Speed change valve assembly and engineering machinery

Abstract

The utility model relates to the technical field of engineering machinery, and discloses a speed change valve assembly and engineering machinery. The speed change valve assembly comprises a valve body, a pressure regulating valve and a pressure relief assembly. The pressure regulating valve is movably arranged in the valve cavity of the valve body and is used for communicating the oil inlet and the oil outlet of the valve body; the pressure relief assembly comprises a seat body, an elastic structure and a blocking piece, the seat body is fixed to the pressure relief opening and comprises a pressure relief channel communicating the oil guide cavity with the outer surface of the valve body, the blocking piece is movably contained in the pressure relief channel, and the elastic structure is arranged between the blocking piece and the inner wall of the pressure relief channel; the elastic structure is used for driving the plugging piece to press and cover the pressure relief channel to communicate with the port of the oil guide cavity. The pressure relief assembly can relieve pressure of the oil guide cavity in time when the oil pressure in the oil guide cavity rises, the risk that an oil filter on the upstream of the speed change valve assembly possibly bursts is reduced, and the safety of the system is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of engineering machinery, in particular to a speed change valve assembly and engineering machinery. Background Art

[0002] The speed change valve assembly in construction machinery is mainly responsible for controlling the gear shifting operation of the transmission system to achieve different driving speeds and torque outputs.

[0003] The speed change valve assembly includes a pressure regulating valve, which is arranged at the oil inlet position of the speed change valve assembly and is used to adjust the pressure of the hydraulic oil entering the speed change valve to be constant. In the prior art, due to problems such as low oil cleanliness, the pressure regulating valve may become stuck, resulting in failure of the pressure regulation function, and there is also a risk of bursting of the oil filter on the oil inlet side of the speed change valve. Utility Model Content

[0004] The utility model discloses a speed change valve assembly and engineering machinery. The speed change valve assembly can timely release pressure from an oil guide cavity when a pressure regulating valve is stuck, thereby reducing the risk of an oil filter bursting upstream of the speed change valve assembly and improving the safety of the system.

[0005] In order to achieve the above object, the utility model provides the following technical solutions:

[0006] In a first aspect, the present application provides a speed change valve assembly, comprising: a valve body, a pressure regulating valve and a pressure relief assembly; the valve body has a valve cavity, an oil inlet, an oil outlet, an oil guide cavity and a pressure relief port, the inner wall of the valve cavity is formed with a first annular groove, a second annular groove and a pressure groove, the first annular groove is communicated with the oil inlet and the inlet of the oil guide cavity, the pressure groove is communicated with the outlet of the oil guide cavity, the second annular groove is communicated with the oil outlet, and the pressure relief port is communicated with the oil guide cavity;

[0007] The pressure regulating valve is movably disposed in the valve cavity, and is used to move under the oil pressure of the hydraulic oil in the pressure groove to connect the first annular groove and the second annular groove;

[0008] The pressure relief assembly includes a seat body, an elastic structure and a sealing member, the seat body is fixed at the pressure relief port, the seat body includes a pressure relief channel connecting the oil guide chamber and the outer surface of the valve body, the sealing member can be movably accommodated in the pressure relief channel, the elastic structure is arranged between the sealing member and the inner wall of the pressure relief channel, and the elastic structure is used to drive the sealing member to press and cover the port of the pressure relief channel for connecting the oil guide chamber.

[0009] In the above-mentioned speed change valve assembly, when the pressure regulating valve is stuck, the hydraulic oil pressure in the oil guide chamber is relatively large, which can push the sealing member to leave the port connecting the pressure relief channel and the oil guide chamber, and the oil in the oil guide chamber can be released through the pressure relief channel to achieve pressure relief. When the oil pressure in the oil guide chamber returns to normal, the elastic structure recovers and presses the sealing member to close the port connecting the pressure relief channel and the oil guide chamber to achieve resetting. The pressure relief component can timely relieve the pressure of the oil guide chamber when the oil pressure in the oil guide chamber increases, prevent the oil pressure in the oil guide chamber and the oil inlet from being too high, reduce the risk of bursting the oil filter upstream of the speed change valve assembly, and improve the safety of the system. The detachable structure of the pressure relief component is simple in structure and easy to install, and can also reduce the cost of use and maintenance.

[0010] Optionally, the seat body includes a fixed seat and a sub-seat;

[0011] The fixing seat is fixed to the inner wall of the pressure relief port, and the fixing seat has a first opening groove and a connecting hole, wherein the opening of the first opening groove faces away from the oil guide cavity, and the connecting hole connects the bottom of the first opening groove and the outer wall of the fixing seat facing the oil guide cavity;

[0012] The sub-seat is fixed in the first opening groove, and the sub-seat has a second opening groove and a conducting hole. The second opening groove is connected with the first opening groove to form a space for accommodating the elastic structure. The conducting hole is used to connect the second opening groove with the outer wall of the valve body. The inner diameter of the conducting hole is smaller than the inner diameter of the second opening groove. A first abutting surface for abutting against the elastic structure is formed between the conducting hole and the second opening groove.

[0013] Optionally, the sub-base is connected to the fixing base via threads.

[0014] Optionally, the inner diameter of the connecting hole is smaller than the outer diameter of the blocking piece, and the inner diameter of the first opening groove is larger than the outer diameter of the blocking piece.

[0015] Optionally, the fixing seat further has a transition section connected between the first opening groove and the connecting hole, and the inner wall radius of the transition section is smaller than the inner wall radius of the first opening groove and larger than the inner wall radius of the connecting hole.

[0016] Optionally, the elastic structure includes a spring and a support, one end of the spring abuts against the inner wall of the pressure relief channel, and the other end abuts against the support, and the support is used to support the blocking member.

[0017] Optionally, the support includes a base and a connecting portion, wherein the connecting portion protrudes from the base and is used to be embedded in the coil of the spring, and a second abutting surface for abutting against the spring is formed between the connecting portion and the base.

[0018] Optionally, a concave bearing surface is formed on a side of the base facing away from the connecting portion, and the bearing surface is used to partially accommodate the blocking member.

[0019] Optionally, the speed change valve assembly further includes a sealing ring, which surrounds the pressure relief passage and is arranged between the valve body and the pressure relief component.

[0020] In a second aspect, the present application provides an engineering machine, comprising a hydraulic speed change system, wherein the hydraulic speed change system comprises a hydraulic pump, an oil filter, and a speed change valve assembly as described in any one of the first aspects;

[0021] The oil filter is connected between the hydraulic pump and the oil inlet of the speed change valve assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the principle of a hydraulic speed change system of an engineering machinery provided by an embodiment of the utility model;

[0023] Figure 2a A schematic cross-sectional structure diagram of a speed change valve assembly provided in an embodiment of the utility model;

[0024] Figure 2b A schematic cross-sectional structure diagram of a speed change valve assembly provided in an embodiment of the utility model;

[0025] Figure 3 A schematic cross-sectional structure diagram of a pressure relief component of a speed change valve assembly provided by an embodiment of the utility model;

[0026] Figure 4a A schematic structural diagram of a fixing seat of a pressure relief component of a speed change valve assembly provided in an embodiment of the utility model;

[0027] Figure 4b A schematic cross-sectional structure diagram of a fixing seat of a pressure relief component of a speed change valve assembly provided by an embodiment of the utility model;

[0028] Figure 5a A schematic structural diagram of a sub-seat of a pressure relief component of a speed change valve assembly provided in an embodiment of the utility model;

[0029] Figure 5b A schematic cross-sectional structure diagram of a sub-seat of a pressure relief component of a speed change valve assembly provided by an embodiment of the utility model;

[0030] Figure 6a A schematic structural diagram of a support of a pressure relief component of a speed change valve assembly provided in an embodiment of the utility model;

[0031] Figure 6bA schematic cross-sectional structure diagram of a support of a pressure relief component of a speed change valve assembly provided in an embodiment of the utility model;

[0032] Figure 7 A schematic diagram of the pressure relief principle of a pressure relief component of a speed change valve assembly provided in an embodiment of the utility model.

[0033] Reference numerals:

[0034] 10-speed shift valve assembly; 20-oil filter; 30-hydraulic pump; 1-pressure regulating valve; 11-valve sleeve; 12-valve stem; 13-inner valve core; 14-outer valve core; 15-plug; 101-oil guide channel; 2-valve body; 201-valve cavity; 2011-first annular groove; 2012-second annular groove; 2013-pressure groove; 202-oil inlet; 203-oil outlet; 204-oil guide cavity; 2041-oil inlet channel; 204 2-return oil channel; 205-pressure relief port; 3-pressure relief assembly; 31-seat body; 311-fixed seat; 3111-first opening groove; 3112-connecting hole; 3113-transition section; 312-sub-seat; 3121-second opening groove; 3122-conducting hole; 32-elastic structure; 321-spring; 322-support; 3221-base; 3222-connecting part; 33-blocking piece; 34-sealing ring; 4-auxiliary valve. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0036] The speed change valve assembly is widely used in the hydraulic speed change system of construction machinery such as bulldozers to control the forward, reverse and gear shifting of the bulldozers. Figure 1 The schematic diagram of the structure of a hydraulic transmission system of an engineering machinery provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the hydraulic speed change system of the engineering machinery includes a speed change valve assembly 10, an oil filter 20 and a hydraulic pump 30. The oil inlet of the hydraulic pump 30 is connected to the oil tank, and the oil is pumped out by the hydraulic pump 30 and filtered by the oil filter 20 before entering the speed change valve assembly 10. The speed change valve assembly 10 includes a pressure regulating valve 1, which is used to adjust the pressure of the hydraulic oil entering the speed change valve assembly 10 to a constant value, so that the speed change valve assembly 10 can realize the forward, reverse and neutral, 1st gear, 2nd gear, and 3rd gear of the engineering machinery through the reversing of the joystick.

[0037] In some special cases, the hydraulic oil entering the speed change valve assembly 10 is not clean enough, or is blocked by foreign matter, which may cause the pressure regulating valve 1 to get stuck and the pressure regulating function to fail, and the pressure at the oil inlet position of the speed change valve assembly 10 increases, which may cause the oil filter 20 to burst. In order to solve this problem, the speed change valve assembly 10 provided in the embodiment of the present application has a pressure relief regulating function. When the pressure regulating valve 1 fails, the speed change valve assembly 10 can be depressurized to prevent the oil pressure at the oil inlet position of the speed change valve assembly 10 from being too high and affecting the safety of the oil filter 20.

[0038] like Figure 2a and Figure 2b As shown, a speed change valve assembly 10 provided in an embodiment of the present application includes a pressure regulating valve 1, a valve body 2 and a pressure relief component 3. The valve body 2 has a valve cavity 201, an oil inlet 202, an oil outlet 203, an oil guide cavity 204 and a pressure relief port 205. Among them, the inner wall of the valve cavity 201 is formed with a first annular groove 2011, a second annular groove 2012 and a pressure groove 2013. The first annular groove 2011 is connected with the oil inlet 202 and the oil guide cavity 204, the second annular groove 2012 is connected with the oil outlet 203, and the pressure groove 2013 is connected with the oil guide cavity 204. Exemplarily, the oil guide cavity 204 is connected with the first annular groove 2011 through the oil inlet channel 2041, and is connected with the pressure groove 2013 through the oil return channel 2042, and the pressure relief port 205 is connected with the oil guide cavity 204. With reference to the length direction of the valve cavity 201, the oil inlet 202 and the oil outlet 203 are arranged at intervals along the length direction of the valve cavity 201 and are located on the same side of the valve cavity 201, and the oil guide cavity 204 is located on the other side of the valve cavity 201. Figure 2a and Figure 2b The state shown is for reference, the oil inlet 202 and the oil outlet 203 are located on the upper side of the valve cavity 201, and the oil guide cavity 204 is located on the lower side of the valve cavity 201. The hydraulic oil entering the oil inlet 202 can enter the oil guide cavity 204 through the first annular groove 2011 and the oil inlet channel 2041 of the valve cavity 201, and return to the pressure groove 2013 through the oil return channel 2042. The oil pressure in the oil guide cavity 204 is consistent with the oil pressure of the oil inlet 202.

[0039] The pressure regulating valve 1 can be movably arranged in the valve cavity 201 along the length direction of the valve cavity 201, and one end of the pressure regulating valve 1 is located in the pressure groove 2013. The pressure regulating valve 1 has an oil guide channel 101 for connecting the first annular groove 2011 and the second annular groove 2012. Exemplarily, the pressure regulating valve 1 includes a valve sleeve 11, a valve stem 12, an inner valve core 13, an outer valve core 14, and a plug 15. The valve sleeve 11 can be movably installed in the valve cavity 201 along the length direction of the valve cavity 201, and the valve stem 12 can be movably arranged in the valve sleeve 11 along the length direction of the valve cavity 201. The inner valve core 13 and the outer valve core 14 are arranged in the chamber of the valve stem 12 along the length direction of the valve chamber 201 at intervals. The inner valve core 13 is relatively fixed to the valve stem 12, and the outer valve core 14 is movable along the length direction of the valve chamber 201 relative to the valve stem 12. A hydraulic chamber Q is formed between the inner valve core 13 and the outer valve core 14, and an elastic member is arranged between the inner valve core 13 and the outer valve core 14. The valve sleeve 11, the valve stem 12, and the inner valve core 13 respectively have mutually connected channels, which can connect the first annular groove 2011 with the hydraulic chamber Q, so as to guide the hydraulic oil into the hydraulic chamber Q. The oil guide channel 101 is connected to the channel. The plug 15 is arranged in the valve sleeve 11, one end of the plug 15 abuts against the outer valve core 14, and the other end extends into the pressure groove 2013 of the valve chamber 201.

[0040] In some embodiments, the shift valve assembly 10 may further include an auxiliary valve 4, which may be movably installed in the oil guide chamber 204 and may be used to connect the oil inlet channel 2041 with the oil guide chamber 204 and to connect the oil return channel 2042 with the oil guide chamber 204.

[0041] Combination Figure 2a and Figure 2b As shown, the working principle of the pressure regulating valve 1 is introduced. Figure 2a It can be considered as the initial state of the pressure regulating valve 1. The oil guide channel 101 of the pressure regulating valve 1 includes a hole a on the valve sleeve 11, and the hole a is connected to the oil inlet 202. The channel on the pressure regulating valve 1 can guide the hydraulic oil in the oil guide channel 101 to the hydraulic chamber Q. The hydraulic oil gradually increases in the hydraulic chamber Q until the pressure increases, which can push the inner valve core 13 to move leftward away from the outer valve core 14, and the inner valve core 13 drives the valve stem 12 to move leftward relative to the valve sleeve 11. At the same time, the hydraulic oil enters the oil guide chamber 204 from the oil inlet 202 through the first annular groove 2011 of the valve chamber 201, the oil inlet channel 2041, and the auxiliary valve 4. The hydraulic oil in the oil guide chamber 204 can return to the pressure groove 2013 again through the auxiliary valve 4 and the oil return channel 2042. The hydraulic oil gradually increases in the pressure groove 2013 until the pressure increases, which can push the plug 15, and the plug 15 moves the valve sleeve 11 to the left.

[0042] When the inner valve core 13 moves with the valve stem 12 to Figure 2b At the same time, the plug 15 moves with the valve sleeve 11 to Figure 2bIn the position shown, the oil guide channel 101 of the pressure regulating valve 1 includes a hole a and another hole b on the valve sleeve 11, the hole a is connected to the oil inlet 202, and the hole b is connected to the oil outlet 203. At this time, the oil inlet 202 is equivalent to being connected through the oil guide channel 101 on the pressure regulating valve 1. For the entire pressure regulating valve 1, the valve sleeve 11 moves to the left, the valve stem 12 moves to the left, and the inner valve core 13 moves to the left. There are elastic reset parts, and when the movement of each structure is large enough, the elastic reset part can move the corresponding structure in the direction of recovery, dynamically adjust the oil pressure between the oil inlet 202 and the oil outlet 203, and ensure the balance of oil pressure.

[0043] In some special cases, such as when there are many impurities in the hydraulic oil, the pressure regulating valve 1 may be blocked by foreign matter and cannot move. At this time, it is necessary to timely release the pressure of the hydraulic oil in the oil guide chamber 204 to prevent the oil pressure at the oil inlet 202 from increasing and affecting the safety of the oil filter 20 upstream of the speed change valve assembly 10. The pressure relief component 3 in the embodiment of the present application is used to timely release the pressure of the oil guide chamber 204 when the pressure regulating valve 1 fails.

[0044] like Figure 3 As shown, the pressure relief assembly 3 includes a seat body 31, an elastic structure 32 and a plugging member 33. The seat body 31 is fixed at the pressure relief port 205. The seat body 31 includes a pressure relief channel T connecting the oil guide chamber 204 and the outer surface of the valve body 2. The plugging member 33 can be movably accommodated in the pressure relief channel T. One end of the elastic structure 32 abuts against the inner wall of the pressure relief channel T, and the other end abuts against the plugging member 33 so that the plugging member 33 presses and covers the port t of the pressure relief channel T for connecting the oil guide chamber 204. When the pressure regulating valve 1 is in a normal working state, the elastic structure 32 can provide a pre-tightening force for the plugging member 33, so that the plugging member 33 can block the port t of the pressure relief channel T, and the hydraulic oil in the oil guide chamber 204 can be in the valve body 2 of the speed change valve assembly 10 as shown in FIG. Figure 2a or Figure 2b The flow in the state shown ensures the normal function of the pressure regulating valve 1.

[0045] The seat body 31 may include a fixed seat 311 and a sub-seat 312, wherein the fixed seat 311 is fixed to the inner wall of the pressure relief port 205, and the sub-seat 312 is connected and fixed to the fixed seat 311 by means of threaded connection or the like. The fixed seat 311 and the sub-seat 312 can cooperate with each other to form a pressure relief channel T. The elastic structure 32 includes a spring 321 and a support 322, wherein one end of the spring 321 abuts against the inner wall of the pressure relief channel T, and the other end abuts against the support 322, and the support 322 is used to support the blocking member 33.

[0046] Exemplarily, the fixing seat 311 is a body of revolution structure, which is a structure obtained by rotating a two-dimensional figure along one side of the figure. Figure 4a The schematic diagram of the fixing seat 311 viewed along the axial direction and Figure 4bThe cross-sectional schematic diagram along the radial direction is shown. The fixed seat 311 has a first opening groove 3111 and a connecting hole 3112. When the fixed seat 311 is installed on the pressure relief port 205, the opening of the first opening groove 3111 is away from the oil guide cavity 204, and the connecting hole 3112 connects the groove bottom of the first opening groove 3111 and the outer wall of the fixed seat 311 facing the oil guide cavity 204. The end of the connecting hole 3112 connected to the oil guide cavity 204 can be considered as the pressure relief channel T for connecting the port t of the oil guide cavity 204. The sub-seat 312 is used to be fixed to the first opening groove 3111, and a threaded groove can be set on the inner wall of the first opening groove 3111 to facilitate the threaded connection between the sub-seat 312 and the fixed seat 311.

[0047] The inner diameter of the first opening groove 3111 is larger than the outer diameter of the blocking member 33, and can be used to accommodate the blocking member 33. The inner diameter of the communication hole 3112 is smaller than the outer diameter of the blocking member 33, so that the blocking member 33 can be blocked by the communication hole 3112. When the blocking member 33 abuts against one end of the communication hole 3112 facing the first opening groove 3111, the blocking member 33 can block the communication hole 3112, thereby blocking the pressure relief channel T.

[0048] The cross section of the first opening slot 3111 is circular, and the cross section of the connecting hole 3112 is also circular, and the two are distributed in concentric circles along the axial direction of the fixing seat 311. The inner wall radius of the first opening slot 3111 is r1, and the inner wall radius of the connecting hole 3112 is r2, and r1 is greater than r3.

[0049] In one embodiment, the fixing seat 311 further includes a transition section 3113 connected between the first opening groove 3111 and the connecting hole 3112. The cross section of the transition section 3113 is also circular, and the inner wall radius of the transition section 3113 is r2, which is greater than r1 and less than r3, so that a stepped structure is formed between the first opening groove 3111, the transition section 3113, and the connecting hole 3112, which is convenient for cooperation with the blocking member 33.

[0050] Exemplarily, the sub-base 312 is also a rotating body structure. Figure 5a The schematic diagram of the sub-base 312 viewed along the axial direction is shown as follows: Figure 5b The sub-seat 312 has a second opening groove 3121 and a conducting hole 3122, and the conducting hole 3122 is used to connect the second opening groove 3121 with the outer wall of the valve body 2. When the sub-seat 312 is fixed to the first opening groove 3111 of the fixing seat 311, the second opening groove 3121 is connected with the first opening groove 3111 to form a space for accommodating the elastic structure 32 and the blocking member 33.

[0051] The cross section of the second opening groove 3121 is circular, and the cross section of the conducting hole 3122 is also circular, and the two are distributed in concentric circles along the axial direction of the sub-base 312. The inner wall radius of the second opening groove 3121 is r4, and the inner wall radius of the conducting hole 3122 is r5, and r4 is greater than r5. A first abutment surface J1 can be formed between the second opening groove 3121 and the conducting hole 3122, and the first abutment surface J1 is a part of the pressure relief channel T, and can be used for abutment of one end of the spring 321.

[0052] In one embodiment, the outer wall of the sub-base 312 is further formed with a pair of symmetrical notches q, which are opposite to each other along the radial direction of the sub-base 312 and form two clamping surfaces parallel to the axial direction of the sub-base 312. The two clamping surfaces can be clamped by a tool to apply force to the sub-base 312, so that the sub-base 312 can be rotated and removed from the fixed base 311.

[0053] In one embodiment, the support 322 is a rotating structural member. Figure 6a The schematic diagram of the support 322 viewed along the axial direction and Figure 6b The support 322 includes a base 3221 and a connecting portion 3222, wherein the base 3221 is used to support the blocking member 33, and the connecting portion 3222 protrudes from the base 3221 in the axial direction of the support 322 in a direction away from the blocking member 33, and the connecting portion 3222 is used to be embedded in the coil of the spring 321 to increase the connection reliability between the spring 321 and the support 322.

[0054] The cross sections of the base 3221 and the connecting portion 3222 are both circular, and the two are distributed in concentric circles along the axial direction of the support 322. The outer wall radius of the base 3221 is r6, and the outer wall radius of the connecting portion 3222 is r7, and r6 is greater than r7. A second abutment surface J2 can be formed between the base 3221 and the connecting portion 3222, and the second abutment surface J2 is also a part of the pressure relief channel T, and can be used for abutment of the other end of the spring 321.

[0055] In one embodiment, a concave bearing surface M is formed on one side of the base 3221 away from the connecting portion 3222, and the bearing surface M can be used to partially accommodate the blocking member 33, increase the contact area between the blocking member 33 and the base 3221, and improve the connection reliability between the two. Exemplarily, the blocking member 33 is a sphere, and the bearing surface M can include a truncated cone-shaped groove, similar to a trumpet shape.

[0056] Combined with the above Figures 3 to 6bAs shown, when the fixing seat 311 cooperates with the sub-seat 312, the first opening slot 3111 of the fixing seat 311 is connected with the second opening slot 3121 of the sub-seat 312 to form a space, one end of the spring 321 abuts against the first abutting surface J1 in the sub-seat 312, and the other end of the spring 321 abuts against the second abutting surface J2 on the support 322. The spring 321 can be partially accommodated in the second opening slot 3121 of the sub-seat 312, and the second opening slot 3121 can provide a certain guiding function for the expansion and contraction of the spring 321.

[0057] In some embodiments, in order to improve the sealing between the pressure relief component 3 and the valve body 2, a sealing ring 34 is provided between the pressure relief component 3 and the pressure relief port 205 of the valve body 2. The sealing ring 34 is provided around the sub-seat 312 and connected to the valve body 2. One end surface of the sealing ring 34 is in close contact with the fixed seat 311.

[0058] When the pressure regulating valve 1 is normal, Figure 3 As shown, the spring 321 has a certain elastic potential to push the support 322 to press the blocking member 33 against the port t of the pressure relief channel T, and the pressure relief channel T is isolated from the oil guide chamber 204. Figure 7 As shown, the hydraulic oil pressure in the oil guide chamber 204 increases, and the hydraulic oil enters from the port t to push the blocking member 33 to move to the left, and the blocking member 33 pushes the support 322 to move to the left, and the spring 321 is further compressed. The blocking member 33 moves to the left and leaves the fixed seat 311, and a gap is formed between the blocking member 33 and the inner wall of the fixed seat 311, which allows the hydraulic oil to enter the pressure relief channel T and exit the valve body 2 through the pressure relief channel T, thereby achieving the effect of pressure relief. When the pressure relief assembly 3 needs to be repaired or other operations are required, the sub-seat 312 can be removed from the fixed seat 311. When the oil pressure in the oil guide chamber 204 returns to normal, and the restoring force of the spring 321 is greater than the compression force applied to the spring 321 by the blocking member 33, a part of the elastic potential energy of the spring 321 is released to push the support 322 to press the blocking member 33 again at the port t of the pressure relief channel T, thereby isolating the pressure relief channel T from the oil guide chamber 204.

[0059] In summary, the speed change valve assembly 10 provided in the embodiment of the present application can timely release the pressure of the oil guide chamber 204 when the oil pressure in the oil guide chamber 204 increases due to the stuck pressure regulating valve 1 by setting the pressure relief assembly 3, so as to prevent the oil pressure in the oil guide chamber 204 and the oil pressure at the oil inlet 202 from being too high, reduce the risk of bursting the oil filter 20 upstream of the speed change valve assembly 10, and improve the safety of the system. The detachable structure of the pressure relief assembly 3 is simple in structure and easy to install, and can also reduce the cost of use and maintenance.

[0060] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A speed change valve assembly, characterized in that: include: Valve body, pressure regulating valve and pressure relief assembly; The valve body comprises a valve cavity, an oil inlet, an oil outlet, an oil guide cavity and a pressure relief port, and the inner wall of the valve cavity is formed with a first annular groove, a second annular groove and a pressure groove, the first annular groove is communicated with the oil inlet and the inlet of the oil guide cavity, the pressure groove is communicated with the outlet of the oil guide cavity, the second annular groove is communicated with the oil outlet, and the pressure relief port is communicated with the oil guide cavity; The pressure regulating valve is movably disposed in the valve cavity, and is used to move under the oil pressure of the hydraulic oil in the pressure groove to connect the first annular groove and the second annular groove; The pressure relief assembly includes a seat body, an elastic structure and a sealing member, the seat body is fixed at the pressure relief port, the seat body includes a pressure relief channel connecting the oil guide chamber and the outer surface of the valve body, the sealing member can be movably accommodated in the pressure relief channel, the elastic structure is arranged between the sealing member and the inner wall of the pressure relief channel, and the elastic structure is used to drive the sealing member to press and cover the port of the pressure relief channel for connecting the oil guide chamber.

2. The speed change valve assembly according to claim 1, characterized in that: The seat body includes a fixed seat and a sub-seat; The fixing seat is fixed to the inner wall of the pressure relief port, and the fixing seat has a first opening groove and a connecting hole, wherein the opening of the first opening groove faces away from the oil guide cavity, and the connecting hole connects the bottom of the first opening groove and the outer wall of the fixing seat facing the oil guide cavity; The sub-seat is fixed in the first opening groove, and the sub-seat has a second opening groove and a conducting hole. The second opening groove is connected with the first opening groove to form a space for accommodating the elastic structure. The conducting hole is used to connect the second opening groove with the outer wall of the valve body. The inner diameter of the conducting hole is smaller than the inner diameter of the second opening groove. A first abutting surface for abutting against the elastic structure is formed between the conducting hole and the second opening groove.

3. The speed change valve assembly according to claim 2, characterized in that: The sub-base is connected to the fixing base via threads.

4. The speed change valve assembly according to claim 2, characterized in that: The inner diameter of the communicating hole is smaller than the outer diameter of the blocking piece, and the inner diameter of the first opening groove is larger than the outer diameter of the blocking piece.

5. The speed change valve assembly according to claim 3, characterized in that: The fixing seat also has a transition section connected between the first opening groove and the connecting hole, and the inner wall radius of the transition section is smaller than the inner wall radius of the first opening groove and larger than the inner wall radius of the connecting hole.

6. The speed change valve assembly according to claim 1, characterized in that: The elastic structure includes a spring and a support, one end of the spring abuts against the inner wall of the pressure relief channel, and the other end abuts against the support, and the support is used to support the blocking member.

7. The speed change valve assembly according to claim 6, characterized in that: The support comprises a base and a connecting portion, wherein the connecting portion protrudes from the base and is used to be embedded in the coil of the spring, and a second abutting surface for abutting against the spring is formed between the connecting portion and the base.

8. The speed change valve assembly according to claim 7, characterized in that: A concave bearing surface is formed on one side of the base away from the connecting portion, and the bearing surface is used to partially accommodate the blocking member.

9. The speed change valve assembly according to any one of claims 1 to 8, characterized in that: The speed change valve assembly further includes a sealing ring, which surrounds the pressure relief passage and is disposed between the valve body and the pressure relief component.

10. An engineering machine, characterized in that: A hydraulic speed change system comprising a hydraulic pump, an oil filter and a speed change valve assembly according to any one of claims 1 to 9; The oil filter is connected between the hydraulic pump and the oil inlet of the speed change valve assembly.

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