JP2008196344A - Variable displacement swash plate type hydraulic pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a transmitting function of a tilting angle and a vibration absorbing function of a swash plate using a feedback link with a simple configuration. <P>SOLUTION: A feedback mechanism 41 provided between a regulator 21 and the swash plate 14 comprises a support pin 42, a feedback lever 43, a feedback pin 44 and the feedback link 45. The feedback link 45 has convex spherical parts 46, 46 formed in the vicinity of both ends of the feedback link 45, and comprises a leaf piece bent so as to be folded back in an intermediate part. A fold-back part 45A is fitted to a columnar rod part 43C of the feedback lever 43. Extension parts 45B, 45B extended from the fold-back part 45A by predetermined length are assembled to an engagement part 48 provided on the side face of the swash plate 14 so as to abut on a pair of regulation walls 48A, 48A provided in forward/backward positions in the tilting direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

    The present invention relates to a variable displacement swash plate hydraulic pump that is suitably used as a hydraulic source of hydraulic equipment mounted on a construction machine such as a hydraulic excavator or a hydraulic crane.

  The variable displacement swash plate hydraulic pump has a hollow casing, a rotation shaft rotatably provided in the casing, and a plurality of cylinders with a constant interval in the circumferential direction, and rotates integrally with the rotation shaft. A cylinder block, a plurality of pistons that are reciprocably fitted in the cylinders of the cylinder block, and a sliding surface on which a shoe attached to the end of each piston slides, and tilts in the casing The swash plate is provided with a swash plate that can be provided and a tilt actuator that tilts the swash plate. Tilt drive of the swash plate is performed by supplying and discharging pressure oil to and from the tilt actuator, and supply and discharge of pressure oil to and from the tilt actuator are controlled by a regulator. A feedback mechanism is provided between the regulator and the swash plate.

  This variable displacement swash plate hydraulic pump can change the discharge amount (pump capacity) of pressure oil from the hydraulic pump by appropriately changing the tilt angle of the swash plate by a tilt actuator. The tilt angle of the swash plate is transmitted to the regulator via a feedback mechanism, so that the supply and discharge of the pressure oil to the tilt actuator by the regulator is feedback controlled so as to correspond to the tilt angle of the swash plate.

  Here, high-frequency vibration is generated in the swash plate having a sliding surface on which the shoe attached to the end of the piston slides due to the discharge pulsation of the hydraulic pump when the cylinder block rotates. For this purpose, in the feedback mechanism that transmits the tilt angle of the swash plate to the regulator, the vibration of the swash plate is transmitted to the feedback link connected to the swash plate, and the feedback link is micro-vibrated toward the tilt direction. If this feedback link is formed of a rigid member such as a steel bar, it may be damaged.

From the above points, the feedback link is formed of an elastic member such as a spring steel material, and the connecting portion to the feedback lever has a round bar shape, but the portion extended from the connecting portion to the feedback lever is thinned. Thus, for example, Patent Document 1 proposes a plate spring shape in which the plate surface of the plate spring portion is directed in the vibration direction of the swash plate.
JP 2003-269324 A

  By the way, the original function of the feedback link is to transmit the tilt angle of the swash plate to the regulator. In order to transmit the tilt angle quickly and accurately, the feedback link has some rigidity. There must be. On the other hand, in order to prevent the feedback link from being damaged or deformed by the high-frequency vibration of the swash plate, it is necessary to provide a high spring property. In other words, the function of transmitting the tilt angle by the feedback link and the function of protecting it from damage or deformation are contradictory, and if one of them is emphasized, the other function is impaired. There is a problem.

  Moreover, since the feedback link by the structure mentioned above needs to make the connection part to a feedback lever into a round bar shape, forming a leaf | plate spring part must be performed by cutting. In addition, it is necessary to provide a connecting mechanism to the swash plate at the tip of the feedback link, which causes a problem that the structure of the feedback lever becomes extremely complicated and difficult to manufacture.

  The present invention has been made in view of the above points, and an object thereof is to improve a tilt angle transmission function and a vibration absorption function of a swash plate by a feedback link having a simple configuration. .

  In order to achieve the above-mentioned object, the present invention makes the discharge capacity variable by supplying and discharging pressure oil to the tilting actuator from the regulator and tilting the swash plate, and tilting the swash plate by a feedback mechanism. A variable displacement swash plate type hydraulic pump that feedback-controls the angle of rotation to the regulator, wherein the feedback mechanism includes a feedback lever that is swingably supported by the casing and a support pin of the feedback lever. A feedback pin connected to the regulator and a feedback link provided on the other side and having a tip engaged with an engaging portion provided on the swash plate, and the feedback link has a spring plate piece at an intermediate position. The folded portion is connected to the feedback lever. The extending portions from the folded portion are spaced apart from each other in a free state, and convex surfaces are formed on the surfaces opposite to the opposing surfaces of the extending portions, respectively. The joint portion has a pair of restricting walls, and the tip portion of the feedback link is disposed between the pair of restricting walls, and the biconvex curved surface portion is assembled so as to abut against the restricting walls. It is characterized by that.

  The feedback link is made of, for example, a metal spring plate piece bent into a hairpin shape, and the folded portion of the feedback link is connected to the feedback lever. In this connection mode, for example, a slit can be provided in the feedback lever, and the feedback link can be sandwiched between the slits. However, the end of the feedback lever has a cylindrical shape having a predetermined diameter, and the spring constituting the feedback link It is desirable that the inner diameter of the folded portion of the plate piece is bent so as to be substantially equal to the outer diameter of the feedback lever and connected so as to be fitted to the feedback lever. When connecting the feedback link so as to be fitted to the feedback lever, it is necessary to fix the feedback link, that is, to prevent the feedback link and to prevent the feedback lever from rotating. The feedback link can be fixed by, for example, welding means, but is preferably fixed by a pin or a screw. These pins or screws are inserted in a direction perpendicular to the axis of the feedback lever.

  In the spring plate piece formed of metal or the like, a convex curved surface portion is formed at a portion on the tip side of the extending portion from the folded portion, and these convex curved surface portions can be, for example, convex spherical surface portions. The convex curved surface portion can be easily formed by pressing means or the like. Thereafter, the folded portion can also be formed using a pressing means or the like, and its manufacture becomes extremely easy as compared with the case of cutting a round bar-like member.

  Both extending portions from both sides of the folded portion are inserted between a pair of regulating walls constituting an engaging portion provided on the swash plate, and these both convex curved portions are brought into contact with the respective regulating walls. At this time, the space between the two extending portions may be in a free state, and can be assembled in a state of being bent to some extent, and further, in the assembled state, the surface on the opposite side to the convex curved surface portion in both extending portions. There is no problem even if they are in contact. However, in order to stably hold the feedback link, it is necessary to prevent a gap from being generated between the wall surface and the convex curved surface portion when inserted between the regulating walls.

  When the swash plate vibrates at a minute amplitude, such as high-frequency vibration of the swash plate due to the discharge pulsation of the hydraulic pump, etc., the feedback link does not absorb this vibration due to its bending, and the tilt change operation of the swash plate Is performed and the feedback link follows this, and transmits the rotation angle of the feedback lever to the regulator. Therefore, minute vibrations such as high-frequency vibrations of the swash plate are not transmitted to the regulator, and when the swash plate is driven to tilt, this tilting operation is reliably transmitted to the regulator.

  If the length of the feedback link, that is, the interval from the connecting portion to the engaging portion of the swash plate to the connecting portion to the feedback lever is increased, the swash plate can be absorbed by the entire feedback lever. In this case, the two extending portions constituting the feedback lever can be assembled to the engaging portion in a state where they are in contact with each other. More preferably, when the minute vibration occurs, the vibration is transmitted to the extending portion on one side of the feedback link, and is transmitted to the regulator through the extending portions on both sides when the swash plate is tilted. For this purpose, a gap is formed between the two extending portions, and it is most preferable to form a gap that is substantially the same as or slightly larger than the vibration width of the minute vibration of the swash plate. desirable.

  The feedback link can be easily manufactured with a simple configuration, and the change in the tilt angle of the swash plate can be accurately transmitted to the regulator, and the vibration of the swash plate can be effectively absorbed by the cylinder block operation. As a result, the durability of the feedback link is improved.

    Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 show an embodiment of a variable displacement swash plate hydraulic pump according to the present invention. In the figure, reference numeral 1 denotes a casing of a hydraulic pump. The casing 1 includes a casing body 2, a front casing 3 that covers the front side of the casing body 2, and a rear casing that covers the rear side of the casing body 2. 4. In the internal space of the casing body 2, the rear casing 4 side is a small-diameter cylinder block housing portion 2A, and the front casing 3 side is a large-diameter swash plate housing portion 2B.

  Reference numeral 5 denotes a rotating shaft, and the rotating shaft 5 is rotatably supported by bearings 6 and 7. The rotating shaft 5 is rotatably supported by the front casing 3 at the intermediate portion thereof by the bearing 6 and guided into the casing body 2, and the end portion thereof is rotatably supported by the rear casing 4 by the bearing 7. The other end portion of the rotating shaft 5 protrudes outside from the front casing 3, and the protruding end side is connected to an engine (not shown), and the rotating shaft 5 is driven to rotate by the engine.

  A cylinder block 8 is rotatably provided in the cylinder block housing portion 2A in the space inside the casing body 2, and this cylinder block 8 is spline-coupled to the axial intermediate portion of the rotating shaft 5. Rotates integrally with the rotary shaft 5. The outer peripheral surface of the cylinder block 8 has a cylindrical shape, and a substantially annular gap is formed between the inner peripheral surface of the portion of the cylinder body 2 in the casing body 2. The cylinder block 8 has a plurality of cylinders 9 formed in the axial direction. These cylinders 9 are provided at regular intervals in the circumferential direction so as to surround the rotating shaft 5.

  A valve plate 10 is disposed between the rear casing 4 and the cylinder block 8, and the valve plate 10 is fixed to the rear casing 4. As shown in FIG. 2, the valve plate 10 has a pair of supply / discharge ports 10A, 10B having an eyebrow shape intermittently communicating with the cylinders 9 of the cylinder block 8, and the supply / discharge ports 10A, 10B. Is communicated with a supply / discharge passage (not shown) formed in the rear casing 4. In each cylinder 9 of the cylinder block 8, a piston 11 is slidably fitted. A shoe 12 is pivotally connected to the end of each piston 11 protruding from the cylinder 9. Each shoe 12 is engaged with a shoe presser 13. The shoe presser 13 is formed in an annular shape on the sliding surface 14A of the swash plate 14, and each shoe 12 is always in sliding contact with the sliding surface 14A and is guided circumferentially along the sliding surface 14A. It is like that.

  When the cylinder block 8 rotates, the shoe 12 slides along the sliding surface 14A. At this time, if the swash plate 14 is inclined with respect to the axis of the cylinder block 8, the piston 11 responds to this inclination angle. It will reciprocate in the cylinder 9 with a long stroke. While the cylinder 9 is passing through one supply / discharge port 10A of the valve plate 10 due to the rotation of the cylinder block 8, the hydraulic oil sucked into the cylinder 9 is pressurized, passes through the dead center position, and the valve plate 10 When the state is switched to the state through the other supply / discharge port 10B, pressurized hydraulic oil is discharged.

  In order to tilt the swash plate 14, the back surface portion of the swash plate 14 is in contact with a swash plate support member 15 disposed in the swash plate accommodating portion 2 </ b> B of the casing body 2. The plate support member 15 is formed with sliding surfaces 14B and 15A having arcuate sides on both sides of the rotating shaft 5. In order to drive the swash plate 14 to tilt, tilt actuators 16 and 17 are provided at the front and rear positions of the cylinder block 8 in the tilt direction in the casing body 2. These tilting actuators 16 and 17 include bottomed tilting cylinders 16A and 17A formed in the casing body 2, and tilting pistons 16B and 17B slidably fitted in the tilting cylinders 16A and 17A. And springs 16C and 17C for urging the tilting pistons 16B and 17B toward the swash plate 14 side. These tilting pistons 16B and 17B are in contact with the piston contact surfaces 14C and 14D of the swash plate 14. The swash plate 14 is tilted about the tilt center P by being pressed by the tilt pistons 16B and 17B, and the tilt angle θ with respect to the rotation shaft 5 is changed. Thereby, the stroke amount of each piston 11 is adjusted, and the discharge amount (pump capacity) of the pressure oil from the hydraulic pump is variably controlled according to the magnitude of the tilt angle θ.

  The tilt actuator 16 is disposed at a position corresponding to the bottom dead center side of each piston 11, and the tilt actuator 17 is disposed at a position corresponding to the top dead center side of each piston 11. Further, the tilting piston 17B has a larger diameter than the tilting piston 16B, and the pressure receiving area of the tilting piston 17B is set larger than the pressure receiving area of the tilting piston 16B.

  Here, as shown in FIG. 4, the tilt cylinder 16 </ b> A of the tilt actuator 16 is connected to an external hydraulic power source 19 via an oil passage 18. Then, the tilt actuator 16 presses the swash plate 14 (piston contact surface 14C) by the tilt piston 16B by the tilt control pressure oil supplied from the external hydraulic source 19 into the tilt cylinder 16, The swash plate 14 is tilted in the direction in which the tilt angle θ increases (the direction of arrow A in FIG. 4).

  On the other hand, the tilt cylinder 17A of the tilt actuator 17 is connected to the external hydraulic power source 19 via the oil passage 20, the regulator 21, and the like. Then, the tilting actuator 17 is supplied with pressure oil from the external hydraulic power source 19 into the tilting cylinder 17A via the regulator 21, so that the tilting piston 17B moves the swash plate 14 (piston contact surface 14D). The swash plate 14 is pressed and tilted in the direction (indicated by the arrow B in FIG. 4) in which the tilt angle θ decreases. The regulator 21 is for controlling the supply and discharge of pressure oil to the tilt cylinder 17A of the tilt actuator 17.

  A manually operated capacity control valve 23 is provided in the valve housing 22 of the regulator 21, and the capacity control valve 23 slides in the valve housing 22 in the axial direction, as is apparent from FIGS. 3 and 4. A cylindrical sleeve 24 is provided so as to be movable, and a spool 25 is slidably fitted into the sleeve 24. An operation lever 26 is connected to the spool 25 for setting the tilt angle θ of the swash plate 14 by manual operation of an operator or the like.

  The capacity control valve 23 is switched from the neutral position (a) to the switching position (b) or (c) by the operation lever 26, and when switched to the switching position (b), the tilt cylinder 17A of the tilt actuator 17 is tanked. 27, the swash plate 14 is tilted in the direction (indicated by arrow A) in which the tilt angle θ increases. On the other hand, when switched to the switching position (c), the tilting cylinder 17A of the tilting actuator 17 is communicated with the external hydraulic power source 19, and the tilting angle θ of the swash plate 14 is resisted against the pressing force of the tilting actuator 16. It is the structure which tilts in the direction (arrow B direction) which becomes small.

  A capacity control valve 28 for feedback control is provided in the valve housing 22 of the regulator 21, and the capacity control valve 28 is a cylindrical shape provided in the valve housing 22 so as to be slidable in the axial direction. A sleeve 29 and a spool 30 slidably inserted into the sleeve 29 are provided. The spool 30 is provided with an urging means 31 and a hydraulic pilot portion 32, and the hydraulic pilot portion 32 is connected to the discharge side of the hydraulic pump via a pilot passage 33.

  The displacement control valve 28 is switched from the neutral position (d) to the switching position (e) or (f) according to the pump discharge pressure supplied from the hydraulic pump to the hydraulic pilot unit 32, and the tilt actuator 17 is tilted. Controls the supply and discharge of pressure oil to and from the rolling cylinder 17A. Accordingly, the discharge amount (pump capacity) of the pressure oil from the hydraulic pump is limited in accordance with the pump discharge pressure, and an overload acting on the engine or the like can be suppressed.

  Here, the valve housing 22 and the displacement control valve 23 are connected to a tilt cylinder 17A of the tilt actuator 17 via a pump port 22A connected to the external hydraulic pressure source 19 and a displacement control valve 28 described later. A supply / discharge port 22B and a tank port 22C connected to the tank 27 are provided. Further, between the valve housing 22 and the capacity control valve 28, a pump port 22D connected to the external hydraulic source 19, a supply / discharge port 22E connected to the tilt cylinder 17A of the tilt actuator 17, and a capacity control valve 23 are provided. A tank port 22F connected to the tank 27 is provided.

  Reference numeral 41 denotes a feedback mechanism provided between the regulator 21 and the swash plate 14, and this feedback mechanism 41 is swingably disposed in an opening 2 </ b> C provided in the casing body 2 as shown in FIG. 3. The pressure oil supply / discharge operation performed by the regulator 21 with respect to the tilt actuator 17 is feedback-controlled according to the tilt angle θ of the swash plate 14. As shown in FIGS. 5 to 7, the feedback mechanism 41 includes a support pin 42, a feedback lever 43, a feedback pin 44, and a feedback link 45.

  The support pin 42 supports the feedback lever 43 on the casing body 2 so as to be swingable. The support pin 42 is formed in a columnar shape using, for example, a bar steel material. The support pin 42 is rotatably inserted into a pin insertion hole 43A provided at a substantially intermediate position in the length direction of the feedback lever 43 and protrudes from both sides of the feedback lever 43. Both side portions are two parallel plane portions 42A and 42A formed by cutting. As shown in FIGS. 3 and 6, the support pin 42 has concave portions 2 </ b> D and 2 </ b> D provided in the casing body 2 with the flat portions 42 </ b> A provided at both ends in the axial direction sandwiching the opening 2 </ b> C. By attaching to the casing body 2, the casing body 2 is attached in a non-rotating state.

  The feedback lever 43 that is swingably supported by the support pin 42 has a substantially long block shape using, for example, steel. A pin insertion hole 43 </ b> B is provided on one end side in the length direction of the feedback lever 43. The intermediate portion of the feedback pin 44 in the axial direction is fixedly inserted into the pin insertion hole 43B of the feedback lever 43, and both end portions thereof are engagement grooves provided in the sleeves 24 and 29 of the capacity control valves 23 and 28. 24A and 29A are slidably engaged.

  The other end side of the feedback lever 43 is a cylindrical rod portion 43C, and a feedback link 45 is connected to the cylindrical rod portion 43C. The feedback link 45 is formed of a spring plate made of an elastic material such as spring steel, for example, and the spring plate uses a pressing means in the vicinity of both ends to form convex spherical portions 46 and 46 protruding on the same side. In the intermediate portion, the convex spherical portion 46 is formed so that the protruding side faces outward and is bent so as to be folded back, and has a generally hairpin shape. This folding can also be formed by pressing means.

  Accordingly, the feedback link 45 has extending portions 45B and 45B extending a predetermined length from the folded portion 45A. The folded portion 45A has an arc shape and the inner diameter thereof is a cylindrical rod of the feedback lever 43. The portion 43C has substantially the same size as the outer diameter. Therefore, the feedback link 45 is connected by fitting the folded portion 45 </ b> A to the cylindrical rod portion 43 </ b> C of the feedback lever 43. As is apparent from FIG. 8, pin insertion holes 45 </ b> C and 45 </ b> C are formed in the folded portion 45 </ b> A of the feedback link 45, and between the feedback link 45 and the cylindrical rod portion 43 </ b> C of the feedback lever 43. By attaching the fastening pins 47, 47 in the direction orthogonal to the axis from the left and right, it is intended to prevent the slipping off and the relative rotation.

  In the feedback link 45, the tip portion provided with the convex spherical surface portion 46 is engaged with an engaging portion 48 provided on the side surface of the swash plate 14. The engaging portion 48 is composed of a pair of restricting walls 48A and 48A provided at positions before and after the tilting direction. The extending portions 45B and 45B of the feedback link 45 are inserted into the gaps formed by the restricting walls 48A and 48A, and the both convex spherical portions 46 and 46 are pressed against the inner surfaces of the restricting walls 48A and 48A. The contact is made so that pressure acts. That is, as shown in FIG. 9, when the feedback link 45 is in a free state, the two extending portions 45B and 45B are separated from each other as shown by phantom lines in FIG. When engaged, it should be slightly deflected in a direction close to each other. As a result, the both convex spherical portions 46 are held in a state where they are pressed against the regulating wall 48A by the amount of bending, and a minute gap G is formed between the extending portions 45B and 45B.

  The swash plate 14 generates high-frequency vibration due to the influence of the discharge pulsation of the hydraulic pump, and this high-frequency vibration is transmitted to the feedback link 45 via the engaging portion 48. Here, since the feedback link 45 is a member having a spring property, the extension portion 45B is elastically deformed by this vibration. In addition, both the extending portions 45B are pressed against the regulating wall 48A with a predetermined bending allowance, and a gap G is formed between the both extending portions 45B and 45B. If the vibration width is larger than the vibration width, even if the swash plate 14 is vibrated at a high frequency during the operation of the hydraulic pump, both the extending portions 45B and 45B can be elastically deformed independently of each other to absorb the vibration. . Therefore, the bending allowance by the feedback link 45 and the gap G are set to the minimum necessary for absorbing high-frequency vibration. Accordingly, when the swash plate 14 is tilted, both extending portions 45B of the feedback link 45 come into contact with each other, and a driving force for two sheets is obtained. As a result, the rigidity of the feedback link 45 is increased, and the tilt driving operation is reliably transmitted to the feedback lever 43 during the tilting operation.

  Next, the operation of the variable displacement swash plate hydraulic pump having the above configuration will be described. When the rotary shaft 5 is rotationally driven by the engine, the cylinder block 8 rotates integrally with the rotary shaft 5. When the swash plate 14 is inclined with respect to the rotating shaft 5, the shoe 12 provided at the end of each piston 11 is pressed against the sliding surface 14 </ b> A of the swash plate 14 by the shoe presser 13. It slides so as to draw a circular locus on the sliding surface 14A. Thereby, each piston 11 reciprocates in each cylinder 9 of the cylinder block 8, and hydraulic oil is sucked into the cylinder 9 while each piston 11 moves from the top dead center side to the bottom dead center side. When the hydraulic oil in the cylinder 9 is pressurized while the piston 11 moves from the bottom dead center side to the top dead center side, the hydraulic oil is discharged from the hydraulic pump.

  Here, for example, when the discharge amount (pump capacity) of the pressure oil from the hydraulic pump is reduced, this capacity control is performed by the operator or the like operating the operation lever 26 of the capacity control valve 23 constituting the regulator 21. The valve 23 is switched from the neutral position (a) to the switching position (c). As a result, pressure oil for tilt control is supplied from the external hydraulic power source 19 to the tilt cylinder 17A of the tilt actuator 17, and the tilt piston 17B presses the swash plate 14. For this reason, the swash plate 14 is tilted in the direction in which the tilt angle θ decreases against the pressing force from the tilt actuator 16 (tilt piston 16B) (the direction indicated by the arrow B in FIGS. 4 and 7). The As a result, the stroke amount of each piston 11 is reduced, and the pump capacity can be reduced.

  When the tilt angle θ of the swash plate 14 is changed by the tilt actuator 17, the feedback link 45 of the feedback mechanism 41 is engaged with the engaging portions 48 provided on the swash plate 14 at both extending portions 45 </ b> B. Therefore, the tilting operation is performed following the tilting operation of the swash plate 14. As a result, the feedback lever 43 swings in the direction of arrow C in FIG. 6 with the support pin 42 as a fulcrum according to the tilt angle θ of the swash plate 14. Then, the swing displacement of the feedback lever 43 is transmitted to the sleeve 24 of the capacity control valve 23 via the feedback pin 44, and the sleeve 24 is slid and displaced in the axial direction. The supply of pressure oil to the rolling cylinder 17A) is feedback-controlled according to the tilt angle θ (target tilt angle) of the swash plate 14 set by the operation lever 6.

  On the other hand, the pressure oil discharged from the hydraulic pump is supplied as a pilot pressure for capacity control to the hydraulic pilot section 32 of the capacity control valve 28 constituting the regulator 21 through the pilot passage 33. Accordingly, the capacity control valve 28 variably controls the pump capacity (pressure oil discharge amount) Q according to the pump discharge pressure P along the characteristic line 50 of the pump output horsepower shown in FIG.

  That is, when the pump discharge pressure P increases, the pilot pressure supplied to the hydraulic pilot section 32 of the capacity control valve 28 increases, so that the spool 30 resists the valve spring 31 from the neutral position (d) to the switching position ( Switch to f). Thereby, pressure oil for tilt control from the external hydraulic power source 19 is supplied to the tilt cylinder 17A of the tilt actuator 17, and the tilt piston 17B of the tilt actuator 17 presses the swash plate 14. For this reason, the swash plate 14 is tilted in a direction (arrow B direction) in which the tilt angle θ decreases against the pressing force from the tilt actuator 16, so that the pump capacity Q can be reduced. .

  The tilting operation of the swash plate 14 at this time is transmitted to the feedback link 45 of the feedback mechanism 41 through the engagement groove 46, and the feedback lever 43 swings in the direction indicated by the arrow C with the support pin 42 as a fulcrum. To do. Then, the swinging displacement of the feedback lever 43 is transmitted to the sleeve 29 of the capacity control valve 28 via the feedback pin 44, and the sleeve 29 is slid in the axial direction, whereby the pressure oil for the tilting actuator 17 is compressed. Can be feedback-controlled in accordance with the tilt angle θ (target tilt angle) of the swash plate 14 set by the pump discharge pressure P.

  When the tilt angle θ (pump capacity Q) of the swash plate 14 corresponds to the pump discharge pressure P, the pilot pressure supplied to the hydraulic pilot portion 32 of the capacity control valve 28 and the valve spring 31 are balanced. As a result, the capacity control valve 28 returns to the neutral position (d). In this way, the relationship between the pump discharge pressure P and the pump capacity Q is controlled along the characteristic line 50 shown in FIG. 10, and is suppressed to be smaller than the characteristic line 51 indicating the engine horsepower, so that the engine is overloaded. It is possible to prevent the engine stall from occurring.

  Here, in order to accurately perform the feedback control by the regulator 21, the movement of the swash plate 14 in the tilting direction must be reliably transmitted to the regulator 21. On the other hand, the swash plate 14 is connected to the cylinder block 8 via the piston 11 and the shoe 12, and the swash plate 14 vibrates at high frequency due to discharge pulsation or the like acting on the cylinder block 8. The feedback mechanism 41 accurately transmits the tilting operation of the swash plate 14 to the regulator 21. However, the feedback mechanism 41 effectively attenuates the high frequency vibration of the swash plate 14 so that the feedback mechanism 41 is not damaged. Avoid transmitting vibrations.

  Since the high-frequency vibration of the swash plate 14, that is, a small movement, acts on only one extending portion 45B of the feedback link 45 as shown by arrows in FIGS. 11 and 12, depending on the vibration direction. This high-frequency vibration is effectively absorbed by the elasticity of the extending portion 45B, and an excessive load acts on the feedback link 45 and the connecting portion of the feedback link 45 to the feedback lever 43 to damage it. There is no fear of it.

  In addition, the tilting movement of the swash plate 14 is a movement larger than the high-frequency vibration, and when this large movement is applied, whether the tilting angle is increased or the tilting angle is reduced, depending on the tilting direction. As shown by the arrows in FIGS. 13 and 14, one of the extending portions 45B is pushed by the restriction wall 48A and comes into contact with the other extending portion 45B, so that the two extending portions 45B and 45B Since the rotational force acts on the feedback lever 43 due to the rigidity, as described above, even if the degree of elasticity of one extending portion 45B is increased, a sufficient driving force is exerted on the feedback lever 43. be able to. Therefore, an accurate feedback function is exhibited.

  As a result, the feedback link 45 can be prevented from being damaged and its durability can be enhanced. Further, by suppressing the vibration of the swash plate 14 from being transmitted to the sleeves 24 and 29 of the capacity control valves 23 and 28 via the feedback mechanism 41, it is possible to prevent malfunctions of the capacity control valves 23 and 28. Feedback control according to the tilt angle θ of the swash plate 14 can be performed with high accuracy, and the reliability of the hydraulic pump can be improved. That is, the feedback lever 43 of the feedback mechanism 41 swings smoothly and accurately with the support pin 42 fixed to the concave groove 2D provided in the casing body 2 as a fulcrum, and is appropriate for the tilting operation of the swash plate 14. The tilting action of the swash plate 14 transmitted to the feedback link 45 can be accurately applied to the capacity control valves 23 and 28 (sleeves 24 and 29) of the regulator 21 via the feedback lever 43 and the feedback pin 44. Can tell. Thereby, the regulator 21 can perform feedback control with high accuracy according to the tilt angle θ of the swash plate 14.

1 is a cross-sectional view showing a variable displacement swash plate hydraulic pump according to a first embodiment of the present invention. It is XX sectional drawing in FIG. It is a principal part expanded sectional view of FIG. It is a hydraulic circuit diagram which shows hydraulic systems, such as a tilt actuator and a regulator. It is a perspective view which shows a feedback mechanism. It is YY sectional drawing of FIG. It is a principal part external view which shows a cylinder block, a swash plate, a tilt drive mechanism, and a feedback mechanism. It is a top view of a feedback link. It is a top view which shows the engagement state of a feedback link and an engaging part. It is a characteristic diagram which shows the relationship between the discharge pressure of a variable capacity type | mold swash plate type hydraulic pump, and pump capacity | capacitance. It is operation | movement explanatory drawing of the feedback link at the time of the minute vibration of a swash plate. It is another action explanatory view of the feedback link at the time of minute vibration of a swash plate. It is action | operation explanatory drawing of the feedback link at the time of tilting operation | movement of a swash plate. It is another action explanatory drawing of the feedback link at the time of tilting operation of a swash plate.

Explanation of symbols

2 Casing body 5 Rotating shaft 8 Cylinder block 9 Cylinder 11 Piston 12 Shoe 14 Swash plate 14A Sliding surface 16, 17 Tilt actuator 21 Regulator 23, 28 Capacity control valve 41 Feedback mechanism 42 Support pin 43 Feedback lever 44 Feedback pin 45 Feedback Link 45A Folding part 45B Extension part 46 Convex spherical surface part 47 Fastening pin 48 Engagement part 48A Restriction wall

Claims (3)

The discharge capacity is made variable by supplying and discharging pressure oil from the regulator to the tilt actuator and tilting the swash plate, and the tilt angle of the swash plate is feedback controlled to the regulator by a feedback mechanism. In plate hydraulic pump,
The feedback mechanism is provided on one side with a feedback lever supported swingably on the casing, a support pin of the feedback lever, a feedback pin connected to the regulator, and provided on the other side. A feedback link that engages with an engaging portion provided on the swash plate;
The feedback link is formed by bending the spring plate piece at an intermediate position, the folded portion is connected to the feedback lever, and both extending portions from the folded portion are separated from each other in a free state. A convex curved surface portion is formed on the surface opposite to the opposing surfaces of these two extending portions,
The engaging portion has a pair of restricting walls, and a tip end portion of the feedback link is disposed between the pair of restricting walls, and the biconvex curved surface portion is assembled so as to contact the restricting walls. A variable displacement swash plate hydraulic pump characterized by having a configuration as described above. The connecting portion of the feedback lever to the feedback link has a cylindrical shape in which the folded portion is fitted, and the folded portion is fitted to the feedback lever, and is not relatively rotatable by a pin or a screw, and 2. The variable displacement swash plate hydraulic pump according to claim 1, wherein the variable displacement swash plate hydraulic pump is connected so as not to be separated. The biconvex curved surface portion formed on the feedback link is mounted so as to be separated from the vibration width of the tip of the feedback link due to the vibration of the swash plate when the biconvex curved surface portion comes into contact with each regulation wall. The variable displacement swash plate hydraulic pump according to claim 1 or 2.

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