Control valve with feedback mechanism

Abstract

The control valve comprises a valve shell and a valve element arranged in the valve shell in an axial moving mode, a groove hole transversely penetrating through the valve element is formed in the axial middle of the valve element, and a valve pin penetrates through the groove hole in the longitudinal direction; and a feedback mechanism. The adjusting shaft is supported by the valve shell and extends in the longitudinal direction, and the adjusting shaft is provided with an eccentric shaft section; the shifting fork comprises a body and a pair of fork arms transversely extending out of the body, a shifting fork through hole longitudinally penetrating through the body is formed in the body, the fork arms are inserted into the slotted holes, and the valve pin is inserted between the pair of fork arms; the feedback rod comprises a rod portion extending transversely, a first end of the rod portion forms a connecting portion, a second end of the rod portion forms a pair of protruding pieces facing each other in the longitudinal direction, a body of the shifting fork is inserted between the pair of protruding pieces, and protruding piece through holes penetrating in the longitudinal direction are formed in the protruding pieces respectively. Each protruding piece is connected with the body of the shifting fork through a corresponding pre-tightened torsion spring. The eccentric shaft section penetrates through the shifting fork through hole, the protruding piece through hole and the torsional spring.

Description

TECHNICAL FIELD

[0001] The present application relates to a control valve with a feedback mechanism capable of providing force feedback to a valve spool. BACKGROUND

[0002] Some hydraulic control valves contain a feedback mechanism to provide force feedback to a valve spool. For example, an electric proportional control valve for regulating the displacement of a hydraulic pump adjusts the swash plate angle of the pump by supplying control hydraulic pressure to a displacement regulating mechanism to drive the displacement regulating mechanism, while the displacement regulating mechanism reacts on the valve spool through a feedback lever of the electric proportional control valve to balance the position of the valve spool. The outer end of the feedback lever is connected to the displacement regulating mechanism, and the inner side of the feedback lever is coupled to a feedback regulating jaw acted on by a tension spring. A valve pin mounted on the valve spool is inserted between the two arms of the feedback regulating jaw. When the electromagnet of a certain control end of the electric proportional control valve is energized, the electromagnet plunger pushes the valve spool to open an oil passage to supply hydraulic pressure to the displacement regulating mechanism to change the pump displacement. At the same time, the displacement regulating mechanism stretches the spring through the feedback lever acting on the arms of the feedback regulating jaw, and provides force feedback to the valve spool through the feedback regulating jaw and the valve pin. This feedback mechanism comprising the feedback lever and the feedback regulating jaw contains complex parts, many machining surfaces, complex machining processes, complex assembly processes, and high precision requirements (especially the machining and assembly precision related to the feedback regulating jaw), resulting in high cost. Therefore, it is desirable to improve the feedback mechanism for a control valve. SUMMARY

[0003] The purpose of the present application is to provide a control valve with a feedback mechanism capable of providing bidirectional force feedback to a valve pin with a simple structure.

[0004] To this end, the present application provides, in one aspect thereof, a control valve comprising:

[0005] a valve housing and a valve spool axially movably arranged in the valve housing, an axially middle part of the valve spool being provided with a slot hole transversely passing through the valve spool, and a valve pin longitudinally passing through the slot hole; and

[0006] a feedback mechanism, the feedback mechanism comprising:

[0007] a regulating shaft supported by the valve housing and extending longitudinally, the regulating shaft having an eccentric shaft section;

[0008] a yoke comprising a body and a pair of yoke arms transversely extending from the body, a yoke through hole longitudinally passing through the body being formed, the pair of yoke arms being inserted into the slot hole, and the valve pin being inserted between the pair of yoke arms;

[0009] a feedback lever comprising a laterally extending lever portion, a first end of the lever portion forming a connecting portion, a second end of the lever portion forming a pair of tabs longitudinally facing each other, the body of the fork being inserted between the pair of tabs, a tab through hole longitudinally passing through each of the pair of tabs, wherein each tab is connected to the body of the fork by a corresponding pre-tightened torsion spring;

[0010] wherein the eccentric shaft segment passes through the fork through hole, the tab through hole and the torsion spring.

[0011] The connecting portion of the feedback lever is configured to be connected to a displacement adjusting mechanism of a hydraulic pump or a hydraulic motor. The valve housing has a single mating surface configured to be connected to a housing of the hydraulic pump or the hydraulic motor, and all oil ports of the control valve can be formed on the mating surface.

[0012] The control valve according to the present application, the feedback mechanism of which comprises a combination of a feedback lever, a fork and a pair of torsion springs, has simple part form, easy to process, less material usage, less processing procedures and simple assembly process. These factors comprehensively lead to the cost reduction of the feedback mechanism. BRIEF DESCRIPTION OF DRAWINGS

[0013] The foregoing and other aspects of the present application will become more fully understood and appreciated by reference to the following detailed description, taken in conjunction with the accompanying drawings, in which:

[0014] Figure 1 is a schematic diagram of an application scenario of the control valve of the present application;

[0015] Figure 2 is a perspective view of a spool and a feedback mechanism of the control valve of the present application;

[0016] Figure 3 is a perspective view of a spool of the control valve of the present application;

[0017] Figure 4 is a perspective view of a part of the feedback mechanism of the control valve of the present application;

[0018] Figures 5-9 are perspective views of a feedback lever, a fork, an upper torsion spring, a lower torsion spring and an adjusting shaft in the feedback mechanism, respectively;

[0019] Figure 10 is a perspective view of the control valve of the present application;

[0020] Figure 11 、 Figure 12 are partial front and top view schematic diagrams showing the interaction between the spool and the feedback mechanism, respectively. DETAILED DESCRIPTION

[0021] The present invention relates generally to a control valve with a feedback mechanism. The feedback mechanism is used to provide force feedback to the motion of the spool so that the spool is maintained in a more stable equilibrium position.

[0022] One specific example of a control valve of the present invention is an electric proportional valve. One exemplary application scenario for the electric proportional valve is for controlling the displacement of a pump, as shown in Figure 1

[0023] Referring to Figure 1 , a hydraulic pump P is integrated in a pump housing Pb. The shown hydraulic pump P is a bi-directional pump for forming a closed hydraulic system through oil lines on both sides. The hydraulic pump P has a variable displacement, which is adjusted by a displacement adjusting mechanism C. The displacement adjusting mechanism C is a piston type, comprising a piston C1 arranged in a cylinder and piston rods C2, C3 extending from the piston C1 in opposite directions. The piston C1 separates two piston chambers in the cylinder. The piston rod C2 is connected to a feedback rod R (as described later) and the piston rod C3 is connected to a variable displacement element of the hydraulic pump P, such as a swash plate.

[0024] The position of the piston C1 in the displacement adjusting mechanism C depends on the hydraulic pressure in the two piston chambers. The hydraulic pressure in the two piston chambers is supplied by a control valve V1 (electric proportional valve). The valve housing Vb of the control valve V1 is assembled on the pump housing Pb. In addition to containing the hydraulic pump P, the pump housing Pb can also integrate elements related to the hydraulic pump P, such as the shown displacement adjusting mechanism C, relief valves V2, V3, other related hydraulic valves (not shown), etc.

[0025] The inlets of the relief valves V2, V3 are connected to the main oil lines on both sides of the hydraulic pump P, and the outlets of the relief valves V2, V3 are connected to a relief oil line. A control oil line L is connected to the relief oil line. The oil pressure in the control oil line L is taken from the oil pressure generated by the relief of one of the main oil lines on both sides of the hydraulic pump P.

[0026] The control valve V1 is a three-position four-way valve, the valve position of which is controlled by electromagnets on both sides. The control valve V1 has P, A, B, T ports (not labeled in the figure, but known to those skilled in the art), wherein the P port is connected to the control oil line L, the T port is connected to the tank, and the A, B ports are respectively connected to the corresponding piston chambers of the displacement adjusting mechanism C.

[0027] ​When neither solenoid is energized, the control valve V1 is in the neutral valve position, in which the P, A, B, T ports of the control valve V1 are communicated through an internal throttling passage. When either solenoid is energized, the control valve V1 switches to one of the two working valve positions, in which the P port is communicated with one of the A, B ports and the T port is communicated with the other one of the A, B ports, thus supplying the control oil passage L to one of the two piston chambers and keeping the other one communicated with the tank, thereby forcing the piston C1 to move, which drives the piston rod C3 to move and drives the variable displacement element in the pump P to change the displacement of the pump P. At the same time, the piston C1 drives the piston rod C2 to move and drives the feedback lever R to move, thus providing a force feedback to the control valve V1 (as described later).

[0028] The feedback lever R is part of the feedback mechanism of the control valve V1. The feedback mechanism of the control valve V1 will be described below with reference to Figures 2-12 the accompanying drawings.

[0029] It should be noted that the present application is directed to the improvement of the feedback mechanism of the control valve V1, therefore only the feedback mechanism and the related spool structure are shown in the drawings, and other structures of the control valve V1 and the hydraulic pump P are well known in the art and thus not shown and described.

[0030] Firstly, refer to Figure 2 the feedback mechanism is configured to act on the spool 1 of the control valve V1. The spool 1 is axially movably arranged in the valve housing Vb. The feedback mechanism mainly comprises a yoke 2, an adjusting shaft 3, the feedback lever R, and a pair of torsion springs 20a, 20b.

[0031] For the convenience of description of the various components, some directions are defined with reference to Figure 2 the spool 1 extends in the axial direction, the feedback lever R extends in the transverse direction perpendicular to the axial direction of the spool 1, and the adjusting shaft 3 extends in the longitudinal direction perpendicular to the axial and transverse directions of the spool and the feedback lever R. Hereinafter, the axial, transverse and longitudinal directions are defined as above.

[0032] As shown in Figure 3 , the axial middle section of the spool 1 is modified to cooperate with the feedback mechanism. No peripheral oil groove (undercut groove) or internal oil hole for realizing the valve port communication function is arranged on the axial middle section of the spool 1. A long slot 11 is formed on the axial middle section of the spool 1. The slot 11 extends from the transverse front side to the transverse rear side of the spool 1 and extends along the axial direction of the spool 1 for a predetermined length. The slot 11 separates the axial middle section of the spool 1 into a top wall and a bottom wall which face each other and have equal thickness. A valve pin 12 is fixed at the axial center of the spool 1. The valve pin 12 extends in the longitudinal direction perpendicular to the axial and transverse directions of the spool 1. The upper and lower ends of the valve pin 12 are fixed in the top wall and the bottom wall of the spool 1 respectively, and the main body portion of the valve pin 12 is located in the slot 11.

[0033] As shown in Figure 5As shown, the feedback lever R comprises a laterally extending lever portion 13 as its main body, the first end of the lever portion 13 forms a connecting portion 14, for example a truncated spherical connecting portion as shown, for pivotably connecting with the piston rod C2. The second end of the lever portion 13 forms an upper tab 15a and a lower tab 15b longitudinally parallel facing each other. Longitudinally extending through holes 16a, 16b are formed in the upper and lower tabs 15a, 15b respectively. The through holes 16a, 16b are coaxial with each other and have equal diameters. In addition, a post 17a is mounted on the upper tab 15a at a position close to the lever portion 13, the post 17a extends upward from the upper surface of the upper tab 15a in the longitudinal direction. A post 17b is mounted on the lower tab 15b at a position close to the lever portion 13, the post 17b extends downward from the lower surface of the lower tab 15b in the longitudinal direction. The posts 17a, 17b are inserted into the insertion holes in the tabs 15a, 15b at their root portions, and the root portions are fixed to the tabs 15a, 15b by interference fit, of course other fixing means (for example threaded connection, welding, riveting, etc.) can also be used to fix the posts 17a, 17b to the tabs 15a, 15b. The exposed portions of the posts 17a, 17b are conical, that is, the diameters gradually decrease away from the tabs 15a, 15b. The portions of the posts 17a, 17b close to the tabs 15a, 15b form annular grooves respectively. The posts 17a, 17b extend in the longitudinal direction in opposite directions from each other, and can be substantially coaxial with each other in the longitudinal direction.

[0034] Referring to Figure 6 , the spool 2 comprises a substantially elongated body 21 extending axially along the spool. The longitudinal thickness of the body 21 is slightly smaller than the distance between the upper and lower tabs 15a, 15b of the feedback lever R, so that the body 21 can be freely inserted between the upper and lower tabs 15a, 15b.

[0035] A longitudinally through hole 22 is formed in the center of the body 21. The inner diameter of the through hole 22 is substantially equal to the inner diameters of the through holes 16a, 16b. On the longitudinally opposite sides of the body 21, convex rings 22a are formed around the opening of the through hole 22.

[0036] A pair of prongs 23a, 23b extending laterally from the body are formed on one lateral side of the body 21. The prongs 23a, 23b define a notch 24 therebetween. The width of the notch 24 in the axial direction is substantially equal to the outer diameter of the valve pin 12, so that the valve pin 12 can be inserted in the notch 24, and the spool 2 as a whole can swing around the valve pin 12. The total width occupied by the prongs 23a, 23b in the axial direction is arranged to be able to be inserted in the slot hole 11 with a certain margin, so that the prongs 23a, 23b will not touch the corresponding parts on the spool 1 in the entire range of axial movement of the valve pin 12 and swinging of the spool 2 around the valve pin 12. The thickness of the prongs 23a, 23b in the longitudinal direction can be equal to or slightly smaller than the longitudinal height of the slot hole 11.

[0037] The fixed pins 25a, 25b are respectively formed on the longitudinal side surfaces of the body 21 perpendicularly to the body 21, and the central axes of the fixed pins 25a, 25b are parallel. The central axes of the fixed pins 25a, 25b are arranged symmetrically with respect to the median plane of the fork 2 defined by the central axis of the through hole 22 and the transverse direction of the fork, and the fixed pins 25a, 25b point to longitudinally opposite directions.

[0038] The fixed pins 25a, 25b are respectively formed on the longitudinal side surfaces of the body 21 perpendicularly to the body 21, and the central axes of the fixed pins 25a, 25b are parallel. The central axes of the fixed pins 25a, 25b are arranged symmetrically with respect to the median plane of the fork 2 defined by the central axis of the through hole 22 and the transverse direction of the fork, and the fixed pins 25a, 25b point to longitudinally opposite directions.

[0039] Referring to Figure 7 , the pre-tightened torsion spring 20a is installed by the post 17a and the fixed pin 25a, wherein one end of the torsion spring 20a is annular and clamped in the annular groove on the post 17a, and the other end of the torsion spring 20a is rod-shaped and inserted into the insertion hole of the fixed pin 25a. In the state that the torsion spring 20a is installed on the post 17a and the fixed pin 25a, the torsion spring 20a bears a preset torsion force. Similarly, referring to Figure 8 , the pre-tightened torsion spring 20b is installed by the post 17b and the fixed pin 25b, wherein one end of the torsion spring 20b is annular and clamped in the annular groove on the post 17b, and the other end of the torsion spring 20b is rod-shaped and inserted into the insertion hole of the fixed pin 25b. In the state that the torsion spring 20b is installed on the post 17b and the fixed pin 25b, the torsion spring 20b bears a preset torsion force. The torsion force of the torsion spring 20b and the torsion force of the torsion spring 20a are respectively equal in magnitude and opposite in direction to the force generated on the feedback rod R.

[0040] The conical shape of the posts 17a, 17b facilitates the installation of the torsion springs 20a, 20b thereon, and the annular grooves on the posts 17a, 17b facilitate the fixation of the end portions of the torsion springs 20a, 20b thereon and prevent the torsion springs 20a, 20b from falling off. Since the roots of the posts 17a, 17b are fixed on the feedback rod R, the torsion springs 20a, 20b are provided with stable support. The torsion springs 20a, 20b are kept in a certain spring space in the valve housing Vb, which is bounded in the axial and transverse directions by the outer boundaries of the upper and lower tabs 15a, 15b of the feedback rod R and in the longitudinal direction by the ends of the posts 17a, 17b, and no additional space is needed for the accommodation and operation of the torsion springs 20a, 20b.

[0041] The inner diameter of the torsion springs 20a, 20b is equal to or slightly larger than the inner diameter of the through hole 22, the through holes 16a, 16b. The fork 2 and the feedback lever R are elastically coupled together by the torsion springs 20a, 20b, forming an assembly of the fork 2 and the feedback lever R, as shown in Figure 4 The feedback lever R and the fork 2 only transmit forces to each other through the torsion springs 20a, 20b. The body 21 of the fork 2 is inserted between the upper and lower tabs 15a, 15b of the feedback lever R, and the through hole 22 is located between and longitudinally aligned with the through holes 16a, 16b. The torsion spring 20a is located on the upper side of the upper tab 15a, and the torsion spring 20b is located on the lower side of the lower tab 15b. The torsion springs 20a, 20b are longitudinally aligned with the through holes 16a, 16b, the through hole 22. The torsion springs 20a, 20b are identical in size, and the torsion springs 20a, 20b are installed between the fork 2 and the feedback lever R with the same size of pre-tightening force. The pre-acting force applied by the fork 2 (through the uprights 17a, 17b respectively) to the feedback lever R through the torsion springs 20a, 20b is equal in size and opposite in direction, so that at the intermediate valve position of the control valve V1, the fork torque acting on the feedback lever R through the fork 2 via the torsion springs 20a, 20b is zero, keeping the feedback lever R in the centered position relative to the fork 2.

[0042] Referring to Figure 9 , the adjustment shaft 3 comprises a cylindrical fixed section 31 and a fixed flange 32 located on the longitudinally first side of the fixed section 31. A sealing groove 33 can be provided in the middle of the fixed section 31 for accommodating a sealing member. A cylindrical eccentric shaft section 34 is formed on the longitudinally second side of the fixed section 31. The diameter of the eccentric shaft section 34 is smaller than that of the fixed section 31, and the center line of the eccentric shaft section 34 is offset relative to the center line of the fixed section 31. A terminal section 35 is formed on the longitudinally second side of the eccentric shaft section 34. The diameter of the terminal section 35 is smaller than that of the eccentric shaft section 34, and the terminal section 35 is coaxial with the fixed section 31. An adjustable adjustment end 36 is formed on the longitudinally first side of the fixed flange 32.

[0043] The outer diameter of the eccentric shaft section 34 is set to form a clearance fit between the inner diameters of the through holes 16a, 16b, the through hole 22, so that the eccentric shaft section 34 can pass through the through holes 16a, 16b, the through hole 22 and freely rotate in the through holes 16a, 16b, the through hole 22. The length of the eccentric shaft section 34 is set to be sufficient to pass through the torsion springs 20a, 20b, the through holes 16a, 16b, the through hole 22 of the assembly of the fork 2 and the feedback lever R, as shown in Figure 4 The outer diameter of the eccentric shaft section 34 is set to form a clearance fit between the inner diameters of the through holes 16a, 16b, the through hole 22, so that the eccentric shaft section 34 can pass through the through holes 16a, 16b, the through hole 22 and freely rotate in the through holes 16a, 16b, the through hole 22. The length of the eccentric shaft section 34 is set to be sufficient to pass through the torsion springs 20a, 20b, the through holes 16a, 16b, the through hole 22 of the assembly of the fork 2 and the feedback lever R, as shown in

[0044] When assembling the adjustment shaft 3 with the fork 2 and the feedback lever R, referring to Figure 2The eccentric shaft segment 34 is sequentially threaded through the torsion spring 20a, the through hole 16a, the through hole 22, the through hole 22 16b, the torsion spring 20b, so that the eccentric shaft segment 34 is surrounded by the torsion springs 20a, 20b, the through holes 16a, 16b, the through hole 22, and the end segment 35 is exposed by the torsion spring 20b. In this way, as shown in Figure 2 , an assembled feedback mechanism is formed. In the assembled state of the feedback mechanism, the feedback lever R is kept in the centered position relative to the fork 2 by the pre-tightening force of the torsion springs 20a, 20b.

[0045] The middle part of the fork 2 is inserted between the upper and lower tabs 15a, 15b of the feedback lever R. The convex rings 22a on the upper and lower sides of the fork 2 contact the upper and lower tabs 15a, 15b. In this way, the contact area between the fork 2 and the feedback lever R can be reduced, and the wear between the fork 2 and the feedback lever R can be reduced.

[0046] The eccentric shaft segment 34 is the only eccentric shaft segment on the adjustment shaft 3, which helps to improve the strength of the shaft diameter at both ends of the eccentric shaft segment 34 on the adjustment shaft 3.

[0047] In addition, as shown in Figure 2 , and referring to Figure 11 , Figure 12 , the prongs 23a, 23b of the fork 2 are inserted into the slot hole 11 of the spool 1, and the valve pin 12 is inserted into the notch 24 of the fork 2. The spool 1 applies an axial thrust to one of the prongs 23a, 23b through the valve pin 12, so that the fork 2 oscillates around the eccentric shaft segment 34 of the adjustment shaft 3, and the fork torque acting on the feedback lever R due to the torsional deformation of the torsion springs 20a, 20b increases. On the other hand, the piston rod C2 acts on the connecting portion 14 of the feedback lever R, also applying a counter torque (also essentially generated by the torsional deformation of the torsion springs 20a, 20b) to the feedback lever R. The sum of the counter torque and the fork torque generates a comprehensive torque, which causes the feedback lever R to deflect by an angle from the centered position relative to the fork 2. The size of the comprehensive torque is positively correlated with the deflection angle of the fork 2 relative to the fork 2.

[0048] The adjustment shaft 3 is adjustably fixed in the valve housing Vb by the fixed segment 31, the fixed flange 32 and the end segment 35. Among them, the fixed segment 31 and the end segment 35 are respectively installed in different components constituting the valve housing Vb. For example, the valve housing Vb is composed of a valve cover and a valve body. The end segment 35 is inserted into the recess hole in the valve body, the fixed segment 31 is threaded through the mounting hole in the valve cover, and the fixed flange 32 is pushed against the sink in the valve cover to determine the longitudinal position of the adjustment shaft 3. The adjustment end 36 is protruded from the first longitudinal side surface (for example, the upper surface) 41 of the valve housing Vb, as shown in Figure 10The adjustment end 36 is shown to be rotatable by an operator from outside the valve housing Vb by an angle. The eccentric shaft section 34 is rotated with the adjustment end 36, thereby fine-tuning the axial position of the yoke 2 and the second end of the feedback lever R relative to the spool 1. The ends of the two posts 17a, 17b on the feedback lever R abut corresponding locations in the valve housing Vb, but the movement of the posts 17a, 17b in the valve housing Vb is not hindered. The corresponding locations in the valve housing Vb provide a limit for the two posts 17a, 17b, thereby defining the longitudinal position of the feedback lever R (and the yoke 2 and the torsion springs 20a, 20b), and also defining the accommodation and working space of the torsion springs 20a, 20b.

[0049] The fixed section 31 and the end section 35 of the adjustment shaft 3 form a tight fit with the valve housing Vb, but allow an operator to fine-tune the angle of the eccentric shaft section 34 through the adjustment end 36. The eccentric shaft section 34 constitutes the shaft section that supports the rotation (swinging) of the yoke 2 and the feedback lever R. The tight fit between the adjustment shaft 3 and the valve housing Vb is set such that the action of the yoke 2 and the feedback lever R does not cause a change in the angle of the eccentric shaft section 34 during operation of the control valve V1. The adjustment shaft 3 is fixed to the valve housing Vb by the tight fit described above, without the need for a gasket.

[0050] The lateral first side surface 42 of the valve housing Vb is a single mating surface for mounting to the pump housing Pb. The lateral first side surface 42 forms an opening 43 to the interior of the valve housing. The lever portion 13 of the feedback lever R extends through the opening 43 into the pump housing Pb, such that the connecting portion 14 is connected to the piston rod C2 in the pump housing Pb. An oil hole 44 is also formed in the lateral first side surface 42 for communicating the internal oil passages of the control valve V1 (including the A port and the B port) with the corresponding oil passages of the pump housing Pb. All the oil ports required for the control valve V1 can be provided on the lateral first side surface 42, i.e. the single mating surface, without the need for oil ports on other surfaces of the valve housing Vb. The above-described configuration makes it easy to assemble the control valve V1 with the pump P, and reduces the machining surfaces of the valve housing Vb and the number of seals.

[0051] When the control valve V1 is operated, the solenoid of one of the two side control ends is energized, causing the plunger 45 (see Fig. 2) of the side control end to move the yoke 2 and the feedback lever R, thereby causing the spool 1 to move to the corresponding position. The other side control end is not energized, and the plunger 45 of the other side control end is held in place by the torsion spring 20a, 20b. The plunger 45 of the other side control end is held in place by the torsion spring 20a, 20b. Figure 12) axial pushing of the spool 1. The spool 1 is axially moved to a corresponding working valve position to connect the control oil passage L through one of the A, B ports of the control valve Vl to one of the two piston cavities of the displacement adjusting mechanism C. The flow area of the control valve Vl depends on the control current of the solenoid. Thus, the control oil from the control oil passage L forces the piston CI to move, which in turn drives the piston rod C3 to move to drive the variable displacement element in the pump P to change the displacement of the pump P. Meanwhile, the valve pin 12 on the spool 1 axially pushes one of the fork arms 23a, 23b, which causes the yoke 2 to swing around the adjusting shaft 3 (the eccentric shaft section 34) to cause the yoke torque of the torsion springs 20a, 20b acting on the feedback lever R to increase. On the other hand, the piston CI drives the piston rod C2 to move to drive the feedback lever R to swing to apply a counteracting torque to the feedback lever R. The sum of the counteracting torque and the yoke torque results in a resultant torque that causes the feedback lever R to deflect from a centered position relative to the yoke 2 by an angle. The resultant torque also acts on the yoke 2 through the torsion springs 20a, 20b, and one of the fork arms 23a, 23b of the yoke 2 provides a force feedback to the spool 1 through the valve pin 12. The force feedback thus provided counteracts the axial pushing force of the plunger 45 applied to the spool 1, and helps to maintain the spool 1 at a predetermined position and flow area corresponding to the control current size of the control end, avoiding oscillation of the spool 1 at the predetermined position and fluctuation of the flow area.

[0052] Referring to Figure 11 , the top and bottom walls on the two longitudinal sides of the spool 1 defining the slot hole 11 have substantially equal thicknesses, so that the fork arms 23a, 23b are substantially located at the longitudinal middle of the spool 1. Thus, the axial pushing force of the valve pin 12 applied to the fork arms 23a, 23b is substantially located at the longitudinal middle of the spool 1. In this way, the longitudinal force of the valve housing Vb acting on the end of the spool 1 caused by the pushing force of the valve pin 12 can be reduced or even avoided, and the wear of the spool 1 can be reduced.

[0053] The control valve according to the present application has a feedback mechanism comprising a combination of a feedback lever, a yoke and a pair of torsion springs, which has simple forms of parts, is easy to process, requires less amount of material, does not need high assembly precision such as the feedback adjusting clamp in the prior art, has less processing procedures and simple assembly process. These factors together result in a reduced cost of the feedback mechanism.

[0054] Those skilled in the art can make various adaptive modifications to the details described above under the principles of the present application.

[0055] For example, in the specific example described above, one end of each of the torsion springs 20a, 20b is connected to the feedback lever R and the other end is connected to the yoke 2 through the fixing pins 25a, 25b, but the torsion springs 20a, 20b can be connected to the feedback lever R and the yoke 2 through other structures.

[0056] Furthermore, in the specific example described above, the control valve V1 is an electric proportional control valve, but the feedback mechanism of the present application can also be used for other control valves requiring force feedback. The valve position and the number of ports of the control valve are not limited to the three valve positions and four ports described above.

[0057] Furthermore, in the specific example described above, the control valve V1 is used for the displacement adjustment mechanism of a bi-directional pump, but the control valve V1 with the feedback mechanism of the present application can also be used for a variable displacement unidirectional pump. Furthermore, since the same displacement adjustment mechanism can be used for various types of variable displacement hydraulic motors, the control valve V1 with the feedback mechanism of the present application can also be used for various variable displacement hydraulic motors.

[0058] While the present application has been described herein with respect to the specific embodiments thereof, the scope of the present application is not limited to the details shown. Various modifications can be made to these details without departing from the spirit of the application.

Claims

1. A control valve comprising: a valve housing (Vb) and a valve spool (1) axially movably arranged in the valve housing (Vb), an axial middle portion of the valve spool (1) being provided with a slot hole (11) transversely passing through the valve spool (1), a valve pin (12) longitudinally passing through the slot hole (11); and a feedback mechanism comprising: an adjusting shaft (3) supported by the valve housing (Vb) and longitudinally extending, the adjusting shaft (3) having an eccentric shaft section (34); a yoke (2) comprising a body (21) and a pair of yoke arms (23a, 23b) transversely extending from the body (21), a yoke through hole (22) longitudinally passing through the body (21), the pair of yoke arms (23a, 23b) being inserted into the slot hole (11), the valve pin (12) being inserted between the pair of yoke arms (23a, 23b); a feedback lever (R) comprising a lever portion (13) transversely extending, a first end of the lever portion (13) forming a connecting portion (14), a second end of the lever portion (13) forming a pair of tabs (15a, 15b) longitudinally facing each other, the body (21) of the yoke (2) being inserted between the pair of tabs (15a, 15b), a tab through hole (16a, 16b) longitudinally passing through each of the pair of tabs (15a, 15b), wherein each of the tabs (15a, 15b) is connected with the body (21) of the yoke (2) by one corresponding pre-tightened torsion spring (20a, 20b) respectively; wherein the eccentric shaft section (34) passes through the yoke through hole (22), the tab through holes (16a, 16b) and the torsion springs (20a, 20b). The pair of tabs (15a, 15b) comprises a first tab (15a) and a second tab (15b), the torsion springs (20a, 20b) comprise a first torsion spring (20a) arranged at a first longitudinal side of the first tab (15a) and a second torsion spring (20b) arranged at a second longitudinal side of the second tab (15b), the first torsion spring (20a) and the second torsion spring (20b) acting on the feedback lever (R) with equal magnitude and opposite directions.

2. The control valve of claim 1, wherein, Each of the tabs (15a, 15b) is respectively provided with a post (17a), both ends of the body (21) are respectively provided with a fixing pin (25a, 25b); 3. The control valve according to claim 1 or 2, wherein A first end of each of the torsion springs (20a, 20b) is sleeved on the corresponding post (17a), a second end of each of the torsion springs (20a, 20b) is inserted into a longitudinal insertion hole on the corresponding fixing pin (25a, 25b). Each of the posts (17a) is fixed on the corresponding tab (15a, 15b) by interference fit, each of the fixing pins (25a, 25b) is fixed on the corresponding end of the body (21) by interference fit.

4. The control valve of claim 3, wherein, The two posts (17a) are longitudinally aligned with each other and extend in opposite longitudinal directions, each of the posts (17a) is a cone, and a ring groove is formed at a position close to the tab (15a, 15b), a first end of the corresponding torsion spring (20a, 20b) is clamped in the ring groove.

5. The control valve according to claim 3 or 4, wherein ​ 6. The control valve of any one of claims 3-5, wherein, The ends of the two uprights (17a) are respectively fitted to corresponding parts inside the valve housing (Vb), thereby defining the longitudinal position of the feedback lever (R) and the shift fork (2) in the valve housing (Vb), and defining the accommodation and working space of the torsion springs (20a, 20b).

7. The control valve of any one of claims 1-6, wherein, The adjusting shaft (3) further has a fixed segment (31) located at the first longitudinal side of the eccentric shaft segment (34) and a terminal segment (35) located at the second longitudinal side of the eccentric shaft segment (34), wherein the center line of the fixed segment (31) is collinear with the center line of the terminal segment (35) and is installed in the valve housing (Vb), and the center line of the eccentric shaft segment (34) is arranged eccentrically relative to the center lines of the fixed segment (31) and the terminal segment (35).

8. The control valve of claim 7, wherein, The adjusting shaft (3) further has an adjusting end (36) located at the first longitudinal side of the fixed segment (31), which is exposed by the valve housing (Vb) and can be rotated to adjust the position of the center line of the eccentric shaft segment (34) relative to the center lines of the fixed segment (31) and the terminal segment (35).

9. The control valve of any one of claims 1-8, wherein, The body (21) of the shift fork (2) has a convex ring (22a) formed on the surface of each of the two opposite longitudinal sides around the opening of the shift fork through hole (22), and the body (21) of the shift fork (2) is in contact with the pair of tabs (15a, 15b) through the convex rings (22a).

10. The control valve of any one of claims 1-9, wherein, The connecting part (14) of the feedback lever (R) is arranged to be connected to the displacement adjusting mechanism of a hydraulic pump or a hydraulic motor, the valve housing (Vb) has a single mating surface, the mating surface is adapted to be connected to the housing of a hydraulic pump or a hydraulic motor, all the oil ports of the control valve are formed on the mating surface, and the feedback lever (R) passes through the opening (43) on the mating surface.

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