A check valve and hydraulic tool

Abstract

The present invention belongs to the technical field of electric hydraulic tools, and relates to a check valve and a hydraulic tool. The check valve includes a check valve body and a check valve core. The check valve core is movably arranged in the check valve body and divides the inside of the check valve body into a first valve cavity and a second valve cavity. The check valve body is also provided with an oil inlet and an oil outlet that can be connected to the first valve cavity and the second valve cavity respectively. The check valve core includes a base, and the second valve cavity is formed between the side of the base facing the check valve body and the check valve body, and an oil outlet hole is provided between the oil outlet and the second valve cavity. A baffle is provided on one side of the check valve core to limit the movement of the check valve core. The present invention adopts a device to realize oil inlet and oil return, and has a compact structure, which greatly reduces the internal installation space of the hydraulic tool and reduces the weight of the hydraulic tool. The automatic pressure relief valve can be opened and closed by switching the oil inlet and oil return, so that the piston can restart the pressurization work during the reset process, greatly improving the construction efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of electric hydraulic tools and relates to a check valve and a hydraulic tool. Background Art

[0002] Electric hydraulic tools are widely used in construction occasions such as power cable cutting and crimping, pipe crimping, etc. The basic principle is to drive the hydraulic pump to pump oil into the hydraulic chamber through the motor, thereby pushing out the piston and piston rod to work. When the hydraulic system reaches the preset pressure value, the automatic pressure relief valve will be opened, and the piston spring squeezes the piston rod to reset the piston. When the piston is fully reset, the automatic pressure relief valve is closed under the action of the spring and is ready for the next work.

[0003] When the automatic pressure relief valve of the existing electric hydraulic tool (such as the invention patent CN103072124B) is opened and the piston is not completely reset, when the electric hydraulic tool is started again, the oil pumped by the hydraulic pump to the hydraulic cylinder will directly flow back to the oil bag (oil storage device) through the automatic pressure relief valve, and it cannot continue to work. It is necessary to wait for the piston to be completely reset to the initial state before the next work can be carried out. In actual application, the time required for the automatic pressure relief valve of the electric hydraulic tool to open and the piston to reset is relatively long, especially for electric hydraulic tools with longer strokes, which will seriously affect the construction efficiency; at the same time, the existing electric hydraulic tools are generally large in size and heavy in weight, and it is difficult for users to hold them for a long time.

[0004] Therefore, the electric hydraulic tool piston can be restarted during the reset process (at any position), and the automatic pressure relief valve can be closed instantly when restarting, making the function of pressurizing the hydraulic tool and achieving restarting work very important. Summary of the invention

[0005] The present invention proposes a check valve used in a hydraulic tool and capable of restarting and continuously working during the resetting process of an electric hydraulic tool piston, and a hydraulic tool provided with the check valve.

[0006] The object of the present invention is achieved in that:

[0007] A check valve comprises a check valve body and a check valve core, wherein the check valve core is movably arranged in the check valve body and divides the interior of the check valve body into a first valve chamber and a second valve chamber; an oil inlet passage and an oil outlet passage which can be respectively connected to the first valve chamber and the second valve chamber are also opened in the check valve body; the check valve core comprises a base, and the second valve chamber is formed between the base and the check valve body on one side facing the check valve body, and an oil outlet hole is arranged between the oil outlet passage and the second valve chamber; a baffle is arranged on one side of the check valve core to limit the movement of the check valve core.

[0008] It is further configured that a first inclined surface is formed on the inner wall of the check valve body located outside the oil outlet hole, and a second inclined surface is formed on the outer end of the base, and when the base moves to be opposite to the first inclined surface and the second inclined surface, an oil outlet is formed between the first inclined surface and the second inclined surface; when the base moves to be offset from the first inclined surface and the second inclined surface, a first gap for oil liquid to pass through is formed between the outer peripheral surface of the base and the inner wall of the check valve body, and the first gap is connected to the oil outlet hole.

[0009] It is further configured that a fixing part is provided in the oil outlet channel, and a second gap for the oil liquid to pass through is formed between the fixing part and the inner wall of the oil outlet channel; the baffle is provided between the fixing part and the end face of the check valve body, and the projection of one side of the baffle covers a part of the base, so as to limit the movement of the check valve core.

[0010] It is further configured that the check valve core includes a plug, the first valve cavity is formed between the front side of the plug and the check valve body, an oil inlet connected to the first valve cavity is opened on the plug, and the plug moves within the check valve body to achieve connection and cutoff between the oil inlet and the oil inlet channel.

[0011] A hydraulic tool comprises a body, a working head and an oil storage bag. The body is connected to the oil storage bag and the working head. A hydraulic chamber, a pressure relief valve and a hydraulic pump for pumping oil in the oil storage bag into the hydraulic chamber are arranged in the body. The hydraulic chamber is provided with the above-mentioned check valve. An oil return channel is also opened in the body, and the oil return channel connects the oil outlet channel and the pressure relief valve.

[0012] It is further configured that the fixing member is a screw, which passes through the oil outlet passage and is fixedly connected to the body.

[0013] It is further configured that a one-way valve is provided between the check valve and the hydraulic pump, a first seal is provided between the end surface of the check valve body facing the one-way valve and the inner wall of the hydraulic chamber, and a second seal is provided between the circumferential surface of the end of the check valve body facing the one-way valve and the inner wall of the hydraulic chamber.

[0014] It is further configured that a center line of the one-way valve and a center line of the check valve core are located on a straight line.

[0015] It is further configured that the one-way valve includes a valve seat, a valve body, and a valve core and a spring arranged between the valve seat and the valve body, the valve seat is provided with a through hole, the spring abuts between the valve core and the valve body, and under the elastic force of the spring, one end face of the valve core can abut against the end face of the valve seat to form a sealing surface; a plurality of flow holes are distributed in the valve body, and when the upper end face of the valve core is separated from the lower end face of the valve seat, the flow hole and the through hole are connected.

[0016] It is further configured that a mounting hole for mounting the pressure relief valve is opened in the body, the pressure relief valve comprises a pressure relief valve seat, a valve needle and a pressure relief piston, the pressure relief valve seat is mounted in the mounting hole, a valve needle is movably arranged on the pressure relief valve seat, the upper end of the valve needle is connected to the pressure relief piston, and a pressure relief spring is sleeved on the outer side of the valve needle;

[0017] An oil groove is provided on the circumferential surface of the pressure relief piston, an oil inlet hole is provided on the upper end surface of the pressure relief piston, the oil inlet hole is connected to the oil groove, and a first oil return hole and a second oil return hole are provided on the main body between the mounting hole and the oil storage bag.

[0018] Compared with the prior art, the present invention has the following outstanding and beneficial technical effects:

[0019] The check valve of the present invention comprises a check valve body and a check valve core. An oil inlet passage and an oil outlet passage are provided on the check valve body. The oil inlet passage and the oil outlet passage are switched with each other by moving the check valve core in the check valve body. Oil inlet and oil return can be achieved with one device. The structure is compact, which greatly reduces the internal installation space of the hydraulic tool and reduces the weight of the hydraulic tool. The automatic pressure relief valve can be opened and closed by switching the oil inlet and oil return, so that the piston can restart the pressurization work during the resetting process, thereby saving waiting time and greatly improving the construction work efficiency.

[0020] The check valve body and the check valve core of the present invention are provided with a first gap at the second valve cavity. During operation, part of the oil can enter the first gap, so that the check valve core can move more smoothly and sensitively to avoid getting stuck.

[0021] When the check valve of the present invention is installed in a hydraulic tool, it is directly fixedly connected to the body of the hydraulic tool through the fixing piece through the oil outlet passage, and a second gap is formed between the outer periphery of the fixing piece and the inner wall of the oil outlet passage, so that the oil can still be discharged from the oil outlet passage there, thereby eliminating the need to provide an additional connecting hole on the check valve body for connecting the check valve to the hydraulic tool body, greatly reducing the size of the check valve, reducing the process steps, reducing costs, reducing the quality of the entire hydraulic tool, and making it easier for users to work with the hydraulic tool.

[0022] When the check valve of the present invention is installed inside the hydraulic tool body, the center lines of the one-way valve and the check valve core are set to be in a straight line, which reduces the stroke of oil entry and makes the oil enter more quickly. In addition, the oil circuit distribution is more reasonable, which reduces the volume of the entire hydraulic tool body and helps to achieve lightweight and miniaturization of the hydraulic tool.

[0023] The hydraulic tool of the present invention is provided with an oil groove and an oil inlet hole on the pressure relief piston of the pressure relief valve, which allows oil to enter and flow out from the second oil return hole, and is used in conjunction with the first oil return hole to greatly improve the oil return efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural diagram of the hydraulic tool of the present invention.

[0025] Figure 2 yes Figure 1 A partial enlarged view of point A.

[0026] Figure 3 yes Figure 2 A partial enlarged view of point B.

[0027] Figure 4 It is a cross-sectional view of the check valve of the present invention when the oil inlet valve port is closed.

[0028] Figure 5 yes Figure 4 A partial enlarged view of point C.

[0029] Figure 6 It is one of the cross-sectional views of the hydraulic tool of the present invention in its initial state.

[0030] Figure 7 This is the second cross-sectional view of the hydraulic tool of the present invention in its initial state.

[0031] Figure 8 It is a cross-sectional view of the pressure relief valve structure of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to specific embodiments of the present invention. Figure 1-Figure 8 :

[0033] A check valve, such as Figure 2 As shown, it includes a check valve body 1 and a check valve core 2, the check valve core 2 is movably set in the check valve body 1 and divides the inside of the check valve body 1 into a first valve chamber 31 and a second valve chamber 32, the check valve core 2 includes an integrally arranged base 21 and a plug 22, the first valve chamber 31 is formed between the end of the plug 22 away from the base 21 and the check valve body 1, because the outer diameter of the base 21 is larger than the outer diameter of the plug 22, there is an obvious retracted platform at the connection between the base 21 and the plug 22, and the second valve chamber 32 is formed between the retracted platform and the check valve body 1. An oil inlet passage 11 and an oil outlet passage 12 which can be connected to the first valve chamber 31 and the second valve chamber 32 respectively are also provided in the check valve body 1, and an oil outlet hole 13 is provided between the oil outlet passage 12 and the second valve chamber 32; when the check valve body 1 moves toward the direction where the first valve chamber 31 is located, the volumes of the first valve chamber 31 and the second valve chamber 32 gradually decrease; conversely, when the check valve body 1 moves in the direction away from the first valve chamber 31, the volumes of the second valve chamber 32 and the first valve chamber 31 gradually increase.

[0034] like Figure 3 and Figure 5As shown, an oil outlet mechanism connected to the oil outlet passage is provided between the check valve body and the check valve core, and the oil outlet amount of the oil outlet mechanism changes with the movement of the check valve core, and the structure of the oil outlet mechanism is as follows: a first inclined surface 14 is formed at the inner wall of the check valve body 1 located outside the oil outlet hole 13, and a second inclined surface 24 is formed at the outer end of the base 21. When the base 21 moves to the point where the first inclined surface 14 is opposite to the second inclined surface 24, an oil outlet 15 is formed between the first inclined surface 14 and the second inclined surface 24, and an oil outlet valve port is formed between the oil outlet 15 and the second valve cavity 32; when the base 21 moves to the point where the first inclined surface 14 is staggered with the second inclined surface 24, a first gap 33 for oil supply liquid to pass through is formed between the outer peripheral surface of the base 21 and the inner wall of the second valve cavity 32, and the first gap 33 is connected to the oil outlet hole 13. The provision of the first gap 33 can also make the movement of the check valve core 2 in the check valve body more flexible to avoid getting stuck.

[0035] In addition, the width of the oil outlet 15 is greater than the width of the first gap 33, that is, Figure 4 and Figure 5 As shown, when the check valve core 2 moves toward the first valve chamber 31 to the maximum stroke, the oil outlet 15 is completely opened to discharge oil in a large amount. At this time, the closed volume of the second valve chamber 32 gradually decreases, and the oil outlet valve port is opened; Figure 2 and Figure 3 As shown, at this time, when the base of the check valve core 2 moves in the direction away from the first valve chamber 31, the first inclined surface 14 and the second inclined surface 24 are offset, the oil outlet 15 gradually disappears and closes, and the first gap is gradually formed. At this time, the closed volume of the second valve chamber 32 gradually increases, and the oil outlet valve port is closed. However, due to the existence of the first gap 33, a small amount of oil can still pass through the oil outlet hole 13 into the oil outlet channel 12.

[0036] A fixing part 18 is provided in the oil outlet passage 12, and a second gap is formed between the fixing part 18 and the inner wall of the oil outlet passage 12 for the oil to pass through. The oil enters the second gap through the oil outlet hole to realize the oil discharge. The fixing part is directly passed through the oil outlet passage 12 to install the check valve body into the main body of the hydraulic tool, so that there is no need to open an additional oil outlet channel or drill additional holes on the check valve body to install the fixing part, thereby reducing the volume of the entire check valve body and the number of process steps. A baffle 19 is provided between the fixing part 18 and the end face of the check valve body 1, and the projection of one side of the baffle 19 covers a portion of the base 21, which is used to limit the movement of the check valve core 2. Figure 2 and Figure 3 As shown, when the outer end surface of the base 21 moves in a direction away from the first valve chamber 31 until it abuts against the baffle 19, the check valve core 2 reaches the maximum stroke, and the baffle 19 plays a good blocking role to prevent the check valve core 2 from separating from the check valve body 1.

[0037] The plug 22 is provided with an oil inlet 23 connected to the first valve chamber 31, and an oil inlet valve port is formed between the oil inlet 23 and the oil inlet passage 11. The plug 22 moves in the check valve body 1 to achieve connection and disconnection between the oil inlet 23 and the oil inlet passage 11, that is, to achieve opening and closing of the oil inlet valve port.

[0038] A hydraulic tool such as Figure 1 and Figure 6 As shown, it includes a main body 4, a working head 5 and an oil storage bag 6. The main body 4 is connected to the oil storage bag 6 and the working head 5. A hydraulic chamber 41, a pressure relief valve 7 and a hydraulic pump 8 for pumping the oil in the oil storage bag 6 into the hydraulic chamber 41 are arranged in the main body 4. A plunger 51, a plunger rod 52 and a working plunger spring 53 are arranged at the front end of the hydraulic chamber 41 toward the working head 5. After the oil is pumped into the hydraulic chamber 41, the plunger 51 and the plunger rod 52 can be pushed to move toward the working head 5, so as to perform work such as crimping or shearing.

[0039] The hydraulic pump 8 works under the control of the motor. An oil inlet valve 61 and a filter are provided at the connection between the main body 4 and the oil storage bag 6. An oil inlet channel 45 is provided near the oil inlet valve of the main body 4. The hydraulic pump 8 is started under the drive of the motor, and the oil in the oil storage bag 6 flows through the oil inlet channel and is pumped into the hydraulic chamber 41, thereby pushing the plunger 51 and the plunger rod 52 to cooperate with the working head 5 to crimp or shear the pipeline. The above-mentioned check valve is provided in the hydraulic chamber 41, and an oil return channel 42 is also provided in the main body 4. The oil return channel 42 connects the oil outlet channel 12 and the pressure relief valve 7. When the pressure relief valve is opened, the oil enters the oil return channel 42 through the oil outlet channel 12 and returns to the oil storage bag 6 through the pressure relief valve.

[0040] Specifically, a mounting cavity is provided on one side of the hydraulic chamber 41, and the check valve is installed in the mounting cavity, and the fixing part is a screw, which passes through the oil outlet channel 12 and is fixedly connected to the main body 4; the main body is provided with a one-way valve 9 on one side of the check valve, and the hydraulic pump 8 is provided between the one-way valve 9 and the oil inlet channel 45, and the one-way valve 9 is opened by pumping oil through the hydraulic pump 8 to allow the oil to enter the hydraulic chamber 41; a first sealing member 16 is provided between the end surface of the check valve body 1 at one end facing the one-way valve 9 and the inner wall of the hydraulic chamber 41, and a second sealing member 17 is provided between the circumferential surface of the check valve body 1 at one end facing the one-way valve 9 and the inner wall of the hydraulic chamber 41.

[0041] like Figure 7 As shown, the center line of the one-way valve 9 and the center line of the check valve core 2 are located on a straight line.

[0042] The one-way valve 9 includes a valve seat 91, a valve body 92, a valve core 93 and a spring 94 arranged between the valve seat 91 and the valve body 92. The valve seat 91 is provided with a through hole 97, and the spring 94 abuts between the valve core 93 and the valve body 92. Under the elastic force of the spring 94, one end face of the valve core 93 can abut against the end face of the valve seat 91 and form a sealing surface; a plurality of flow holes 96 are distributed in the valve body 92. When oil enters the through hole 97, it acts on the valve core 93 and pushes the valve core 93. When the end face of the valve core 93 is separated from the end face of the valve seat 91, the flow hole 96 is connected with the through hole 97, and the oil flows out through the flow hole 96.

[0043] The body 4 is provided with a mounting hole 46 for mounting the pressure relief valve 7. Figure 8 As shown, the pressure relief valve 7 includes a pressure relief valve seat 71, a valve needle 72 and a pressure relief piston 73. The pressure relief valve seat 71 is installed in the mounting hole 46. A valve needle 72 is movably provided on the pressure relief valve seat 71. The upper end of the valve needle 72 is connected to the pressure relief piston 73, and a pressure relief spring 74 is sleeved on the outer side of the valve needle 72. An oil groove 75 is provided on the circumferential surface of the pressure relief piston 73, and an oil inlet hole 76 is provided on the upper end surface of the pressure relief piston 73. The oil inlet hole 76 is connected to the oil groove 75. A first oil return hole 43 and a second oil return hole 44 are provided on the main body 4 between the mounting hole 46 and the oil storage bag 6. When the oil pushes the valve needle 72 open, it enters the mounting hole 46, pushes the valve needle 72 and the pressure relief piston 73 to move, and the oil enters the oil groove 75 along the oil inlet hole 76. When the valve needle 72 is pushed to open the first oil return hole 43, the oil can flow back to the oil storage bag 6 along the first oil return hole 43. When the valve needle 72 is pushed to open the second oil return hole 44, the oil flows back to the oil storage bag 6 along the first oil return hole 43 and the second oil return hole 44.

[0044] The working principle of the hydraulic tool of the present invention:

[0045] Initial state (see Figure 6 and Figure 7 ), the hydraulic pump stops working, the oil inlet valve 61, the one-way valve 9 and the pressure relief valve 7 are all in a closed state, at this time, the oil inlet port 23 in the check valve and the oil inlet channel 11 are cut off, that is, the oil inlet channel is closed.

[0046] The motor starts to increase the pressure, the hydraulic pump is turned on, and the oil in the oil storage bag 6 is collected through the oil inlet valve 61 and the oil inlet channel 45, and the one-way valve 9 is gradually opened. After the one-way valve 9 is opened, the oil enters the first valve chamber 31 along the one-way valve 9, and the oil gradually pushes the check valve core 2 to move in the direction away from the first valve chamber 31. During the movement, the oil inlet 23 and the oil inlet channel 11 are gradually connected, and the oil can be collected into the hydraulic chamber 41 along the oil inlet 23 and the oil inlet channel 11, thereby pushing the plunger 51 and the plunger rod 52 in the hydraulic chamber 41 to move; at this time, the oil inlet valve 61, the one-way valve 9, and the oil inlet channel 11 are all opened, and the pressure relief valve 7 is still in a closed state.

[0047] The motor continues to pressurize, and after the working head starts to work, the pressure in the hydraulic chamber 41 increases. Since the working head will generate a reaction force (resistance) from the workpiece when working, the motor speed will decrease at this time, and the amount of oil output by the hydraulic pump 8 will gradually decrease. The oil inlet valve 61 and the one-way valve 9 will gradually close, and the check valve core 2 will be moved and reset toward the first valve chamber 31 by the oil in the hydraulic chamber 41, and the oil inlet channel 11 will be gradually closed, and the oil outlet 15 will be gradually formed, so that the oil outlet valve port is opened; the oil enters the oil return channel 42, and after the preset pressure is reached in the oil return channel 42, the pressure relief valve 7 will automatically open, and a large amount of oil will flow along the oil outlet channel 12 to the oil return channel 42, and the oil will flow back to the oil storage bag 6 along the first oil return hole and the second oil return hole. At this time, the plunger 51 and the plunger rod 52 in the hydraulic chamber are gradually reset under the drive of the plunger spring 53.

[0048] At any position during the resetting process of the plunger 51 and the plunger rod 52, if the motor is started again, the hydraulic pump works, and the displacement at the hydraulic pump is greater than the displacement of the oil flowing out of the oil outlet 15, the check valve core 2 will be gradually moved by the oil in the direction away from the first valve chamber 31. During the movement, the oil inlet 23 and the oil inlet channel 11 are gradually connected, and the oil outlet 15 gradually becomes smaller. At this time, since the check valve core 2 moves toward the second valve chamber 32, the oil outlet hole 13 is fully opened, the closed volume here increases, and the pressure relief valve 7 will be closed instantly; the hydraulic pump continuously pumps in oil, so that the oil in the hydraulic chamber 41 continues to increase, and begins to push the plunger 51 and the plunger rod 52 toward the working head to continue working; after continuous pressurization, the above-mentioned pressurization process will be repeated, and after continuous pressurization to the preset pressure of the pressure relief valve 7, it will automatically open to relieve pressure.

[0049] The present invention provides a check valve in the main body so that the plunger can continue to work without having to wait until the plunger is completely reset and then restarted as in the prior art, thus saving a lot of waiting time and improving efficiency.

[0050] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A check valve, characterized in that: The invention comprises a check valve body (1) and a check valve core (2), wherein the check valve core (2) is movably arranged in the check valve body (1) and divides the interior of the check valve body (1) into a first valve chamber (31) and a second valve chamber (32); the check valve body (1) is also provided with an oil inlet passage (11) which can be connected to the first valve chamber (31) and an oil outlet passage (12) which can be connected to the second valve chamber (32); The check valve core (2) comprises a base (21), a second valve cavity (32) is formed between the side of the base (21) facing the check valve body (1) and the check valve body (1), and an oil outlet hole (13) is provided between the oil outlet passage (12) and the second valve cavity (32); A baffle (19) is provided on one side of the check valve core (2) to limit the movement of the check valve core (2); A first inclined surface (14) is formed on the inner wall of the check valve body (1) located outside the oil outlet hole (13), and a second inclined surface (24) is formed on the outer end of the base (21). When the base (21) moves to the point where the first inclined surface (14) is opposite to the second inclined surface (24), an oil outlet (15) is formed between the first inclined surface (14) and the second inclined surface (24); When the base (21) moves to the point where the first inclined surface (14) and the second inclined surface (24) are offset, a first gap (33) through which oil passes is formed between the outer peripheral surface of the base (21) and the inner wall of the check valve body (1), and the first gap (33) is connected to the oil outlet hole (13); A fixing member (18) is provided in the oil outlet passage (12), and a second gap is formed between the fixing member (18) and the inner wall of the oil outlet passage (12) for the oil to pass through.

2. The check valve according to claim 1, characterized in that: The baffle plate (19) is provided between the fixing member (18) and the end surface of the check valve body (1), and the projection of one side of the baffle plate (19) covers a portion of the base (21), so as to limit the movement of the check valve core (2).

3. The check valve according to claim 1 or 2, characterized in that: The check valve core (2) comprises a plug (22); the first valve cavity (31) is formed between the front side of the plug (22) and the check valve body (1); an oil inlet (23) connected to the first valve cavity (31) is provided on the plug (22); the plug (22) moves in the check valve body (1) to achieve connection and disconnection between the oil inlet (23) and the oil inlet passage (11).

4. A hydraulic tool, characterized in that: The invention comprises a body (4), a working head (5) and an oil storage bag (6), wherein the body (4) is connected to the oil storage bag (6) and the working head (5), a hydraulic chamber (41), a pressure relief valve (7) and a hydraulic pump (8) for pumping oil in the oil storage bag (6) into the hydraulic chamber (41) are arranged in the body (4), a check valve according to any one of claims 1 to 3 is arranged in the hydraulic chamber (41), and an oil return channel (42) is also opened in the body (4), and the oil return channel (42) connects the oil outlet channel (12) and the pressure relief valve (7).

5. The hydraulic tool according to claim 4, characterized in that: The fixing member (18) is a screw, which passes through the oil outlet passage (12) and is fixedly connected to the body (4).

6. The hydraulic tool according to claim 4, characterized in that: A one-way valve (9) is provided between the check valve and the hydraulic pump (8), a first sealing member (16) is provided between an end surface of the check valve body (1) facing the one-way valve (9) and an inner wall of the hydraulic chamber (41), and a second sealing member (17) is provided between a circumferential surface of the one-way valve body (1) facing the one-way valve (9) and an inner wall of the hydraulic chamber (41).

7. The hydraulic tool according to claim 6, characterized in that: The center line of the one-way valve (9) and the center line of the check valve core (2) are located on a straight line.

8. The hydraulic tool according to claim 6, characterized in that: The one-way valve (9) comprises a valve seat (91), a valve body (92), a valve core (93) and a spring (94) arranged between the valve seat (91) and the valve body (92); the valve seat (91) is provided with a through hole (97) for oil to enter; the spring (94) is abutted between the valve core (93) and the valve body (92); under the elastic force of the spring (94), the end face of the valve core (93) can abut against the end face of the valve seat (91) to form a sealing surface; the valve body (92) is provided with a plurality of flow holes (96); when the end face of the valve core (93) is separated from the end face of the valve seat (91), the flow holes (96) and the through hole (97) are communicated.

9. The hydraulic tool according to any one of claims 4 to 8, characterized in that: The body (4) is provided with a mounting hole (46) for mounting the pressure relief valve (7). The pressure relief valve (7) comprises a pressure relief valve seat (71), a valve needle (72) and a pressure relief piston (73). The pressure relief valve seat (71) is mounted in the mounting hole (46). A valve needle (72) is movably mounted on the pressure relief valve seat (71). The upper end of the valve needle (72) is connected to the pressure relief piston (73). A pressure relief spring (74) is sleeved on the outer side of the valve needle (72). An oil groove (75) is provided on the circumferential surface of the pressure relief piston (73), an oil inlet hole (76) is provided on the upper end surface of the pressure relief piston (73), and the oil inlet hole (76) is connected to the oil groove (75). A first oil return hole (43) and a second oil return hole (44) are provided on the body (4) between the mounting hole (46) and the oil storage bag (6).

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