique annular gap design, which generates a significant throttling effect before the return valve core moves, greatly limiting the leakage of liquid oil and ensuring that control pressure can be quickly established even at a small flow rate (as low as 0.4L / min), so as to drive the return valve core to reliably switch direction, making it possible to achieve precise control using a low-cost gear pump.

[0021] This invention integrates reversing, throttling, and sealing functions into a single bidirectional self-controlled return valve. The overall structure is compact and can be integrated as a module within the main valve block, reducing external connections and leakage points. A hard sealing pair ensures reliable sealing during operation, while a symmetrical spring design ensures stability in the neutral position.

[0022] This invention eliminates the need for expensive solenoid valves and control systems, allowing the use of low-cost pumps and significantly reducing manufacturing costs. The return valve core and spring can be removed from both ends of the valve body for easy maintenance. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a power unit in the prior art; Figure 2 This is a schematic diagram of the structure of a dual-action power unit in this utility model; Figure 3 This is a front view of the bidirectional self-controlled oil return valve in this utility model; Figure 4 This is a left view of the bidirectional self-controlled oil return valve of this utility model; Figure 5 for Figure 4 A schematic diagram of the cross-sectional structure cut along the AA direction; Figure 6 for Figure 5 A magnified structural diagram of position B in the middle; Figure 7 This is a partial structural diagram of the return oil valve core moving to the right within the valve body under the pressure of the liquid oil in this utility model. Figure 8 This is a partial structural diagram of the return oil valve core moving to the left within the valve body under the pressure of the liquid oil in this utility model. Figure 9 This is a schematic diagram of the return oil valve core in this utility model. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] It should be noted that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0027] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "fixation," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between the components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0028] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0029] In the above description, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0030] Figure 2 This is a schematic diagram of the overall structure of a dual-action power unit according to the present invention.

[0031] like Figures 2 to 9As shown, a dual-acting power unit can be externally connected to a hydraulic cylinder 10 to control the output of the hydraulic cylinder 10. It includes a two-way self-regulating return valve 9, a hydraulic lock 8, a motor 2, a hydraulic pump 3, a first filter screen 6, a second filter screen 7, and an oil tank 1. The oil tank 1, hydraulic pump 3, first filter screen 6, hydraulic lock 8, and the bottom of the hydraulic cylinder 10 are connected sequentially to form a first control oil circuit. The oil tank 1, hydraulic pump 3, second filter screen 7, hydraulic lock 8, and the top of the oil tank 1 are connected sequentially to form a second control oil circuit. The motor 2 is connected to the hydraulic pump 3 and can control the hydraulic pump 3 to draw oil from the oil tank 1. The two-way self-regulating return valve 9 is connected in parallel to the inlet and outlet of the hydraulic pump 3. The first and second control oil circuits are used to control the output and input power of the hydraulic cylinder 10, respectively. The two-way self-regulating return valve 9 integrates reversing, sealing, and throttling functions, and is connected to the inlet and outlet of the hydraulic pump 3, replacing the traditional method of adding a bypass circuit or direct overflow.

[0032] The double-acting power unit also includes a check valve. The hydraulic pump 3 is connected to the oil tank 1 through the check valve to prevent backflow of hydraulic oil. Specifically, there are two check valves: a first check valve 4 and a second check valve 5. The inlet and outlet of the hydraulic pump 3 are connected to the oil tank 1 through the first check valve 4 and the second check valve 5, respectively. When the motor 2 rotates forward, the hydraulic pump 3 draws oil from the oil tank 1 through the first check valve 4. When the motor 2 rotates in reverse, the hydraulic pump 3 draws oil from the oil tank 1 through the second check valve 5.

[0033] The hydraulic lock 8 can reliably lock the actuator (such as the cylinder 10) in a fixed position when the double-acting power unit stops supplying pressure, preventing it from moving accidentally due to external forces. Specifically, the hydraulic lock 8 includes two sets of pilot-operated check valves, namely a third check valve 81 and a fourth check valve 82. The third check valve 81 is connected to the bottom of the cylinder 10, and the fourth check valve is connected to the top of the cylinder 10. Through the third check valve 81 and the fourth check valve 82, the cylinder 10 is kept in a fixed position when there is no external hydraulic oil. When hydraulic oil flows from the first control oil circuit, the hydraulic oil opens the third check valve 81 by its own pressure and outputs to the bottom of the oil tank 10, causing the cylinder 10 to rise. The fourth check valve 82 is opened by the hydraulic oil in the first control oil circuit, allowing the hydraulic oil at the top of the cylinder 10 to be output. Similarly, when hydraulic oil flows from the second control oil circuit, the hydraulic oil opens the fourth check valve 82 by its own pressure and outputs to the top of the oil tank 10, causing the cylinder 10 to fall. The third check valve 81 is opened by the hydraulic oil in the first control oil circuit, allowing the hydraulic oil at the bottom of the cylinder 10 to be output.

[0034] Among them, see Figures 3 to 7The bidirectional self-controlled return oil valve 9 includes a valve body 91 and a return oil valve core 92 disposed in the valve body 91. The valve body 91 is provided with a connecting channel 94 and multiple oil passages. The oil passages are connected to the first control oil circuit, the second control oil circuit or the oil tank 1. The return oil valve core 92 is installed in the connecting channel 94 and can move within the connecting channel 94 to control the connection between different oil passages.

[0035] Preferably, the connecting channel 94 is provided in two sections, and the two sections of the connecting channel 94 are connected by the socket 93. The return valve core 92 is installed in the socket 93 and can move within the socket 93. When the return valve core 92 is installed in the socket 93, the two ends of the return valve core 92 are provided with sealing heads 922 located in the connecting channels 94 on both sides. When the return valve core 92 moves, the sealing head 922 can block one end of the socket 93, so that the connecting channel 94 at that end is sealed and not connected with the socket 93, thereby controlling the connection or closure between the oil passages.

[0036] Specifically, in this embodiment, the valve body 91 has a generally rectangular parallelepiped structure, such as a valve block forged and precision machined from aluminum alloy. Internal drilling and reaming form oil passages. The insertion hole 93 is a cylindrical insertion hole horizontally arranged within the valve body 91. The connecting channel 94 is horizontally arranged on both the left and right sides of the insertion hole 93, meaning the two connecting channels 94 within the valve body 91 are mirror-symmetrical in shape, with the insertion hole 93 located in the middle of the two connecting channels 94. The valve body 91 has two oil passages: a first oil passage 95 located to the left of the insertion hole 93 and a second oil passage 96 located to the right of the insertion hole 93. Both oil passages have inlet and outlet holes on the side of the valve body 91, allowing oil to enter and exit within the valve body 91. The two oil passages are connected to the two connecting channels 94 respectively. When the two connecting channels 94 are connected via the insertion hole 93, the two oil passages can also be connected. The return valve core 92 moves within the insertion hole 93, opening or closing the insertion hole 93 to connect or close the two oil passages.

[0037] Preferably, the first oil passage 95 is connected between the outlet of the hydraulic pump 3 and the inlet of the first filter screen 6 in the first control oil circuit, and the second oil passage 96 is connected between the inlet of the hydraulic pump 3 and the inlet of the second filter screen 7 in the second control oil circuit. That is, the bidirectional self-controlled return valve 9 is used to connect the outlet and inlet of the hydraulic pump 3.

[0038] Preferably, both oil passages are connected to the connecting channel 94 from the side. Specifically, in this embodiment, both the first oil passage 95 and the second oil passage 96 are provided with inlet holes on the front side of the valve body 91.

[0039] Preferably, the return valve core 92 further includes a connecting rod 921, and two sealing heads 922 are provided. The two sealing heads 922 are respectively connected to the two ends of the connecting rod 921, so that when the return valve core 92 is installed in the insertion hole 93, the connecting rod 921 moves within the insertion hole 93, and the sealing heads 922 connected to its two ends are respectively located in the connecting channels 94 on both sides of the insertion hole 93. The size of the sealing head 922 is larger than the size of the insertion hole 93, so that when the connecting rod 921 moves within the insertion hole 93, the sealing head 922 connected to its end can block the end of the insertion hole 93 to form a seal. Specifically, in this embodiment, the size of the connecting rod 921 is slightly smaller than the size of the insertion hole 93, so that the connecting rod 921 can move within the insertion hole 93, and the two ends of the connecting rod 921 are respectively connected to two hexagonal prism-shaped sealing heads 922. The size of the sealing head 922 is much larger than the size of the insertion hole 93, so that the sealing head 922 can block the insertion hole 93.

[0040] Preferably, the two sealing heads 922 are detachably mounted at both ends of the connecting rod 921. Specifically, in this embodiment, one of the sealing head 922 and the connecting rod 921 has an internal thread, and the other has an external thread. The sealing head 922 and the connecting rod 921 are detachably connected by threaded engagement. Alternatively, in some other embodiments, the sealing head 922 and the connecting rod 921 can also be detachably connected by other methods such as fitting or snap-fit ​​connection.

[0041] The valve body 91 also includes a third oil passage 97, which connects to the insertion hole 93. By moving the return valve core 92, the two oil passages can connect to or not connect to the insertion hole 93, allowing the first oil passage 95 and the second oil passage 96 to connect or not connect with the third oil passage 97. Specifically, in this embodiment, the third oil passage 97 connects from the side of the insertion hole 93 into the insertion hole 93, and is located at the middle of the insertion hole 93 along its length. This ensures that the distance between the oil passages on both sides of the third oil passage 97 is the same, resulting in a consistent oil path and reducing deviation.

[0042] Preferably, the third oil passage 97 is connected to the oil tank 1, which can return excess liquid oil to the oil tank 1.

[0043] The return valve core 92 is also provided with a first sealing surface 9221, and the insertion hole 93 is provided with a second sealing surface 931. When the return valve core 92 moves within the insertion hole 93, the first sealing surface 9221 and the second sealing surface 931 abut against each other, ensuring good sealing between the return valve core 92 and the insertion hole 93 and guaranteeing control accuracy. Specifically, in this embodiment, the first sealing surface 9221 is a first inclined surface provided on the sealing head 922 of the return valve core 92. The first inclined surface is provided at one end of the sealing head 922 near the insertion hole 93, that is, a conical surface is provided on the side of the sealing head 922 near the insertion hole 93. The second sealing surface 931 is a second inclined surface provided at both ends of the insertion hole 93, that is, a conical concave surface is provided at both ends of the insertion hole 93. During the movement of the return valve core 92, the first sealing surface 9221 and the second sealing surface 931 fit together to form a seal, ensuring good sealing performance of the first sealing surface 9221 and the second sealing surface 931 under oil pressure.

[0044] Preferably, between the valve body 91 and the return valve core 92, since the first sealing surface 9221 is the first inclined surface on the sealing head 922 and the second sealing surface 931 is the second inclined surface provided at both ends of the insertion hole 93, when the return valve core 92 is centered in the insertion hole 93, a uniform annular gap is formed between the first sealing surface 9221 and the second sealing surface 931, so that the oil can be throttled when passing through this position.

[0045] Preferably, the valve body 91 is further provided with an elastic element 98. The elastic element 98 can center the return valve core 92 within the insertion hole 93, so that when there is no pressure, neither of the two oil passages is connected to the third oil passage 97. Moreover, when the return valve core 92 moves, it needs to overcome the elastic force of the elastic element 98, so that the oil passages of the valve body 91 have a certain pressure during control, which facilitates control and can also control small flow oil circuits. Specifically, in this embodiment, the elastic element 98 is a spring, which is provided in two parts. The two springs abut against the return valve core 92 on both sides of the insertion hole 93, so that the return valve core 92 is centered within the insertion hole 93 under the action of the two springs.

[0046] When the bidirectional self-controlled return valve 9 is working, after the hydraulic oil enters the first oil passage 95, the oil pressure acts on the sealing head 922 on the left side of the return valve core 92. Some oil leaks through the return valve core 92 to the third oil passage 97. The throttling surface of the annular gap acts as a throttling surface, reducing oil leakage and allowing the hydraulic pump 3 to build up pressure instantly and quickly. This pressure overcomes the elastic force of the right spring, and the hydraulic oil pushes the return valve core 92 to the opposite side until the sealing head 922 on the left side is tightly pressed against the sealing surface of the valve body 91, forming a reliable seal (see...). Figure 7At this time, the return valve core 92 is in the first working position, blocking the connection between the first oil passage 95 and the third oil passage 97, while simultaneously opening the second oil passage 96 and the third oil passage 97. Similarly, after the liquid oil enters the second oil passage 96, it pushes the return valve core 92 to the left until the sealing head 922 on the right side is tightly pressed against the sealing surface of the valve body 91 (see...). Figure 8 At this time, the return valve core 92 is in the second working position. The return valve core 92 blocks the connection between the second oil passage 96 and the third oil passage 97, and at the same time opens the first oil passage 95 and the third oil passage 97.

[0047] The bidirectional self-controlled return valve 9 also includes a plug 99. The two ends of the connecting channel 94 extend to the edge of the valve body 91 and completely penetrate the valve body 91. The plug 99 is provided with two connecting channels 94 respectively, so that the return valve core 92 and the elastic element 98 in the connecting channel 94 can be removed for maintenance and cleaning.

[0048] Preferably, both the first and second control oil circuits are equipped with relief valves. These relief valves allow pressure relief when the oil pressure in the circuit exceeds a predetermined pressure. Specifically, there are two relief valves: a first relief valve 10 and a second relief valve 11. The inlet of the first relief valve 10 is connected between the outlet of the first filter screen and the inlet of the hydraulic lock 8, and its outlet is connected to the oil tank 1. The inlet of the second relief valve 11 is connected between the outlet of the second filter screen and the hydraulic lock 8, and its outlet is connected to the oil tank 1. In the first control oil circuit, when the pressure is too high, the excess oil can be returned to the oil tank 1 through the first relief valve 10. Similarly, in the second control oil circuit, when the pressure is too high, the excess oil can be returned to the oil tank 1 through the second relief valve 11. In this utility model, the pressure in the first and second control oil circuits is mainly controlled by the bidirectional self-controlled return oil valve 9. The first relief valve 10 and the second relief valve 11 are mainly designed to prevent special situations where the pressure exceeds the control pressure of the bidirectional self-controlled return oil valve 9.

[0049] The double-acting power unit in this utility model is used as follows: When motor 2 rotates forward, hydraulic pump 3 draws oil from oil tank 1 through second check valve 5. The hydraulic oil discharged by hydraulic pump 3 enters first oil passage 95, and the internal pressure of second oil passage 96 decreases instantaneously. At the same time, the annular gap between return valve core 92 and socket 93 acts as a throttling device, reducing oil leakage and allowing hydraulic pump 3 to build up pressure quickly and instantaneously. The hydraulic oil pushes return valve core 92 to the opposite side, forming a sealing surface with valve body 91. First oil passage 95 is disconnected from third oil passage 97, while second oil passage 96 is connected to third oil passage 97. First check valve 4 is closed, and hydraulic oil passes through first filter screen and then through hydraulic lock 8 to the bottom of cylinder 10, pushing cylinder 10 to rise. The oil at the top of cylinder 10 returns to second oil passage 96 and third oil passage 97 through hydraulic lock 8 and second filter screen, and finally returns to oil tank 1.

[0050] When motor 2 reverses, hydraulic pump 3 draws oil from the first check valve 4. The hydraulic oil discharged by hydraulic pump 3 enters the second oil passage 96, and the internal pressure of the first oil passage 95 decreases instantaneously. At the same time, the annular gap between the return valve core 92 and the socket 93 acts as a throttling mechanism, reducing oil leakage and allowing hydraulic pump 3 to quickly build up pressure. The hydraulic oil pushes the return valve core 92 to move to the opposite side, forming a sealing surface with the valve body 91. The second oil passage 96 is disconnected from the third oil passage 97, while the first oil passage 95 is connected to the third oil passage 97. The second check valve 5 is closed, and the hydraulic oil passes through the second filter screen and then through the hydraulic lock 8 to enter the top of the cylinder 10, pushing the cylinder 10 down. The oil at the bottom of the cylinder 10 returns to the first oil passage 95 through the hydraulic lock 8 and the first filter screen. At this time, the amount of oil returned is greater than the amount required by hydraulic pump 3, and the excess must be discharged. Due to the presence of the return valve, the first oil passage 95 is connected to the third passage, and the excess oil is discharged from here, finally returning to the oil tank 1.

[0051] During this process, the annular gap between the return valve core 92 and the insertion hole 93 plays a throttling role, and the valve core can also achieve free reversal under low flow conditions to meet the low flow conditions (≤0.4L / min).

[0052] The dual-acting power unit of this utility model has a bidirectional self-controlled return oil valve 9 in the oil circuit, which integrates the functions of reversing, sealing, and throttling. It replaces the traditional method of adding a bypass circuit or direct overflow. It achieves sealing valve, instantaneous throttling, circuit opening and closing, and control of fluid flow direction through its own hydraulic power and pressure.

[0053] The above descriptions are merely some embodiments of this utility model. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of this utility model, and all such modifications and improvements fall within the protection scope of this utility model.

Claims

1. A double-acting power unit for hydraulic cylinder lifting, characterized in that, include: The first control oil circuit connects the oil tank to the bottom of the oil cylinder; The second control oil circuit connects the oil tank to the top of the oil cylinder; A hydraulic pump is connected to a motor and is connected between the first control oil circuit and the second control oil circuit. Driven by the motor, the hydraulic pump is used to draw oil from the oil tank and deliver the liquid oil to the first control oil circuit or the second control oil circuit. A first check valve and a second check valve, wherein the inlet and outlet of the hydraulic pump are respectively connected to the oil tank via the first check valve and the second check valve; and A two-way self-regulating return valve is located at the inlet and outlet of the hydraulic pump. The two-way self-regulating return valve includes: The valve body has internal connecting channels, sockets, and multiple oil passages; The return valve core is disposed in the communication channel and can move in the socket under the pressure of the liquid oil. It is used to control the connection between different oil passages and realize the reversal, sealing or throttling of the first control oil circuit and the second control oil circuit. When the motor rotates forward, the oil in the tank controls the cylinder to rise through the first control oil circuit. When the motor rotates in reverse, the oil in the tank controls the cylinder to fall through the second control oil circuit. The bidirectional self-controlled return oil valve controls the output pressure in the first and second control oil circuits.

2. The dual-action power unit according to claim 1, characterized in that, The first control oil route is formed by sequentially connecting the oil tank, the hydraulic pump, the first filter screen, and the bottom of the oil cylinder. The second control oil route is formed by sequentially connecting the oil tank, the hydraulic pump, the second filter screen, and the top of the oil cylinder.

3. The dual-action power unit according to claim 2, characterized in that, It also includes a hydraulic lock, which connects the first filter outlet and the second filter outlet. The hydraulic lock includes a third check valve connected between the first filter outlet and the bottom of the oil tank and a fourth check valve connected between the second filter outlet and the top of the oil tank. Both the third check valve and the fourth check valve are pilot-operated check valves.

4. A dual-action power unit according to claim 3, characterized in that, It also includes a first relief valve and a second relief valve. The inlet of the first relief valve is connected to the oil circuit between the first filter screen and the hydraulic lock, and the inlet of the second relief valve is connected to the oil circuit between the second filter screen and the hydraulic lock. The outlets of both are connected to the oil tank.

5. A dual-action power unit according to any one of claims 2-4, characterized in that, The oil passage includes a first oil passage connecting one section of the connecting channel, a second oil passage connecting the other connecting channel, and a third oil passage. The first oil passage is connected between the hydraulic pump outlet and the first filter inlet, the second oil passage is connected between the hydraulic pump inlet and the second filter inlet, and the third oil passage is connected to the oil tank.

6. A dual-action power unit according to claim 5, characterized in that, The bidirectional self-controlled return valve also includes two elastic elements, which are located on both sides of the socket and abut against the return valve core, so that the return valve core is centered in the socket when there is no pressure.

7. A dual-action power unit according to claim 5, characterized in that, The return valve core includes a connecting rod and two sealing heads. The two sealing heads are respectively connected to the two ends of the connecting rod. The size of the sealing head is larger than the size of the insertion hole, so that when the return valve core moves, the sealing head can block the end of the insertion hole to form a seal.

8. A dual-action power unit according to claim 7, characterized in that, The sealing head has a first sealing surface at one end near the insertion hole, and the insertion hole has a second sealing surface at the end. When the return oil valve core moves, the first sealing surface and the second sealing surface abut against each other to form a seal.

9. A dual-action power unit according to claim 8, characterized in that, The first sealing surface is a tapered surface provided on the sealing head, and the second sealing surface is a tapered concave surface provided at the end of the insertion hole.

10. A dual-action power unit according to claim 5, characterized in that, The third oil passage connects from the side to the middle of the insertion hole.

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