Reverse unloading valve

Abstract

A reverse unloading valve, which comprises a valve body. An oil inlet and an oil outlet are provided in the valve body. The oil inlet is communicated with the oil outlet through a connecting passage. A valve core is provided in the connecting passage. A return oil port is further provided in the valve body. A oil passage with adjustable flow rate is provided between the oil outlet and the return oil port along with the movement of the valve core. Since a triangular groove is provided on the valve core, the pressure relief flow rate changes gradually from small to large, thus solving the problems in the prior art that the reverse unloading valve is damaged due to excessive impact stress and the physical and mental health of on-site operators is harmed due to excessive impact noise. At the same time, it unexpectedly solves the problem in the prior art that the hydraulic pump has poor heat dissipation effect due to too small flow rate during the pressure holding process, which further causes abnormal temperature rise.

Description

Technical Field

[0001] The present invention relates to a hydraulic device, and more specifically, to a reverse pressure relief valve for working conditions such as frequent pressure maintenance and reverse in a hydraulic system. Background Art

[0002] The Chinese Patent Office published a utility model patent with the publication number CN204239362U on April 1, 2015. This utility model patent discloses a reverse pressure discharge valve, which is provided with an oil inlet, an oil outlet, and an oil drain port. The oil inlet is communicated with the oil outlet end of a hydraulic pump, and the oil outlet is communicated with a hydraulic actuator. A valve core and a spring are arranged inside the reverse pressure discharge valve, and the valve core abuts against the spring. An inlet guide chamber and an outlet guide chamber are respectively arranged on both sides of the reverse pressure discharge valve. A direct-acting overflow valve is connected between the oil outlet and the oil drain port. When the system needs reverse pressure relief, the hydraulic pump stops pressurizing, the oil pressure in the oil supply pipeline drops to zero, and the valve core quickly switches under the dual action of the oil pressure in the hydraulic actuator and the spring, instantaneously switching the oil inlet pipeline of the hydraulic actuator and the oil drain port from the cut-off state to the connected state. In this way, the reverse pressure relief liquid flow will impact the hydraulic pump and the servo motor, causing them to reverse, thereby generating large impact stresses and impact noises, greatly shortening the service life of the hydraulic pump and the servo motor, and the huge noise is also not conducive to the physical and mental health of on-site operators. Summary of the Invention

[0003] To overcome the above defects, the technical problem to be solved by the present invention is: to provide a reverse unloading valve that can buffer the reverse pressure relief liquid flow, greatly reduce the impact stress and impact noise during reverse pressure relief, thereby protecting the hydraulic pump and the servo motor, and further realizing the extension of the service life of the hydraulic pump and the servo motor, and ensuring the physical and mental health of on-site operators.

[0004] The technical solution of the present invention to solve the problems existing in the prior art is as follows: A reverse unloading valve, which includes a valve body. An oil inlet connected to a hydraulic pump and an oil outlet connected to a hydraulic drive device are provided inside the valve body. The oil inlet is communicated with the oil outlet through a connecting channel inside the valve body. A valve core that can cut off the communication between the oil inlet and the oil outlet is provided in the connecting channel. A return oil port connected to a fuel tank for recovering the oil fluid of the hydraulic system is also provided inside the valve body. An oil passage with adjustable flow rate is provided between the oil outlet and the return oil port of the valve body or the valve core along with the movement of the valve core. When the hydraulic system needs to reverse pressure relief, the hydraulic pump stops pressurizing according to the command requirements. The oil pressure at the oil inlet of the reverse unloading valve drops to zero. The valve core moves towards the oil inlet direction under the push of the high-pressure hydraulic oil in the hydraulic drive device. The high-pressure hydraulic oil in the hydraulic drive device starts to relieve pressure from the oil passage to the return oil port with the flow rate increasing from small to large. When the valve core blocks the oil inlet, the flow rate of the oil passage reaches the maximum. In this way, the process of the flow rate of the oil passage increasing from small to large plays a buffering role in the reverse pressure relief of the high-pressure hydraulic oil in the hydraulic drive device, so that no excessive impact stress and impact noise are formed during the entire reverse pressure relief process, thereby solving the problems existing in the prior art, and can greatly extend the service life of the hydraulic pump and the servo motor, ensuring that the physical and mental health of on-site operators is not affected by the impact noise. After the inventor solved the impact stress and impact noise of the reverse unloading valve existing in the prior art, it was unexpectedly found that another problem existing in the prior art was also solved, that is, during the pressure holding process of the hydraulic drive device, the flow rate required to supplement the internal leakage of the hydraulic drive device was too small, so that the heat generated by the hydraulic pump during the output of the pressure holding micro flow rate could not be carried away by the high-pressure hydraulic oil, resulting in abnormal temperature rise of the hydraulic pump, which was not conducive to maintaining various mechanical properties of the hydraulic pump, and thus the hydraulic pump could not maintain normal operation for a long time. When the hydraulic drive device is in the pressure holding state, due to inevitable small internal leakage of the hydraulic drive device, it is necessary for the hydraulic pump to supplement this part of the flow rate leaked by the hydraulic drive device to ensure the pressure stability of the hydraulic drive device, so that the valve core cannot completely block the oil inlet. Just in this way, the oil passage in the technical solution of the present invention can allow a small amount of high-pressure hydraulic oil to flow from the oil outlet to the return oil port through it. This part of the flow rate plus the internal leakage flow rate of the hydraulic drive device can carry away the heat generated by the hydraulic pump, ensuring the temperature stability of the hydraulic pump, and various mechanical properties of the hydraulic pump can be maintained in the optimal state for a long time to maintain the long-term continuous normal operation of the hydraulic pump.

[0005] The oil passage can be provided on the valve body or on the valve core. As a further technical solution, the oil passage is provided on the valve core. Setting the oil passage on the valve core is convenient for processing, so as to reduce the manufacturing cost.

[0006] The oil passage can be arranged inside the valve core or on the outer surface of the valve core. As a further technical solution, the oil passage is arranged on the outer surface of the valve core. Arranging the oil passage on the outer surface of the valve core is convenient for processing, so as to reduce the manufacturing cost.

[0007] As a further technical solution, the cross-sectional area of one end of the oil passage is larger than that of the other end, and the small end of the cross-section of the oil passage faces the direction of the oil inlet. Such a structural arrangement form can enable the reverse unloading valve to play a buffering role when reverse pressure relief occurs.

[0008] As a further technical solution, an annular groove is provided on the outer surface of the valve core, and the annular groove is communicated with the large end of the oil passage. This is beneficial to arranging a plurality of oil passages circumferentially on the outer surface of the valve core.

[0009] As a further technical solution, the oil passage is a tapered triangular groove. Such a structure is convenient for processing, so as to reduce the manufacturing cost.

[0010] As a further technical solution, the number of the oil passages is six, and the six oil passages are evenly distributed on the outer peripheral surface of the valve core. Such a structural arrangement form is beneficial to dispersing the stress concentration of the valve core and the valve body, and can extend the service life of the valve core and the valve body.

[0011] As a further technical solution, a cavity is also provided in the valve body, the cavity surrounds the outer peripheral side of the valve core, and the cavity is also communicated with the annular groove and the oil return passage respectively.

[0012] As a further technical solution, the end of the connecting passage far from the oil inlet extends outward and penetrates through the valve body. A plug screwed to the valve body is provided at the end of the connecting passage far from the oil inlet. A blind hole is provided in the valve core, and the opening end of the blind hole faces the plug. A spring is provided between the plug and the valve core. One end of the spring abuts against the bottom surface of the blind hole of the valve core, and the other end of the spring abuts against the bottom surface of the pit of the plug. The blind hole is communicated with the oil outlet through a through hole. Making the connecting passage penetrate through the valve body and closing the end of the connecting passage far from the oil inlet with a screwed plug is beneficial to the subsequent maintenance of the valve core. A blind hole is provided in the valve core, the opening end of the blind hole faces the plug, and a spring is arranged between the plug and the valve core. This can ensure the smooth restart after the hydraulic pump stops, and at the same time can ensure that the oil pressure at the oil inlet is slightly higher than the oil pressure in the hydraulic drive device, which is beneficial to the stable pressure holding of the hydraulic drive device. A through hole is provided on the valve core to communicate the blind hole and the oil outlet, so that the high-pressure hydraulic oil in the oil outlet can smoothly enter the blind hole, which is beneficial to the oil pressure balance at both ends of the valve core, can reduce the parameter requirements for the spring, and thus reduce the manufacturing cost of the reverse unloading valve.

[0013] As a further technical solution, an overflow valve is provided between the oil outlet and the oil return port. This can ensure that the reverse unloading valve will not have an abnormal increase in oil pressure.

[0014] In the present invention, six circumferentially arranged and evenly distributed conical triangular grooves are provided on the outer surface of the valve core, so that when the reverse unloading valve is reversely depressurized, it can connect the oil outlet and the oil return port, and as the valve core moves, the depressurization flow rate is transformed into a gradual process from small to large, thus solving the problems existing in the prior art that the reverse unloading valve is damaged due to excessive impact stress and the physical and mental health of on-site operators is damaged due to excessive impact noise. At the same time, it unexpectedly solves the problem existing in the prior art that the hydraulic pump has a poor heat dissipation effect due to too small a flow rate during the pressure holding process, which in turn causes an abnormal increase in temperature. Brief Description of the Drawings

[0015] Figure 1 is a three-dimensional structural schematic diagram of the present invention;

[0016] Figure 2 is a front view structural schematic diagram of the present invention;

[0017] Figure 3 is Figure 2 the sectional view taken along line A-A in

[0018] Figure 4 is a three-dimensional schematic diagram of the valve core in the present invention.

[0019] In the figure: valve body 1, oil inlet 2, oil outlet 3, connecting channel 4, valve core 5, plug 6, blind hole 7, spring 8, through hole 9, triangular groove 10, annular groove 11, oil return port 12, cavity 13, overflow valve 14. Detailed Embodiments

[0020] The present invention will be further described below through specific embodiments in combination with the accompanying drawings of the specification.

[0021] Embodiment: A reverse unloading valve, as shown in the figure, includes a valve body 1. An oil inlet 2 connected to a hydraulic pump and an oil outlet 3 connected to a hydraulic drive device are provided inside the valve body 1. The oil inlet 2 is communicated with the oil outlet 3 through a connecting channel 4 inside the valve body 1. A valve core 5 that can cut off the connection between the oil inlet 2 and the oil outlet 3 is provided in the connecting channel 4. One end of the connecting channel 4 away from the oil inlet 2 extends outward and penetrates the valve body 1. A plug 6 screwed to the valve body 1 is provided at the end of the connecting channel 4 away from the oil inlet 2. A blind hole 7 is provided inside the valve core 5, and the opening end of the blind hole 7 faces the plug 6. A spring 8 is provided between the plug 6 and the valve core 5. One end of the spring 8 abuts against the bottom surface of the blind hole 7 of the valve core 5, and the other end of the spring 8 abuts against the bottom surface of the pit of the plug 6. The blind hole 7 is communicated with the oil outlet 3 through a through hole 9. Six conical triangular grooves 10 are circumferentially and evenly distributed on the outer surface of the valve core 5. The small end of the cross-section of the triangular groove 10 faces the direction of the oil inlet 2. The tip of the triangular groove 10 is communicated with the oil outlet 3 when the reverse unloading valve is in the pressure-holding state. An annular groove 11 communicated with the triangular groove 10 is provided on the outer surface of the valve core 5 at the large end position of the triangular groove 10. An oil return port 12 connected to a fuel tank for recovering the hydraulic system oil is also provided inside the valve body 1. A cavity 13 is also provided inside the valve body 1. The cavity 13 surrounds the outer peripheral side of the valve core 5. The cavity 13 is also communicated with the annular groove 11 and the oil return channel respectively. To ensure the safety of the reverse unloading valve and the hydraulic drive device, an overflow valve 14 is provided between the oil outlet 3 and the oil return port 12.

[0022] The above-described embodiment is only a preferred solution of the present invention, and does not impose any form of limitation on the present invention. There are other variations and modifications without exceeding the technical solutions described in the claims.

[0023] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

Claims

1. A reverse unloading valve, which comprises a valve body. An oil inlet connected to a hydraulic pump and an oil outlet connected to a hydraulic drive device are provided in the valve body. The oil inlet is communicated with the oil outlet through a connecting channel in the valve body. A valve core capable of cutting off the communication between the oil inlet and the oil outlet is provided in the connecting channel. It is characterized in that, The valve body is also provided with an oil return port connected to a fuel tank for recycling hydraulic system oil. Between the oil outlet and the oil return port, the valve body or the valve core is provided with an oil passage with adjustable flow rate along with the movement of the valve core. One end of the connecting passage far from the oil inlet extends outward and penetrates the valve body. A plug screwed to the valve body is provided at the end of the connecting passage far from the oil inlet. A blind hole is provided in the valve core, and the opening end of the blind hole faces the plug. A spring is provided between the plug and the valve core. One end of the spring abuts against the bottom surface of the blind hole of the valve core, and the other end of the spring abuts against the bottom surface of the pit of the plug. The blind hole is communicated with the oil outlet through a through hole. The oil passage is a tapered triangular groove, and the tip of the triangular groove is communicated with the oil outlet when the reverse unloading valve is in the pressure maintaining state.

2. The reverse unloading valve according to claim 1, characterized in that, The oil passage is arranged on the valve core.

3. The reverse unloading valve according to claim 2, characterized in that, The oil passage is arranged on the outer surface of the valve core.

4. The reverse unloading valve according to claim 1 or 2 or 3, characterized in that, The cross-sectional area of one end of the oil passage is larger than that of the other end, and the small end of the cross-section of the oil passage faces the direction of the oil inlet.

5. The reverse unloading valve according to claim 1 or 2 or 3, characterized in that, An annular groove is provided on the outer surface of the valve core, and the annular groove is communicated with the large end of the oil passage.

6. The reverse unloading valve according to claim 1 or 2 or 3, characterized in that, The number of the oil passages is six, and the six oil passages are evenly distributed on the outer peripheral surface of the valve core.

7. The reverse unloading valve according to claim 5, characterized in that, A cavity is also provided in the valve body, and the cavity surrounds the outer peripheral side of the valve core. The cavity is also communicated with the annular groove and the oil return port respectively.

8. The reverse unloading valve according to claim 1 or 2 or 3, characterized in that, An overflow valve is provided between the oil outlet and the oil return port.

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