A split type automatic stroke unloading valve

Abstract

The present invention discloses a split-type automatic stroke unloading valve, comprising a rack piston with an unloading hole, wherein an unloading assembly is arranged in the unloading hole, and the unloading assembly comprises a pair of stroke valve seats and a pair of stroke valve stems; blind holes are arranged on opposite end surfaces of the two stroke valve stems; a limit rod, both ends of the limit rod are respectively inserted into the blind holes, and the two blind holes form a limit cavity for accommodating the limit rod, and the length of the limit cavity is greater than the length of the limit rod so that the limit rod can move axially along the limit cavity; and an abutment spring, which is sleeved on the limit rod and the two ends of the abutment spring are respectively abutted against the stopper of the stroke valve stem, and the abutment spring allows the moving part to partially pass through the axial hole; the limit rod is inserted into the blind hole of the stroke valve stem for guiding, and the stroke valve stems at both ends have a radial limiting effect on the limit rod, which can reduce the disturbance of the hydraulic oil on the limit rod during the unloading process of the automatic stroke unloading valve.

Description

Technical Field

[0001] The invention relates to the field of power steering devices, in particular to a split type automatic travel unloading valve. Background Art

[0002] Currently, the common split-type automatic stroke unloading valve is composed of a stroke valve stem, a stroke valve seat, a limit rod, an abutment spring, a sliding sleeve and an adjusting bolt, etc. The sealing and pressure-maintaining functions are achieved through the cooperation of the stroke valve stem and the stroke valve seat.

[0003] However, after long-term use, the current split-type automatic stroke unloading valve has been found to have the following problems:

[0004] 1. The limit rod in the middle is shorter and has no radial limit. When the high-pressure oil (hydraulic oil) flows through the working chamber (unloading hole) of the unloading valve, it causes radial disturbance to the limit rod, causing the stroke valve stem to be offset from the stroke valve seat when it is opened.

[0005] 2. When unloading the steering gear, the ideal effective throttling shape is a circular throttling port composed of a travel valve stem and a travel valve seat (the contact surface between the traditional travel valve stem and the travel valve seat is a conical surface contact (see Figure 1 ), when the conical surfaces separate from each other, a throttle port will be formed), under the disturbance of the limit rod, the stroke valve stem and the stroke valve seat are not coaxial, which will change the ideal annular throttle port diameter, so the residual pressure during unloading is unstable.

[0006] 3. Due to the disturbance of the limit rod, the seal between the stroke valve stem and the stroke valve seat is not an ideal line seal, resulting in poor sealing between the stroke valve stem and the stroke valve seat. Summary of the invention

[0007] In view of the above problems, the present invention proposes a new technical solution. By redesigning the structure of the unloading assembly, the limit rod therein can be stably connected with the stroke valve stem, avoiding the limit rod offset due to high-pressure oil disturbance, which would cause the stroke valve stem and the stroke valve seat to be out of coaxiality.

[0008] The specific scheme proposed by the present invention is as follows:

[0009] A split type automatic stroke unloading valve comprises a rack piston with an unloading hole, wherein an unloading assembly is arranged in the unloading hole, and the unloading assembly comprises

[0010] A pair of travel valve seats are respectively fixed on the left and right sides of the unloading hole, and each of the travel valve seats is provided with an axial hole;

[0011] A pair of travel valve stems; corresponding to the travel valve seats one by one; each of the travel valve stems has a moving part and a stopper, the moving part is coaxially arranged with the shaft hole and is clearance-matched with the travel valve seat through the shaft hole; the stopper has a diameter greater than the shaft hole diameter and the stopper parts of the two travel valve stems are arranged opposite to each other, and blind holes are arranged on the opposite end surfaces of the two stopper parts;

[0012] A limit rod is located between the two stopper portions; both ends of the limit rod are respectively inserted into the blind holes, and the two blind holes form a limit cavity for accommodating the limit rod, and the length of the limit cavity is greater than the length of the limit rod so that the limit rod can move axially along the limit cavity; and

[0013] An abutment spring is sleeved on the limit rod and both ends of the abutment spring are respectively abutted against the stopper of the travel valve rod, and the abutment spring enables the moving part to partially pass through the shaft hole.

[0014] Furthermore, a concave concave cavity is provided in the end surface opposite to the travel valve seat and the travel valve stem, and the height line of the conical cavity is colinear with the axis of the shaft hole; the connection between the moving part and the stop part is a spherical structure; under the action of the abutment spring, the spherical structure and the conical cavity are sealed and cooperated so that the middle section of the shaft hole and the unloading hole are not connected.

[0015] Furthermore, the axial hole includes a piston hole and mounting holes arranged on both sides of the piston hole and having a diameter larger than the piston hole. The travel valve seat is fixed in the mounting hole by threaded engagement, and the travel valve stem, limit rod and abutment spring are all located in the piston hole.

[0016] Furthermore, the split-type automatic stroke unloading valve also includes a push assembly corresponding to the stroke valve stem one by one, and the push assembly is located outside the shaft hole; the left and right movement of the rack piston causes the stroke valve stem to push and abut against the corresponding push assembly respectively.

[0017] Furthermore, the push assembly includes an adjusting bolt and a sliding sleeve at least partially sleeved on the adjusting bolt, the sliding sleeve is interference fit with the adjusting bolt, and the sliding sleeve is directly opposite to the travel valve stem.

[0018] Furthermore, the split-type automatic stroke unloading valve also includes a valve body assembly and a shell assembly, the valve body assembly and the shell assembly are fixed to form a piston cavity, and the rack piston is arranged in the piston cavity; the push assembly is respectively fixed to the valve body assembly and the shell assembly.

[0019] The beneficial effects achieved by adopting this technical solution are:

[0020] This solution designs a split-type automatic stroke unloading valve with a new structure. Without changing other components, only the structure of the stroke valve stem and the limit rod needs to be changed to solve the problem of limit rod offset disturbance.

[0021] (1) The limit rod is inserted into the blind hole of the travel valve stem for guidance, and the travel valve stems at both ends have a radial limiting effect on the limit rod, which can reduce the disturbance of the hydraulic oil on the limit rod during the unloading process of the automatic travel unloading valve, so that the throttle shape of the travel valve stem and the travel valve seat maintains an ideal annular throttle shape.

[0022] (2) The spherical stroke valve stem (i.e., the connection between the moving part and the stopper part is a spherical structure) is used. The contact between the spherical surface of the stroke valve stem and the conical surface of the stroke valve seat plays a sealing role, which improves the sealing effect of the two contact surfaces and can actually reduce the problem of large leakage in the steering gear. And by using professional testing instruments to test the pressure holding capacity of the spherical stroke valve stem and the conical stroke valve stem, it can be well found that the pressure holding capacity of the spherical stroke valve stem is much higher than that of the conical stroke valve stem. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a structural diagram in which the contact surfaces of the stroke valve stem and the stroke valve seat in the prior art are both conical surfaces.

[0024] Figure 2 This is a partial structural diagram of the split-type automatic stroke unloading valve of this scheme.

[0025] Figure 3 It is an exploded structural diagram between the travel valve seat, travel valve stem, limit rod and abutment spring.

[0026] Figure 4 It is a combined structural diagram of a travel valve seat, a travel valve stem, a limit rod and an abutment spring.

[0027] Figure 5 This is the structural diagram of the formation state of the throttle.

[0028] Figure 6 This is a diagram of the matching structure between the travel valve stem and the travel valve seat after the travel valve stem is offset in different directions due to the disturbance of the limit rod.

[0029] Figure 7 The figure is the overall structure diagram of a split type automatic stroke unloading valve.

[0030] Among them: 10 stroke valve seat, 11 shaft hole, 12 conical concave cavity, 20 stroke valve stem, 21 moving part, 22 stopper part, 23 spherical structure, 30 limit rod, 40 abutment spring, 51 adjustment bolt, 52 sliding sleeve, 100 rack piston, 200 valve body assembly, 300 shell assembly. DETAILED DESCRIPTION

[0031] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0032] This embodiment provides a split-type automatic stroke unloading valve, and the pressure-maintaining capacity and sealing capacity of the unloading assembly are enhanced by further designing the structures of the limit rod and the stroke valve stem in the split-type automatic stroke unloading valve.

[0033] For details, see Figure 2-Figure 4 The split-type automatic stroke unloading valve comprises a rack piston 100 with an unloading hole, and an unloading assembly is arranged in the unloading hole, wherein the unloading assembly comprises a pair of stroke valve seats 10, the stroke valve seats 10 are respectively fixed on the left and right sides of the unloading hole, and each stroke valve seat 10 is provided with an axial hole 11; a pair of stroke valve stems 20; the stroke valve stems 20 correspond to the stroke valve seats 10 one by one; each stroke valve stem 20 has a moving part 21 and a stopper part 22, the moving part 21 is coaxially arranged with the axial hole 11 and passes through the axial hole 11 1 is in clearance fit with the stroke valve seat 10; the diameter of the stopper 22 is larger than the diameter of the shaft hole 11 and the stopper 22 of the two stroke valve stems 20 is arranged opposite to each other, and blind holes are arranged on the opposite end surfaces of the two stopper 22; the limiting rod 30 is located between the two stopper 22 and the two ends of the limiting rod 30 are respectively inserted into the blind holes; it can be understood that the two blind holes form a limiting cavity for accommodating the limiting rod 30, and the overall length of the limiting cavity is larger than the length of the limiting rod 30 so that the limiting rod 30 can move axially along the limiting cavity.

[0034] It should be noted that the limit rod 30 and the blind holes on the two end stroke valve stem 20 are matched with a small clearance, and the two ends of the limit rod 30 are always kept in the blind holes, so that the stroke valve stem 20 and the limit rod 30 can move relatively along the axis; by limiting the two ends of the limit rod 30 in the blind holes, the possibility of radial rotation of the limit rod 30 is limited; therefore, the disturbance of the hydraulic oil to the limit rod 30 during unloading can be greatly reduced.

[0035] An abutting spring 40 is sleeved on the limiting rod 30 , and both ends of the abutting spring 40 abut against the stopper 22 of the travel valve rod 20 respectively, so that the abutting spring 40 allows the moving part 21 to partially pass through the shaft hole 11 .

[0036] It can be understood that, see Figure 1 , Figure 4-Figure 5A limit rod 30 and an abutting spring 40 are arranged between the two stroke valve stems 20. The two ends of the limit rod 30 are inserted into the blind hole. The two ends of the abutting spring 40 abut on the stroke valve stem 20 to give the stroke valve stem 20 elastic support to the left and right. The moving part 21 of the stroke valve stem 20 extends out of the shaft hole 11 under the action of the elastic force, so that the stroke valve stem 20 and the stroke valve seat 10 are in a sealed and pressure-maintaining state; when the moving part 21 of the stroke valve stem 20 is subjected to the action of external force, it will make a retreating movement to compress the abutting spring 40 until the end face of the moving part 21 of the stroke valve stem 20 is flush with the end face of the stroke valve seat 10; at this time, the stopper 22 retreats so that the stroke valve stem 20 and the stroke valve seat 10 release the sealed and pressure-maintaining state, and an annular throttle is formed between the stroke valve stem 20 and the stroke valve seat 10, and the external hydraulic oil enters the middle section of the unloading hole through the shaft hole 11 and the annular throttle in turn.

[0037] In this embodiment, see Figure 2 In order to ensure that the annular throttle formed between the travel valve stem 20 and the travel valve seat 10 maintains an ideal shape, a concave concave cavity 12 is provided in the end surface opposite to the travel valve seat 10 and the travel valve stem 20, wherein the height line of the conical cavity 12 is colinear with the axis of the shaft hole 11; the connection between the moving part 21 and the stop part 22 on the travel valve stem 20 is a spherical structure 23; in this way, under the action of the abutment spring 40, the spherical structure 23 and the conical cavity 12 are sealed and matched so that the middle section of the shaft hole 11 and the unloading hole are not connected.

[0038] The contact surfaces of the conventional travel valve stem 20 and the travel valve seat 10 are both conical surfaces. Figure 1 When the conical surfaces are separated from each other, a throttle will be formed. However, as long as the limit rod 30 is disturbed, the throttle will not be in an ideal state. Therefore, the traditional conical surface and conical surface matching method is changed to the existing arc surface and conical surface matching method. In this way, the stroke valve stem with a spherical structure can be turned even when the stroke valve stem rotates at a small angle ( Figure 6 When the valve stem rotates clockwise or counterclockwise, the spherical structure 23 is still in sealing cooperation with the conical cavity 12 (see FIG). Relying on the spherical structure, the original line-surface seal is not changed, thus improving the original poor sealing problem.

[0039] In this embodiment, see Figure 2 The unloading hole includes a piston hole and mounting holes arranged on both sides of the piston hole and having a diameter larger than the piston hole. The travel valve seat 10 is fixed in the mounting hole by threaded engagement. The travel valve stem 20, the limit rod 30 and the abutment spring 40 are all located in the piston hole.

[0040] In this embodiment, the split-type automatic stroke unloading valve also includes a push assembly corresponding to the stroke valve stem 20, and the push assembly is located outside the shaft hole 11; the left and right movement of the rack piston 100 causes the stroke valve stem 20 to push and abut against the corresponding push assembly respectively.

[0041] It can be understood that, under the pushing action of the pushing assembly, the travel valve stem 20 will produce a retreating movement, so that the unloading hole is connected, thereby ensuring the unloading operation of the hydraulic oil.

[0042] In this embodiment, the push assembly includes an adjusting bolt 51 and a sliding sleeve 52 at least partially sleeved on the adjusting bolt 51 . The sliding sleeve 52 is interference fit with the adjusting bolt 51 , and the sliding sleeve 52 is directly opposite to the travel valve stem 20 .

[0043] In this embodiment, see Figure 7 The split-type automatic stroke unloading valve also includes a valve body assembly 200 and a housing assembly 300. The valve body assembly 200 and the housing assembly 300 are fixed to form a piston cavity, and the rack piston 100 is arranged in the piston cavity; the push assembly is fixed on the valve body assembly 200 and the housing assembly 300 respectively.

[0044] For the split type automatic stroke unloading valve with the above structure, the assembly process can be summarized into the following steps:

[0045] When assembling the split-type automatic stroke unloading valve, the rack piston 100 is used as a carrier, and the assembly can be started from any end of the rack piston 100: taking the assembly from the right end of the rack piston 100 as an example, first install the right end stroke valve seat 10 on the rack piston 100, and then install the right stroke valve stem 20, and insert the limit rod 30 into the blind hole of the right stroke valve stem 20; the limit rod 30 and the blind hole of the right stroke valve stem 20 are matched with a small gap, which is used for the stroke valve stem and the limit rod to move on the same axis; then put the abutment spring 40 on the limit rod 30, and then put the blind hole end of the left stroke valve stem 20 on the limit rod 30, and finally screw in the left stroke valve seat 10, and the entire split-type automatic stroke unloading valve is assembled.

[0046] This technical solution can solve the problem of limit rod offset disturbance without changing other components, only by changing the structure of the travel valve stem and the limit rod.

[0047] For sealing function:

[0048] The traditional split type automatic stroke unloading valve mainly relies on the cooperation between the stroke valve seat cone and the stroke valve stem cone for sealing, see Figure 1At the same time, in order to ensure the reliability of the seal, the conical surfaces of the travel valve seat and the travel valve stem are usually designed with different conical angles, and the two conical angles form a linear seal; under the action of the abutment spring, the conical surface of the travel valve stem is pressed against the conical surface of the travel valve seat, and the sealing effect is the cooperation of the two conical surfaces; however, in actual work, it is inevitable that the limit rod 30 is disturbed by the hydraulic oil, and the disturbance of the limit rod 30 will cause the travel valve stem to be not coaxial with the travel valve seat when in the open state or the closed state, which seriously affects the sealing performance. Therefore, this scheme increases the length of the limit rod 30 and opens a blind hole at the tail end of the travel valve stem, and reduces the degree of disturbance deviation of the limit rod 30 through the cooperation between the limit rod 30 and the blind hole.

[0049] For the hold pressure function:

[0050] When the travel valve stem touches the sliding sleeve of the adjusting bolt assembly, the travel valve stem is pushed open, so that a throttle is formed between the travel valve stem and the travel valve seat. Figure 5 , Figure 7 , the high-pressure oil (hydraulic oil) is unloaded through the annular throttle port between the stroke valve stem and the stroke valve seat. This throttle port also throttles the high-pressure oil when unloading. After demonstration, the residual pressure of the steering gear when unloading is related to the effective throttling area of ​​the annular throttle port. Generally, the residual pressure after unloading can be accurately controlled by changing the diameter of the stroke valve stem; according to the requirements of the whole vehicle, it is generally required that the steering gear still has a residual pressure of 4.5 to 7 MPa when unloading; but if the stroke valve stem and the stroke valve seat are not coaxial due to the disturbance offset of the limit rod 30, the effective throttling area of ​​the ideal annular throttle port will also be changed, so the residual pressure holding pressure during unloading is unstable; therefore, this scheme further changes the traditional cone-cone matching method of the stroke valve seat and the stroke valve stem; adopts a more effective spherical surface and cone matching method, that is, the original cone structure of the stroke valve stem is modified into a spherical structure, which can solve the problem of pressure difference caused by slight offset of the stroke valve stem.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A split type automatic stroke unloading valve, comprising a rack piston (100) having an unloading hole, wherein an unloading assembly is arranged in the unloading hole, characterized in that: The unloading assembly comprises a pair of travel valve seats (10) respectively fixed on the left and right sides of the unloading hole, each of the travel valve seats (10) being provided with an axial hole (11); a pair of travel valve stems (20) corresponding to the travel valve seats (10) one by one; each of the travel valve stems (20) having a moving portion (21) and a stopper portion (22), the moving portion (21) being coaxially arranged with the axial hole (11) and being clearance-matched with the travel valve seat (10) through the axial hole (11); the stopper portion (22) having a diameter greater than The diameter of the shaft hole (11) and the stoppers (22) of the two travel valve stems (20) are arranged opposite to each other, and blind holes are arranged on the opposite end surfaces of the two stoppers (22); a limit rod (30) is located between the two stoppers (22); the two ends of the limit rod (30) are respectively inserted into the blind holes, and the two blind holes form a limit cavity for accommodating the limit rod (30), and the length of the limit cavity is greater than the length of the limit rod (30) so that the limit rod (30) can move axially along the limit cavity, and keep the two ends of the limit rod (30) always located in the blind hole; and an abutment spring (40) is sleeved on the limit rod (30) and the two ends of the abutment spring (40) are respectively abutted against the stoppers (22) of the travel valve stem (20), and the abutment spring (40) allows the movable portion (21) to partially pass through the shaft hole (11); the travel valve seat (10) An inwardly concave concave cavity (12) is provided in the end surface opposite to the travel valve stem (20), and the height line of the concave concave cavity (12) is colinear with the axis of the shaft hole (11); the connection between the moving part (21) and the stop part (22) is a spherical structure (23); under the action of the abutment spring (40), the spherical structure (23) and the conical concave cavity (12) are sealed and matched so that the shaft hole (11) and the middle section of the unloading hole are not connected; the unloading hole includes a piston hole and a piston arranged in the piston hole. The travel valve seat (10) is fixed in the mounting hole by screwing on both sides and has a diameter larger than that of the piston hole. The travel valve stem (20), the limit rod (30) and the abutment spring (40) are all located in the piston hole. The split-type automatic travel unloading valve also includes a push assembly corresponding to the travel valve stem (20) one by one, and the push assembly is located outside the shaft hole (11). The left and right movement of the rack piston (100) causes the travel valve stem (20) to push and abut against the corresponding push assembly.

2. A split type automatic stroke unloading valve according to claim 1, characterized in that: The push assembly comprises an adjusting bolt (51) and a sliding sleeve (52) at least partially sleeved on the adjusting bolt (51); the sliding sleeve (52) is interference fit with the adjusting bolt (51); and the sliding sleeve (52) is directly opposite to the travel valve stem (20).

3. A split type automatic stroke unloading valve according to claim 2, characterized in that: The split-type automatic stroke unloading valve also includes a valve body assembly (200) and a housing assembly (300); the valve body assembly (200) and the housing assembly (300) are fixed to form a piston cavity, and the rack piston (100) is arranged in the piston cavity; the push assembly is respectively fixed to the valve body assembly (200) and the housing assembly (300).

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