JP7235309B2 - Axial piston device - Google Patents

Description

The present invention relates to an axial piston device comprising an axial piston member, a movable swash plate that changes the volume of the axial piston member, and a hydraulic servomechanism that generates an operating force for tilting the movable swash plate. .

An axial piston device comprising an axial piston member and a movable swash plate that changes the volume of the axial piston member in accordance with a tilt position about a swing axis, wherein the movable swash plate is tilted about the swing axis. A configuration including a hydraulic servo mechanism that generates an operating force for rotating has been proposed and used (see Patent Document 1 below).

An axial piston device having such a configuration is useful in that it can reduce the manual operation force required to tilt the movable swash plate.

However, the conventional axial piston device has room for improvement in terms of miniaturization and simplification of the hydraulic servomechanism.

JP 2015-055180 A

The present invention has been made in view of the above-mentioned prior art, and is an axial piston device having a hydraulic servomechanism that generates an operating force for tilting a movable swash plate, wherein the hydraulic servomechanism is reduced in size and simplified. The object is to provide a feasible axial piston device.

In order to achieve the above object, the present invention provides a housing, a rotating shaft supported by the housing so as to be rotatable about its axis, and an axial shaft housed in the housing while being supported by the rotating shaft so as not to rotate relative to the shaft. A piston member, a movable swash plate that changes the volume of the axial piston member according to a tilt position about the swing axis, and a hydraulic servo that generates an operating force to tilt the movable swash plate about the swing axis. The hydraulic servomechanism liquid-tightly defines first and second oil chambers at one longitudinal end and the other longitudinal end of a servo space formed in the housing. is moved in the first axial direction by pressure oil supply to the first oil chamber and pressure oil discharge from the second oil chamber, and pressure oil supply to the second oil chamber and the first oil a servo piston that is moved in the second axial direction by discharging pressure oil from the chamber; a connecting arm that tilts in two directions; a pressure oil line that receives pressure oil from a hydraulic source; first and second supply and discharge lines that are fluidly connected to the first and second oil chambers; and a drain line; A switching valve set for switching connection states of the pressure oil line, the first supply/discharge line, the second supply/discharge line, and the drain line, the set being liquid-tight in an installation hole formed in the housing and rotatable around an axis. and a second valve shaft rotatably accommodated in the axis hole of the first valve shaft, one of the first and second valve shafts acting as an input valve shaft. and a switching valve set in which the other of the first and second valve shafts acts as a feedback valve shaft, and the feedback valve shaft is rotated about an axis relative to the input valve shaft according to the movement of the connecting arm. and a feedback arm.

In one aspect, the installation hole is provided with an inflow port to which the pressure oil line is fluidly connected, and first and second connection ports to which the first and second supply/discharge lines are fluidly connected, respectively. , the drain line has a drain oil passage formed in the second valve shaft.

The first valve shaft has an inflow opening and a first connection opening at different positions in the circumferential direction for communicating the inflow port, the first connection port, and the second connection port with the axial holes of the first valve shaft, respectively. and a second connection opening are provided.

The second valve shaft has a drain area in which an inlet end of the drain oil passage is opened at different positions in the circumferential direction, and the inflow port can be selectively fluidly connected to the first and second connection ports. It has an oil passage region and first and second blocking regions capable of blocking the first and second connection ports, respectively.

In this case, when the input valve shaft is rotated about the axis with respect to the feedback valve shaft in one of the first direction and the second direction, the inflow port is connected to the first and second connections through the oil passage region. With only one of the ports fluidly connected and the other of the first and second connecting ports fluidly connected through the drain region to the inlet end of the drain line, the servo piston moves in the corresponding axial direction. While the actuated state is present, when the feedback valve shaft is axially rotated relative to the input valve shaft via the feedback arm in response to the axial movement of the servo piston, the first and second connection ports are blocked by the first and second blocking regions, respectively, and the holding state in which the position of the servo piston is held in the axial direction is exhibited.

In the one aspect, preferably, the first valve shaft is positioned between the first and second connection openings in the circumferential direction, and is located between the first and second connection ports on the inner peripheral surface of the installation hole. and an intermediate arc region that can slide in a liquid-tight manner with respect to the circumference direction, extending from the intermediate arc region to the side adjacent to the inflow opening through the first connection opening in the circumferential direction, between the first connection port and the inflow port. a first arcuate area that can liquid-tightly slide on the inner peripheral surface of the installation hole; A second arcuate region is provided between the two connection ports and the inflow port and is capable of liquid-tightly slidably contacting the inner peripheral surface of the installation hole.

In the above aspect, preferably, the drain area is positioned between the first and second closed areas in the circumferential direction, and the drain oil passage drains the drain oil that has flowed in from the inlet end to the housing. configured to open to the interior space of the

In the above-described various configurations, the housing includes a first end wall portion that supports a first end portion of the rotating shaft closer to the swash plate main body of the movable swash plate than the axial piston member so as to be rotatable around the axis. a second end wall portion for supporting a second end portion of the rotating shaft opposite to the first end portion so as to be rotatable around the axis; and peripheral edges of the first and second end wall portions are connected to each other The peripheral wall portion is provided with a bearing portion that supports the swash plate shaft of the movable swash plate and a radial opening that opens the bearing portion outward.

In this case, preferably, the housing further includes a lid detachably attached to the peripheral wall so as to close the radial opening, and the switching valve set is supported by the lid. can be

Preferably, the servo space is located at a corner of the housing where the first end wall is connected to the vicinity of the area of the peripheral wall where the radial opening is provided. It is provided so as to be orthogonal to both of the swing axes.

Preferably, the installation hole is formed in the lid body so that its axis is parallel to the swing axis of the movable swash plate, and the feedback arm has a proximal end that is not rotatable relative to the feedback valve shaft about the axis. A free end of the connecting arm extends in a direction orthogonal to the axis of the switching valve set in a connected state, and the base end of the connecting arm is connected to the shaft of the movable swash plate so as not to rotate relative to the axis and is freely movable. The swash plate extends in a direction perpendicular to the swing axis of the movable swash plate while the end is engaged with the servo piston.

In this case, the feedback arm and the connecting arm are operatively connected via an uneven structure that can be engaged and disengaged according to the attachment and detachment of the lid to and from the peripheral wall portion.

For example, the housing integrally includes the first end wall portion and the peripheral wall portion, a case body having an opening on the opposite side of the peripheral wall portion to the first end wall portion, and a case body that closes the opening. and a port block detachably connected to the case body to form the second end wall.

The form in which the housing has the lid preferably includes a reference position biasing mechanism that biases the input valve shaft toward the reference position around the axis.

The reference position urging mechanism includes a reference position arm extending in a direction orthogonal to the input valve shaft with its base end connected to the input valve shaft so as not to rotate relative to the axis, and a reference position arm parallel to the swing axis. and an engaging pin erected on the reference position arm is accommodated in an accommodating space formed in the lid so that the longitudinal direction is perpendicular to the swing axis so that the engaging pin can freely move in the longitudinal direction. It has a reference position piston whose ends are engaged and a reference position biasing member that biases the reference position piston toward a longitudinal reference position corresponding to the reference position around the axis of the input valve shaft.

In a first aspect, the first valve shaft and the second valve shaft act as the feedback valve shaft and the input valve shaft, respectively, and the second valve shaft has an outer end that is manually operated. configured to form a possible operating input.

In the second aspect, the first valve shaft and the second valve shaft act as the input valve shaft and the feedback valve shaft, respectively, and the first valve shaft is the second valve shaft. The inner end surface of the axial hole to be inserted is opened, and the outer end portion is configured to form an operation input portion capable of being manually operated.

In the third aspect, the axial piston device further includes an operating member that is manually operated, an operating sensor that detects an operating state of the operating member, a hydraulic operating mechanism that rotates the input valve shaft around its axis, and a control device that controls the operation of the hydraulic operation mechanism.

The hydraulic operation mechanism includes an operation arm that extends in a direction orthogonal to the input valve shaft with its base end connected to the input valve shaft so as not to rotate relative to the axis, and an operation arm that extends in a direction orthogonal to the input valve shaft, and The first and second operating oil chambers are accommodated in the accommodating space in a liquid-tight manner at one end and the other end in the longitudinal direction of the accommodating space formed in the housing. It is moved in the first longitudinal direction by pressure oil supply and pressure oil discharge from the second operation oil chamber, and is moved in the first longitudinal direction by pressure oil supply to the second operation oil chamber and pressure oil discharge from the first operation oil chamber. an operating piston that is longitudinally displaced, and the operating piston such that in response to first and second longitudinal movements of the operating piston, the input valve shaft is rotated about an axis in first and second directions, respectively; a connecting member for operatively connecting the piston and the operating arm; first and second operation biasing members respectively disposed in the first and second input oil chambers so as to clamp the operating piston; An operation pressure oil line for receiving pressure oil, an operation drain line, and first and second electromagnetic proportional valves for switching supply and discharge of pressure oil to and from the first and second operation oil chambers are provided.

The first and second electromagnetic proportional valves are connected to the operation pressure oil line while blocking the corresponding operation oil chamber from the operation drain line. A holding state in which both the pressure oil line and the operation drain line are blocked, and a pressure oil discharge state in which the corresponding operation oil chamber is connected to the operation drain line while blocking the operation pressure oil line. configured to obtain.

The control device controls the operation of the first and second electromagnetic proportional valves based on the signal from the operation sensor so that the input valve shaft is located at a position around the axis corresponding to the operation state of the operation member. shall be performed.

In the third aspect, for example, the first and second electromagnetic proportional valves are composed of a main body having a driving portion, an initial position for exhibiting the holding state, a projecting position for exhibiting the pressure oil supply state, and the pressure and a spool axially retractably housed in the main body so as to be able to assume a retracted position for exhibiting an oil draining state.
The driving unit is in an ON state in which the spool is forcibly pushed in a protruding direction and positioned at the protruding position based on a control signal from the control device, and an ON state in which the spool is not substantially applied with a pushing force. The spool has an oil chamber side pressure receiving portion that receives the pressure of the operating oil chamber and generates a retracting direction pushing force that pushes the spool in the retracting direction, and the drive is in the OFF state, the pressure in the operation oil chamber is substantially zero, the initial position is taken in equilibrium with the operation drain line, and the pushing force in the retracting direction exceeds the pressure in the operation drain line. In the state it is configured to assume a retracted position.

In this case, preferably, the drive section has a pin that contacts the base end surface of the spool and pushes the spool in the protruding direction in the ON state. In the OFF state, the drive unit allows the spool to take the initial position in the equilibrium state and the retracted position in the oil chamber hydraulic pressure generation state. The pin is configured to be biased toward the proximal end surface of the spool so that the contact state of the proximal end surface of the spool is maintained.

According to the axial piston device of the present invention, the hydraulic servomechanism that generates the operating force for tilting the movable swash plate can be made as small and simple as possible.

FIG. 1 is a hydraulic circuit diagram of an axial piston device according to Embodiment 1 of the present invention. FIG. 2 is a sectional view of the axial piston device according to the first embodiment. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2. FIG. 5 is an enlarged view of the V portion in FIG. 3. FIG. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 5. FIG. FIG. 8 is an exploded perspective view of main constituent members and the first swash plate of the hydraulic servo mechanism in the axial piston device according to the first embodiment. FIG. 9 is a partial cross-sectional view corresponding to FIG. 6, showing a state in which the second valve shaft is operated in the first direction around the axis with respect to the first valve shaft. FIG. 10 is a partial cross-sectional view corresponding to FIG. 9, showing a state after the servo piston has been pushed in the direction of the first axis. 11 is a partial cross-sectional view of the axial piston device according to Embodiment 1 of the present invention, and is a partial cross-sectional view corresponding to FIG. 5 of Embodiment 1. FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. 11, corresponding to FIG. 6 of the first embodiment. FIG. 13 is a cross-sectional view corresponding to FIG. 12, showing a state in which the first valve shaft is operated in the first direction around the axis with respect to the second valve shaft. FIG. 14 is a partial cross-sectional view corresponding to FIG. 13, showing a state after the servo piston has been pushed in the direction of the first axis. FIG. 15 is a hydraulic circuit diagram of an axial piston device according to Embodiment 3 of the present invention. 16 is a partial cross-sectional view of the axial piston device according to the third embodiment, and is a partial cross-sectional view corresponding to FIG. 5 of the first embodiment. 17 is a cross-sectional view taken along line XVII-XVII in FIG. 16, corresponding to FIG. 6 of the first embodiment. FIG. 18 is an enlarged view of section XVIII in FIG. 17, and FIGS. 18(a) to 18(c) respectively show states in which the spool of the solenoid proportional valve is positioned at the initial position, protruded position and retracted position. there is

Embodiment 1
An embodiment of an axial piston device according to the present invention will be described below with reference to the accompanying drawings.
1 and 2 respectively show a hydraulic circuit diagram and a sectional view of an axial piston device 1A according to this embodiment.
3 and 4 show cross-sectional views taken along lines III-III and IV-IV in FIG. 2, respectively.
Furthermore, FIG. 5 shows an enlarged view of the V portion in FIG.
6 and 7 show cross-sectional views along lines VI-VI and VII-VII in FIG. 5, respectively.

As shown in FIGS. 1 to 7, the axial piston device 1A includes a housing 100, a first rotating shaft 30 (1) supported by the housing 100 so as to be rotatable around the axis, and the first rotating shaft 30 ( 1) and the first axial piston member 40 (1) accommodated in the housing 100 in a state of being supported so as not to rotate relative to the first axial piston member 40 (1), and the first axial piston member 40 (1) according to the tilt position about the swing axis. ), and a hydraulic servomechanism 500 for generating an operating force for tilting the first swash plate 50(1) about the swing axis. ing.

The axial piston device 1A according to the present embodiment is a hydraulic continuously variable transmission (hereinafter referred to as HST).
That is, the axial piston device 1A further includes a second rotary shaft 30(2) supported by the housing 100 so as to be rotatable around the axis, and a second rotary shaft 30(2) supported by the second rotary shaft 30(2) so as not to be relatively rotatable. and a second swash plate 50(2) that defines the volume of the second axial piston member 40(2).
Of course, the axial piston device according to the present invention is not limited to such a form, and can be applied to various forms such as a hydraulic pump device having a single or a plurality of hydraulic pumps.

In this embodiment, the first axial piston member 40(1) acts as a hydraulic pump, the second axial piston member 40(2) acts as a hydraulic motor, and the first and second axial piston members 40(2) The piston members 40(1), 40(2) are fluidly connected by a pair of first and second hydraulic fluid lines 200a, 200b.

The first rotating shaft 30(1) acts as a pump shaft, one end of which is operatively connectable to a drive source (not shown), and the second rotating shaft 30(2) has one end that extends outward. It acts as a motor shaft capable of outputting rotational power.
In this embodiment, the first and second rotation shafts 30(1), 30(2) are arranged parallel to each other.

As shown in FIGS. 1 and 2, the second swash plate 50(2) is of a fixed type, and the volume of the second axial piston member 40(2) acting as the hydraulic motor is fixed. .
Of course, it is also possible to make the second swash plate 50(2) movable.

The housing 100 is located on the side of the first rotating shaft 30(1) closer to the swash plate main body 55(1) of the first swash plate 50(1) than the first axial piston member 40(1). A first end wall portion 110 supporting the first end portion 31(1) so as to be rotatable around the axis, and a second end wall portion 110 of the first rotating shaft 30(1) opposite to the first end portion 31(1). It has a second end wall portion 112 that supports the end portion 32(1) so as to be rotatable around the axis, and a cylindrical peripheral wall portion 115 that connects the peripheral edges of the first and second end wall portions 110 and 112. ing.
In this embodiment, the second end 32(1) of the first rotating shaft 30(1) acts as an input end for operationally inputting rotational power from the drive source.

As described above, in the present embodiment, the second rotating shaft 30(2) is arranged parallel to the first rotating shaft 30(1).

Therefore, the first end portion 31(2) of the second rotating shaft 30(2) on the side closer to the second swash plate 50(2) than the second axial piston member 40(2) is the first end portion 31(2) of the second rotating shaft 30(2). The end wall portion 110 supports the second rotating shaft 30(2) so as to be rotatable around the axis. It is supported by the end wall portion 112 so as to be rotatable around the axis.
In this embodiment, the second end 32(2) of the first rotating shaft 30(1) acts as an output end for outputting the rotational power of the hydraulic motor.

In this embodiment, as shown in FIGS. 2 and 3, etc., the housing 100 integrally has the first end wall 110 and the peripheral wall portion 115, and the first end of the peripheral wall portion 115 is A case body 120 whose side opposite to the wall 110 has axial openings for allowing the first and second axial piston members 40(1) and 40(2) to pass therethrough; and a port block 130 that is detachably connected to the case body 120 to form the second end wall portion 112 .
The port block 130 is formed with a pair of first and second hydraulic fluid passages 210a, 210b forming the pair of first and second hydraulic fluid lines 200a, 200b.

The first axial piston member 40(1) is supported by the first rotating shaft 30(1) so as not to rotate relative thereto, and has a plurality of cylinder holes arranged around the axis of the first rotating shaft 30(1). a cylinder block 42(1) having a cylinder block 42(1), and a plurality of pistons which are housed in the plurality of cylinder holes so as to be freely advanceable and retractable, and whose free ends are engaged with the swash plate main body 55(1) of the first swash plate 50(1). 45(1).

The second axial piston member 40(2) has substantially the same configuration as the first axial piston member 40(1).
Therefore, the second axial piston member 40(2) is given the same reference numerals as the first axial piston member 40(1), with the suffix (1) changed to (2). omitted.

The cylinder block 42(1) is in contact with the port block 130 via a distribution valve plate at the end face opposite to the corresponding first swash plate 50(1) in the axial direction.

The cylinder hole has an opening on the side close to the corresponding first swash plate 50(1) that allows the piston 45(1) to move forward and backward. is fluidly connected to the pair of working oil passages 210a and 210b via the distribution valve plate on the opposite side with respect to the axial direction.

The first swash plate 50(1), which is a movable swash plate, includes a swash plate shaft 51(1) supported by the housing 100 so as to be rotatable about the swing axis, and a swash plate shaft 51(1). The swash plate main body 55(1) tilts about the rocking axis in accordance with the rotation about the axis, and the plurality of pistons 45(1) of the corresponding first axial piston member 40(1). The swash plate body 55(1) with which the free end is engaged.

As shown in FIG. 3 and the like, in this embodiment, a peripheral wall portion 115 of the housing 100 is provided with a bearing portion 116 for supporting the swash plate shaft 51(1). 51(1) is supported by the bearing portion 116 via a bearing 59 so as to be rotatable around the axis.

In the present embodiment, as shown in FIG. 3, the first swash plate 50(1) has a first swash plate shaft 51a on the side to which the tilting operation force is input as the swash plate shaft 51(1). (1), and a trunnion type swash plate having a second swash plate shaft 51b(1) extending across the swash plate body 55(1) in the opposite direction to the first swash plate shaft 51a(1). It is said that

Therefore, the peripheral wall portion 115 of the housing 100 has first and second bearing portions 116a as the bearing portion 116 for supporting the first and second swash plate shafts 51a(1) and 51b(1), respectively. , 116b are provided.

Of course, the present invention is not limited to such a form, and the back surface of the first swash plate 50 ( 1 ) opposite to the piston engagement surface is in sliding contact with the first end wall portion 110 . It is also possible to use a cradle-type swash plate that can be tilted about the swing axis in a state where the swash plate is tilted. In this case, the base end side of a connecting arm 520, which will be described later, is connected to one side surface of the cradle type swash plate so as not to rotate relative to the swing axis.

As shown in FIG. 3, the peripheral wall portion 115 of the housing 100 further includes at least the first and second swash plate shafts 51a(1) and 51b(1) of the first swash plate 50(1), A bearing portion (this In the embodiment, a first radial opening 117 is provided to open the first bearing portion 116 a ) outward, and the first radial opening 117 is a first radial opening detachably attached to the peripheral wall portion 115 . It is closed by a lid 140a.

In this embodiment, as shown in FIG. 3, in addition to the first radial opening 117a, the peripheral wall portion 115 of the housing 100 has the input side of the first swash plate 50(1). A bearing portion (the second bearing portion 116b in the present embodiment) for supporting a swash plate shaft other than the swash plate shaft (the second swash plate shaft 51b(1) in the present embodiment) is provided. A second radial opening 117b that opens outward is provided, and the second radial opening 117b is closed by a second cover 140b detachably attached to the peripheral wall portion 115. As shown in FIG.

As shown in FIGS. 1 and 2, etc., the axial piston device 1A according to the present embodiment further includes an auxiliary pump unit 60 including an auxiliary pump 62 rotationally driven by the first rotating shaft 30(1). are doing.

The auxiliary pump unit 60 further has an auxiliary pump case 65 connected to the housing 100 so as to surround the auxiliary pump 62 .

As shown in FIG. 2, in this embodiment, the first rotating shaft 30(1) has the first end 31(1) extending outward from the first end wall 110. The auxiliary pump 62 is supported by the outwardly extending portion of the first end portion 31(1) of the first rotating shaft 30(1) so as not to rotate relative thereto.

The auxiliary pump case 65 is connected to the first end wall portion 110 so as to surround the auxiliary pump 62 .
The auxiliary pump case 65 is provided with a suction oil passage 66 having one end open to the outer surface to form a suction port 66P and the other end fluidly connected to the suction side of the auxiliary pump 62; A discharge oil passage 67 is provided which is fluidly connected to the discharge side of the auxiliary pump 62 and whose other end opens to the outer surface to form a discharge port 67P.

As shown in FIGS. 1 and 2, the housing 100 includes, in addition to the pair of first and second hydraulic fluid passages 210a and 210b, a supply hydraulic fluid passage one end of which opens to the outer surface to form an inlet port 220P. An oil passage 220, a relief valve 225 for setting the hydraulic pressure of the supply oil passage 220, one end of which is fluidly connected to the supply oil passage 220, and branched into first and second branch oil passages 230a and 230b at a branch point 231. and the downstream ends of the first and second branched oil passages 230a and 230b in the pressure oil flow direction are fluidly connected to the first and second hydraulic oil passages 210a and 210b, respectively. The charge oil passage 230 and the first and second branch oil passages 230a, 230b are arranged to allow pressurized oil to flow from the supply oil passage 220 into the corresponding working oil passages 210a, 210b and prevent reverse flow. are provided with check valves 235 interposed respectively.

The inlet port 220</b>P is connected to the discharge port 67</b>P via an external pipe 222 , and pressurized oil from the auxiliary pump 62 is supplied to the supply oil passage 220 .

In this embodiment, a high-pressure relief valve 240 is inserted in parallel with the check valve 235 in each of the first and second branched oil passages 230a and 230b. The high-pressure relief valve 240 releases the pressure oil in one of the hydraulic fluid passages (for example, the first hydraulic fluid passage 210a) to the branch oil connected to the other hydraulic fluid passage 210b when the pressure in the one hydraulic fluid passage (for example, the first hydraulic fluid passage 210a) is abnormally high. Through the check valve 325 interposed in the passage 230b and the branch oil passage 230b, the oil is relieved to the other hydraulic passage 210b.

In addition, a bypass oil passage 250 that bypasses the check valve 235 inserted in the one branch oil passage and a bypass oil passage 250 that is inserted in the bypass oil passage 250 A diaphragm 252 is provided.

The bypass oil passage 250 and the throttle 252 are provided to prevent deterioration of the HST operating efficiency and ensure the HST neutral width. Preferably, the pair of first and second hydraulic oil passages 210a , 210b, it is provided in a branched oil passage (for example, the second branched oil passage 230b) fluidly connected to the hydraulic oil passage (for example, the second hydraulic oil passage 210b) on the high pressure side during reverse travel.

FIG. 8 shows an exploded perspective view of main constituent members of the hydraulic servomechanism 500 and the first swash plate 50(1).
As shown in FIGS. 1 to 8, the hydraulic servomechanism 500 includes a servo piston 510 reciprocatably accommodated in a servo space 505 formed in the housing 100, and the servo piston 510 connected to the first swash plate. and a connecting arm 520 for connecting to 50(1).

As shown in FIGS. 3, 5, and 7 to 8, the servo piston 510 liquid-tightly seals first and second oil chambers 506a and 506b at one longitudinal end and the other longitudinal end of the servo space 505, respectively. It is accommodated in the servo space 505 in a state of being divided into two, and is moved in the first axial direction by the supply of pressure oil to the first oil chamber 506a and the discharge of pressure oil from the second oil chamber 506b. By supplying pressure oil to the oil chamber 506b and discharging pressure oil from the first oil chamber 506a, it is moved in the direction of the second axis.

As shown in FIGS. 3 and 5, in the present embodiment, the servo space 505 is defined by the peripheral wall portion 115 near the region where the first radial opening 117a is provided and the first end wall portion. 110 is connected to the housing 100 so that the longitudinal direction thereof is perpendicular to both the axis of the first rotating shaft 30(1) and the oscillation axis.
With such a configuration, the servo space 505 can be formed while miniaturizing the housing 100 as much as possible.

As shown in FIGS. 3, 5, and 8, the connecting arm 520 causes the first swash plate 50(1) to swing in accordance with the movement of the servo piston 510 in the first and second axial directions. The servo piston 510 and the input side swash plate shaft (the first swash plate shaft 51a(1)) of the first swash plate 50(1) are connected so as to tilt about the axis in first and second directions. ing.

In this embodiment, as shown in FIGS. 7 and 8, the servo piston 510 is liquid-tight and slides on the inner peripheral surface of the servo space 505 with the end face facing the first oil chamber 506a. A first large-diameter portion 511a that is in contact with the first large-diameter portion 511a, and a second large-diameter portion 511a that is in liquid-tight and slidable contact with the inner peripheral surface of the servo space 505 with its end surface facing the second oil chamber 506b. It has a diameter portion 511b and a small diameter portion 513 located between the first and second large diameter portions 511a and 511b in the longitudinal direction.

In this embodiment, a neutral urging mechanism is provided to forcibly return the servo piston 510 to the neutral position when the oil pressure supply to the oil chambers 506a and 506b is cut off due to engine stop or the like. As shown in FIG. 7, in this embodiment, the servo piston 510 has a hollow cylindrical shape, and the hollow portion of the servo piston 510 accommodates a spring 510a forming the neutral biasing mechanism. The servo piston 510 is suspended in the servo space 505 from a support rod 510b attached to the housing 100 via the spring 510a.

The connecting arm 520 has a base end side which is not rotatable relative to the input side swash plate shaft (in this embodiment, the first swash plate shaft 51a(1)) of the first swash plate 55(1). The free end side is engaged with the small diameter portion 513 of the servo piston 510, so that the axial movement of the servo piston 510 moves the first swash plate 55(1) around the swing axis. It is designed to be tilted.

As shown in FIGS. 1 and 4, etc., the hydraulic servomechanism 500 is further fluidly connected to a pressure oil line 530 for receiving pressure oil from a hydraulic source, and to the first and second oil chambers 506a and 506b, respectively. Switching to switch connection states of the first and second supply/discharge lines 535a and 535b, the drain line 540, the pressure oil line 530, the first supply/discharge line 535a, the second supply/discharge line 535b, and the drain line 540 and a valve set 600A.

As shown in FIGS. 4 to 6 and 8, the switching valve set 600A includes a first valve shaft 610A housed in an installation hole 105 formed in the housing 100 so as to be liquid-tight and rotatable around the axis; and a second valve shaft 620A that is rotatably accommodated in the inner shaft hole of the first valve shaft 610A.

In this embodiment, as shown in FIGS. 4 and 5, the installation hole 105 is formed in the first cover 140a so that the axial direction thereof is parallel to the swing axis. The set 600A is attached to the first lid 140a.

One of the first and second valve stems 610A, 610B acts as an input valve stem and the other of the first and second valve stems 610A, 610B acts as a feedback valve stem.
Details of the switching valve set 600A will be described later.

The pressure oil line 530 is configured to guide pressure oil received from a hydraulic source to the inflow port 106 of the installation hole 105 .
As shown in FIGS. 1 and 4 to 6, in this embodiment, the pressure oil line 530 has one end fluidly connected to the supply oil passage 220 and the other end fluidly connected to the inflow port 106. It has a pressure oil passage 532 formed in the housing 100 for connection. Specifically, in this embodiment, the pressure oil passage 532 is formed in the case body 120, the port block 130 and the first lid body 140a.

In this embodiment, the first and second supply/discharge lines 535a and 535b have first and second supply/discharge oil passages 537a and 537b formed in the housing 100, respectively.

Specifically, as shown in FIGS. 6 and 7, the first oil supply/drainage passage 537a has one end fluidly connected to the first connection port 107a of the installation hole 105 and the other end connected to the first oil chamber. It is formed over the case body 120 and the first lid body 140a so as to be fluidly connected to 506a.
The second oil supply/drainage passage 537b has one end fluidly connected to the second connection port 17b of the installation hole 105 and the other end fluidly connected to the second oil chamber 506b. It is formed over the first lid 140a.

In this embodiment, the drain line 540 has a drain oil passage 542 formed in the second valve shaft 620A.
As shown in FIGS. 5 and 6, the drain oil passage 542 has an inlet end that opens to the outer surface of the second valve shaft 520A and an outlet end that extends through the housing 100 through the first radial opening 117a. open to the interior space of

Further, the hydraulic servomechanism 500 moves the feedback valve shaft (in this embodiment, the first valve shaft 610A) to the input valve shaft (in this embodiment, the It has a feedback arm 550 that rotates about the axis relative to the second valve shaft.

As shown in FIGS. 5 and 8, etc., in the present embodiment, the feedback arm 550 has a proximal end that is located at the inner end of the feedback valve shaft (in the present embodiment, the first valve shaft 610A). The free end extends outward in the radial direction of the feedback valve shaft (the first valve shaft 610A) while being connected so as not to rotate relative to each other about the axis.

Further, the feedback arm 550 and the connecting arm 520 are operatively connected via a concave-convex structure 560 that can be engaged and disengaged with the peripheral wall portion 115 of the first cover 140a.

Specifically, as shown in FIGS. 5 and 8, the concave-convex structure 560 is positioned at an intermediate portion between the base end side and the free end side of the connecting arm 520 so as to align the axis of the first rotating shaft 30(1). The feedback arm 550 has a convex portion 562 that protrudes outward with respect to a reference radial direction, and a concave portion (opening) 564 that is provided so that the convex portion 562 can be engaged in the feedback arm 550 . ing.

With such a configuration, the switching valve set 600A and the feedback arm 550 are attached to the housing 100 to which the first swash plate 50(1), the connecting arm 520 and the servo piston 510 are attached. By mounting the first lid body 140a in the folded state, the engagement state of the connection arm 520 and the feedback arm 550 can be revealed.
Therefore, it is possible to improve the efficiency of the assembly work of the axial piston device 1A.

It should be noted that, of course, a convex portion (not shown) provided on the feedback 550 so that the concave-convex structure 560 protrudes radially inward with respect to the axis of the first rotating shaft 30(1). and a concave portion (opening) (not shown) provided in the connecting arm 520 so that the convex portion can be engaged.

Here, the detailed configuration of the switching valve set 600A will be described.
As shown in FIG. 6 and described above, the installation hole 105 into which the first valve shaft 610A is inserted is provided with the inflow port 106 and the first and second connection ports 107a and 107b. .

On the other hand, on the first valve shaft 610A, the inflow port 106, the first connection port 107a and the second connection port 107b are communicated with the inner axial holes of the first valve shaft 610a at different positions in the circumferential direction. An inflow opening 611, a first connection opening 612a and a second connection opening 612b are provided to allow the flow of air.
In addition, in the present embodiment, as shown in FIG. 6, the inflow openings 611 are provided at two different locations in the circumferential direction.

As shown in FIG. 6, the second valve shaft 620A inserted into the first valve shaft 610A has a drain region 621 in which the inlet end of the drain oil passage 542 is opened at different positions in the circumferential direction. , an oil passage region 622 that can selectively fluidly connect the inflow port 106 to the first or second connection ports 107a, 107b; Second closed regions 623a, 623b are provided.

In this embodiment, the second valve shaft 620A acts as an input valve shaft for inputting the tilting operation force, and the first valve shaft 610A acts as a feedback valve shaft.

Specifically, as shown in FIG. 5 and the like, the first valve shaft 610A acting as the feedback valve shaft is a cylindrical shaft having the internal axis line hole as a through hole, and the first valve shaft 610A acting as the input valve shaft is a cylindrical shaft. The second valve shaft 620A has an outer end extending outward while being inserted into the first valve shaft 610A to form an outward extending portion 628A. forms an operation input unit that can be operated manually.

FIG. 6 shows that the second valve shaft 620A acting as the input valve shaft is positioned at a reference position around the axis (for example, a neutral position where the HST is in a neutral state) and the first swash plate 50(1). is located at a reference position around the swing axis (for example, a neutral position that brings out the neutral state of the HST).

As shown in FIG. 6, when the second valve shaft 620A and the first swash plate 50(1) are positioned at the reference position, the first and second closed areas 623a and 623b are closed to the first closed area, respectively. 1 and second connection ports 107a, 107b are closed, thereby holding the first swash plate 50(1) at the reference position.

9 is a partial cross-sectional view corresponding to FIG. 6, in which the second valve shaft 620A is operated in the first direction (counterclockwise direction in FIG. 9) around the axis with respect to the first valve shaft 610A. Fig. 3 shows a partial cross-sectional view of the state;

As shown in FIG. 9, when the second valve shaft 620A is rotated about the axis in the first direction by a predetermined amount due to the tilting operation force, the inflow port 106 is moved through the oil passage region 622 to the first and second valve shafts. It is fluidly connected only to the first connection port 17a, which is the corresponding one of the second connection ports 107a, 107b, and through the drain area 621, of the first and second connection ports 107a, 107b. The other second connection port 107 b is fluidly connected to the inlet end of the drain oil passage 542 .

As a result, the servo piston 510 is pushed in the corresponding first axial direction, and the first swash plate 50(1) is tilted in the first direction about the corresponding swing axis.
9 shows a state immediately before the servo piston 510 is pushed in the direction of the first axis.

FIG. 10 is a partial cross-sectional view corresponding to FIG. 9, showing a state after the servo piston 510 has been pushed in the first axial direction.
When the servo piston 510 is moved in the first axial direction by a predetermined amount, the first swash plate 50(1) is rotated in the first direction about the corresponding swing axis by a predetermined amount.

At this time, the first valve shaft 610A moves relative to the second valve shaft 620A via the connecting arm 520 and the feedback arm 550 in accordance with the movement of the servo piston 510 in the first axial direction. is rotated in a corresponding direction (counterclockwise direction in FIG. 10) about the axis.

As a result, as shown in FIG. 10, the first and second connection ports 107a and 107b are blocked by the first and second blocking regions 623a and 623b, respectively, and the servo piston 510 moves in the axial direction at that time. A holding state appears in which the first swash plate 50(1) is held in position and the first swash plate 50(1) is held in the position at that time about the swing axis.

The hydraulic servo mechanism 500 having the switching valve set 600A having such a configuration can be made smaller and simpler than the conventional configuration, and the cost of the axial piston device 1A can be reduced. can.

In this embodiment, as shown in FIGS. 6 and 8 to 10, the first valve shaft 610A is positioned between the first and second connection openings 612a and 612b in the circumferential direction, 1 and the second connection ports 107a and 107b, an intermediate arc region 615 that can be in liquid-tight slidable contact with the inner peripheral surface of the installation hole 105, and the first connection opening 612a from the intermediate arc region 615 in the circumferential direction. a first arcuate region 616a extending toward the side close to the inflow opening 611 through the first connection port 612a and the inflow port 611 and capable of liquid-tightly slidably contacting the inner peripheral surface of the installation hole 105; With respect to the circumferential direction, it extends from the intermediate arc region 615 to the side close to the inflow opening 611 through the second connection opening 612b, and extends from the inner circumference of the installation hole 105 between the second connection port 612b and the inflow port 611. It has a second arcuate region 616b that can slidably contact the surface in a liquid-tight manner.
With such a configuration, it is possible to stabilize the movement of the first valve shaft 610A around the axis.

The axial piston device 1A according to the present embodiment further includes a reference position biasing mechanism 650 that biases the input valve shaft (the second valve shaft 620A in the present embodiment) toward the reference position around the axis. I have it.

The reference position around the axis of the input valve shaft is, for example, a neutral position that causes the HST to appear in a neutral state.

As shown in FIGS. 5, 6, and 8 to 9, the reference position biasing mechanism 650 is connected to the second valve shaft 620A at the base end thereof so as not to rotate relative to the axis. A reference position arm 655 extending in a direction perpendicular to the axis of shaft 620A, an engagement pin 660 erected on the reference position arm 655 so as to be parallel to the swing axis, and a longitudinal direction perpendicular to the swing axis. A reference position piston 670 is accommodated in an accommodation space formed in the first lid body 140a so as to reciprocate longitudinally, and the free end of the engagement pin 660 is engaged with the reference position piston 670, and the second valve shaft 620A. and a reference position biasing member 665 for biasing the reference position piston 670 toward a longitudinal reference position corresponding to the reference position about the axis of .

In this embodiment, as shown in FIG. 5 and the like, the second valve shaft 620A has an inner end extending outward from the axial hole of the first valve shaft 610A, and the reference position arm The proximal end of 655 is connected to the inner end of the second valve shaft 620A so as not to rotate relative to it.

In this embodiment, as shown in FIG. 6 and the like, the first lid body 140a is formed with a cavity 147 whose longitudinal direction is perpendicular to the swing axis and whose both ends are open. Openings on one side and the other side in the longitudinal direction of 147 are closed by first and second caps 148a and 148b, respectively.
A space defined by the cavity 147 and the first and second caps 148a and 148b forms the accommodation space.

The reference position piston 670 has first and second large-diameter portions 672a and 672b that are positioned on one side and the other side in the longitudinal direction, respectively, and liquid-tightly and slidably contact the inner peripheral surface of the accommodation space. , and a small diameter portion 674 positioned between the first and second large diameter portions 672a and 672b in the longitudinal direction, and a first cap 148a between the end face of the first large diameter portion 672a and the first cap 148a. The first input chamber 145a is defined, and the second input chamber 145b is defined between the end surface of the second large diameter portion 672b and the second cap 148b, and is accommodated in the accommodation space so as to reciprocate in the longitudinal direction. . Each of the input chambers 145a and 145b is always open to the inner space of the housing 100 through the first radial opening 117a through a drain hole (not shown) provided in the first cover 140a.

The free end of the engagement pin 660 is engaged in an engagement groove defined by the reduced diameter portion 674 such that longitudinal movement of the reference position piston 670 is responsive to the engagement pin 660 and the reference. Through the position arm 655, the second valve shaft 620A rotates around the axis.

The first and second input chambers 145a and 145b are provided with first and second position adjustment bolts 680a and 680b, respectively, whose fixing positions in the longitudinal direction can be changed.
The first and second position adjusting bolts 680a and 680b have the same construction.
Therefore, in the figure, the second position adjusting bolt 680b is given the same reference numeral as the first position adjusting bolt 680a with the suffix changed to b, and the description thereof will be omitted as appropriate.

Specifically, the first position adjusting bolt 680a has a threaded portion at its outer end that is screwed into the first cap 148a, and has a large-diameter head 682a at its inner end. The longitudinal fixed position is changed according to the rotation.
Reference numeral 684a in the drawing denotes a fixing nut that is screwed onto the threaded portion of the first position adjusting bolt 980a to fix the longitudinal position of the first position adjusting bolt 680a.

A first outer spring bearing 690a is provided on the outer end side of the portion of the first position adjusting bolt 680a located in the first input chamber 145a so as not to move relative to the longitudinal direction, and the first position adjusting bolt A first inner spring receiving member 692a is provided on the inner end side of 680a so as to be relatively movable in the longitudinal direction.
The first inner spring bearing member 692a is engaged with the head portion 682a of the first position adjusting bolt 680a, thereby forming an end of movement to the inner end side.

The reference position biasing member 665 includes a first reference position biasing member 665a inserted in a compressed state between the first inner spring receiving member 692a and the first outer spring receiving member 690a, and a second inner spring. and a second reference position biasing member 665b interposed in a compressed state between the receiving member 692b and the second outer spring receiving member 690b.

The first large-diameter portion 672a of the reference position piston 670 has a first outer axial hole having an inner diameter that allows the first inner spring bearing member 692a to be inserted thereinto, and a first step from the first outer axial hole. A first inner axial hole extending axially inward in a reduced diameter state is provided.

The first inner axial hole has an inner diameter that allows insertion of the head portion 682a of the first position adjusting bolt 680a but prevents insertion of the first inner spring bearing member 692a.

Here, when the reference position piston 670 is positioned at the longitudinal reference position corresponding to the reference position around the axis of the second valve shaft 620A acting as the input valve shaft, the first reference position urging member The first inner spring bearing member 692a urged toward the second oil chamber 145b by 665a engages both the head portion 682a and the first stepped portion of the first position adjustment bolt 680a and The second inner spring receiving member 692b, which is biased toward the first oil chamber 145a by the second reference position biasing member 665b, is positioned on both the head portion 682b of the second position adjusting bolt 680b and the second stepped portion. The longitudinal positions of the first and second position adjustment bolts 680a, 680b are set so as to engage with the .

Therefore, although the first axial piston member 40(1) is actuated by the rotational drive of the first rotary shaft 30(1), the second valve shaft 620A does not have a tilting operation force around the axis. In the non-operated state in which the load is not applied, the reference position piston 670 is clamped and fixed by the first and second reference position urging members 665a and 665b to be positioned at the axial reference position and the second reference position. The valve shaft 620A is held at a reference position (for example, a neutral position) around the axis, whereby the pressure on the suction side and the pressure on the discharge side of the first axial piston member 40(1) have a predetermined difference in a reference state (this embodiment). In the form of (1), a neutral state in which the difference between the suction side pressure and the discharge side pressure is zero is maintained.

On the other hand, when an operating force is applied to the second valve shaft 620A to rotate the second valve shaft 620A from the reference position about the axis to one side about the axis, the reference position piston 670 moves to the first position. and the corresponding one of the second reference position biasing members 665a and 665b is compressed and pushed in the corresponding longitudinal direction.

At this time, the head (682a) of the position adjustment bolt (for example, the first position adjustment bolt 680a) on the side of one of the compressed biasing members (for example, the first reference position biasing member 665a) moves toward the reference position piston ( It penetrates into the inner axial hole of the first position adjusting bolt 680a).

Then, when the operating force applied to the second valve shaft 620A is released, the reference position piston 670 moves the biasing member (for example, the first reference position biasing member) compressed by the longitudinal movement of the reference position piston 670. By the biasing force of the member 665a), it is returned to the axial reference position and is held in the axial reference position by the first and second reference position biasing members 665a, 665b.

Embodiment 2
Another embodiment of the axial piston device according to the present invention will be described below with reference to the accompanying drawings.
FIG. 11 shows a partial cross-sectional view of an axial piston device 1B according to the present embodiment, which corresponds to FIG. 5 in the first embodiment.
12 shows a cross-sectional view taken along line XII-XII in FIG. 11 and corresponding to FIG. 6 of the first embodiment.
In the drawings, the same reference numerals are given to the same members as in the first embodiment, and the description thereof will be omitted as appropriate.

Unlike the axial piston device 1A according to the first embodiment, the axial piston device 1B according to the present embodiment has a switching valve set 600B instead of the switching valve set 600A.

The switching valve set 600B includes a first valve shaft 610B housed in the installation hole 105 so as to be liquid-tight and rotatable around the axis, and a first valve shaft 610B housed in the inner axis hole of the first valve shaft 610B so as to be rotatable around the axis. The first valve shaft 610B acts as an input valve shaft rotated around the axis by the tilting operation force, and the second valve shaft 620B acts as a feedback valve shaft. there is

More specifically, as shown in FIG. 11, the axial hole of the first valve shaft 610B opens to the inner end surface. The outer end of the first valve stem 610B extends outward from the housing 100 (the first lid 140a) to form an outwardly extending portion 618B. 618B forms an operation input unit that can be operated manually.

One end of the second valve shaft 620B extends outward (inwardly of the housing 100) from the axial hole of the first valve shaft 610B and extends around the axial hole. It is rotatably interpolated.

In this embodiment, the base end side of the feedback arm 550 is connected to the inner end side of the extension portion of the second valve shaft 620B so as not to rotate relative to the axis.
The base end side of the reference position arm 655 is connected to the inner end side of the first valve shaft 610B so as not to rotate relative to the axis.

The switching valve set 600B operates as follows.
FIG. 12 shows that the first valve shaft 610B acting as the input valve shaft is positioned at a reference position around the axis (for example, a neutral position where the HST is in a neutral state) and the first swash plate 50(1) is positioned. is located at a reference position around the swing axis (for example, a neutral position that brings out the neutral state of the HST).

As shown in FIG. 12, when the first valve shaft 610B and the first swash plate 50(1) are positioned at the reference position, the first and second closed regions 623a and 623b are closed to the first 1 and second connection ports 107a, 107b are closed, thereby holding the first swash plate 50(1) at the reference position.

FIG. 13 shows a partial cross-sectional view of a state in which the first valve shaft 610B is operated in the first direction (counterclockwise direction in FIG. 13) around the axis with respect to the second valve shaft 620B.

As shown in FIG. 13, when the first valve shaft 610B is rotated about the axis in the first direction by a predetermined amount due to the tilting operation force, the inflow port 106 is moved through the oil passage region 622 to the first and the first valve shafts. Only the first connection port 107a, which is one of the second connection ports 107a and 107b, is fluidly connected to supply pressure oil to the first oil chamber 506a, and through the drain area 621, the A second connection port 107b, which is the other one of the first and second connection ports 107a and 107b, is fluidly connected to the inlet end of the drain oil passage 542 to discharge pressure oil from the second oil chamber 506b.

As a result, the servo piston 510 is pushed in the corresponding first axial direction, and the first swash plate 50(1) is tilted in the first direction about the corresponding swing axis.
13 shows a state immediately before the servo piston 510 is pushed in the direction of the first axis.

FIG. 14 shows a partial cross-sectional view of the state after the servo piston 510 has been pushed in the direction of the first axis.
When the servo piston 510 is moved in the first axial direction by a predetermined amount, the first swash plate 50(1) is rotated in the first direction about the corresponding swing axis by a predetermined amount.

At this time, the second valve shaft 620B moves relative to the first valve shaft 610B via the connecting arm 520 and the feedback arm 550 in accordance with the movement of the servo piston 510 in the first axial direction. is rotated in a corresponding direction (counterclockwise direction in FIG. 14) about the axis.

As a result, as shown in FIG. 14, the first and second connection ports 107a and 107b are blocked by the first and second blocking regions 623a and 623b, respectively, and the servo piston 510 moves axially at that point. A holding state appears in which the first swash plate 50(1) is held in position and the first swash plate 50(1) is held in the position at that time about the swing axis.

In the axial piston device 1B having the switching valve set 600B having such a configuration, the same effect as in the first embodiment can be obtained.

Embodiment 3
Another embodiment of the axial piston device according to the present invention will be described below with reference to the accompanying drawings.
FIG. 15 shows a hydraulic circuit diagram of the axial piston device 1C according to this embodiment.
Further, FIG. 16 shows a partial cross-sectional view of an axial piston device 1C according to the present embodiment, which corresponds to FIG. 5 in the first embodiment.
Further, FIG. 17 shows a cross-sectional view taken along line XVII-XVII in FIG. 16 and corresponding to FIG. 6 of the first embodiment.
In the drawings, the same members as those in Embodiments 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

In Embodiments 1 and 2, among the first and second valve shafts 610A (610B) and 620A (620B), the valve shaft acting as the input valve shaft (in Embodiment 1, the second valve shaft The outer end portion of the shaft 620A (the first valve shaft 610B in the second embodiment) forms an operation input portion that can be manually operated.

On the other hand, in the axial piston device 1C according to the present embodiment, the input valve shaft is rotated around the axis using hydraulic pressure.

Specifically, the axial piston device 1C has a switching valve set 600C in place of the switching valve set 600A, and furthermore has an operating member 710 that is manually operated, and the operating member 710. 710, a hydraulic operating mechanism 750 that rotates the input valve shaft about its axis, and a control device 700 that controls the operation of the hydraulic operating mechanism 750.

The switching valve set 600C differs from the switching valve set 600A in the first embodiment only in that the second valve shaft 620C acting as an input valve shaft does not have an operation input portion that can be operated manually. .

Specifically, the switching valve set 600C includes the first valve shaft 610A that is liquid-tightly and axially rotatably accommodated in the installation hole 105, and the first valve shaft 610A that is internally rotatable about the axis. A second valve stem 620C is removably accommodated such that the second valve stem 620C acts as an input valve stem for inputting a swash plate operating force and the first valve stem 620A acts as a feedback valve stem. is configured to

The second valve shaft 620C differs from the second valve shaft 620A only in that it does not have the outer end extension portion 628A.
Reference numeral 629C in FIG. 16 denotes an engaging recess for manually operating the second valve shaft 620C acting as an input valve shaft in the event of failure of the hydraulic operation mechanism 750, and has a rectangular cross-sectional shape. etc. is assumed to be non-circular.

As shown in FIGS. 15 to 17, the hydraulic operation mechanism 750 extends in a direction orthogonal to the second valve shaft 620C while its proximal end is connected to the second valve shaft 620C so as not to rotate relative to the axis. First and second operating oil chambers 155a and 155b are liquid-tightly arranged at one end and the other end of the housing space formed in the housing 100 so that the operating arm 755 is perpendicular to the swing axis. It is housed in the housing space in a state of being divided into two, and is moved in the first longitudinal direction by pressure oil supply to the first operation oil chamber 155a and pressure oil discharge from the second operation oil chamber 155b, and the second operation oil chamber 155b. Operation piston 770 moved in the second longitudinal direction by the supply of pressure oil to the oil chamber 155b and the discharge of pressure oil from the first operation oil chamber 155a, and the movement of the operation piston 770 in the first and second longitudinal directions a connecting member 760 that operatively connects the operating piston 770 and the operating arm 755 so that the second valve shaft 620C acting as the input valve shaft rotates about the axis in first and second directions, respectively, according to , first and second operation biasing members 765a and 765b respectively arranged in the first and second operation oil chambers 155a and 155b so as to press the operation piston 770, and an operation for receiving pressure oil from a hydraulic source. It has a pressure oil line 800, an operation drain line 810, and first and second electromagnetic proportional valves 820a, 820b for switching supply and discharge of pressure oil to the first and second operation oil chambers 155a, 155b, respectively.

In the present embodiment, the accommodation space for accommodating the operation piston 770 is formed in the first lid body 140a, similarly to the accommodation space for accommodating the reference position piston 670. As shown in FIG.
Specifically, as shown in FIG. 17, the first lid 140a is formed with a cavity 157 whose longitudinal direction is perpendicular to the swing axis and whose both ends are open. The side and other side openings are closed by first and second caps 158a, respectively.
the cavity 157 and the first and second caps 158a; The space defined by 158b forms the receiving space.

The operating piston 77 has first and second large diameter portions 772a and 772b, which are positioned on one side and the other side in the longitudinal direction, respectively, and liquid-tightly and slidably contact the inner peripheral surface of the housing space, and a small diameter portion 774 located between the first and second large diameter portions 772a and 772b in the longitudinal direction, and the first cap 158a between the end surface of the first large diameter portion 772a and the first cap 158a. 1 operation oil chamber 155a is defined, and the second operation oil chamber 155b is defined between the end face of the second large diameter portion 772b and the second cap 158b, and is accommodated in the accommodation space so as to reciprocate in the longitudinal direction. It is

In the present embodiment, the connecting member 760 is erected on the operating arm 755 so as to be parallel to the swing axis, and the free end is engaged with the small diameter portion 774 of the operating piston 770 . An engagement pin is engaged with the groove.

In the present embodiment, as shown in FIG. 17, the hydraulic operation mechanism 750 further includes first and second hydraulic pressure chambers 155a and 115b arranged in the first and second hydraulic chambers 155a and 115b so as to be able to change fixed positions in the longitudinal direction. and second position adjusting bolts 780a and 780b.

The first and second position adjusting bolts 780a and 780b have the same construction.
Therefore, in the figure, the second position adjusting bolt 780b is given the same reference numeral as the first position adjusting bolt 780a with the suffix changed to b, and the description thereof will be omitted as appropriate.

Specifically, the first position adjusting bolt 780a has a threaded portion at its outer end that is screwed into the first cap 158a and has a large-diameter head 782a at its inner end. The longitudinal fixed position is changed according to the rotation.
Reference numeral 784a in the drawing denotes a fixing nut that is screwed onto the screw portion of the first position adjusting bolt 780a to fix the longitudinal position of the first position adjusting bolt 780a.

A first outer spring bearing 790a is provided on the outer end side of the portion of the first position adjusting bolt 780a located in the first operating oil chamber 155a so as not to move relative to the first position adjusting bolt 780a. A first inner spring bearing member 792a is provided on the inner end side of the bolt 780a so as to be relatively movable in the longitudinal direction.
The first inner spring receiving member 792a is engaged with the head portion 782a of the first position adjusting bolt 780a, thereby forming an end of movement toward the inner end side.

The first operation biasing member 765a is inserted between the first inner spring receiving member 792a and the first outer spring receiving member 790a in a compressed state, and the second operation biasing member 765b is inserted between the second spring receiving member 792a and the first outer spring receiving member 790a. It is interposed in a compressed state between the inner spring receiving member 792b and the second outer spring receiving member 790b.

The first large-diameter portion 772a of the operating piston 770 has a first outer axial hole having an inner diameter that allows the insertion of the first inner spring receiving member 792a, and a first stepped portion that is contracted from the first outer axial hole. A first inner axial bore is provided which extends axially inward in a diameterd state.

The first inner axial hole has an inner diameter that allows insertion of the head portion 782a of the first position adjusting bolt 780a but prevents insertion of the first inner spring bearing member 792a.

Here, when the operation piston 770 is positioned at the longitudinal reference position corresponding to the reference position around the axis of the second valve shaft 620C acting as the input valve shaft, the first operation biasing member 765a The first inner spring receiving member 792a biased toward the second operating oil chamber 155a engages both the head portion 782a and the first stepped portion of the first position adjusting bolt 780a, The second inner spring receiving member 792b, which is biased toward the first operation oil chamber 155a by the second operation biasing member 765b, engages both the head portion 782b and the second stepped portion of the second position adjustment bolt 780b. The longitudinal positions of the first and second position adjusting bolts 780a and 780b are set so as to engage with the .

Therefore, when pressure oil is not supplied to the first and second operation oil chambers 155a and 155b, the operation piston 770 is pressed by the first and second operation biasing members 765a and 765b. As a result, the second valve shaft 620C is held at the axial reference position (for example, the neutral position).

18(a) to (c) show enlarged views of XVIII in FIG.
As shown in FIGS. 17 and 18(a) to (c), the first electromagnetic proportional valve 820a has a main body 825 having a driving portion and an initial position, a projecting position and a retracted position in the axial direction. and a spool 830 housed in the main body 825 so as to be able to advance and retreat in the axial direction.

18(a)-(c) respectively show the spool 830 in the initial position, the extended position and the retracted position.
The second electromagnetic proportional valve 820b has the same configuration as the first electromagnetic proportional valve 820a. Therefore, the description of the first proportional solenoid valve 820a also applies to the second proportional solenoid valve 820b.

In the present embodiment, when the spool 830 is positioned at the projecting position, the initial position, and the retracted position, the corresponding first operating oil chambers 155a are cut off from the operating drain line 810, respectively. In the pressure oil supply state connected to the operation pressure oil line 800 (see FIG. 18(b)), the corresponding first operation oil chamber 155a blocks both the operation pressure oil line 800 and the operation drain line 810. (see FIG. 18(a)), and a pressurized oil discharge state in which the corresponding first operation oil chamber 155a is disconnected from the operation pressure oil line 800 and connected to the operation drain line 810. (see FIG. 18(c)) appears.

The drive unit can take an ON state in which the spool 830 is forcibly pushed in the projecting direction and positioned at the projecting position, and an OFF state in which the spool 830 is not substantially applied with a pushing force. It is configured.

In addition, in the present embodiment, as shown in FIGS. 18(a) to 18(c), the driving portions of the first and second proportional solenoid valves 820a and 820b are driven by the spool 830 in the ON state. It has a pin 827 that contacts the end face and pushes the spool 830 in the protruding direction.

In the present embodiment, a gap L is formed between the base end surface of the spool 830 and the tip end surface of the pin 827 facing each other. Depending on the relative hydraulic pressure difference between the chamber 155a and the operating drain line 810, it is configured to assume an initial position or a retracted position.

Specifically, as shown in FIGS. 18(a) to 18(c), the spool 830 receives the pressure of the corresponding first operation oil chamber 155a and pushes the spool 830 in the retracting direction. and the axial position of the spool 830 (initial position (Fig. 18(a)), retracted position (Fig. 18(c)) and projecting position (Fig. 18(b))). Accordingly, the corresponding first operating oil chamber 155 a is selectively closed, connected to the operating pressure oil line 800 , and has an oil hole 832 to connect to the operating drain line 810 .

That is, when the driving portion is in the ON state, the spool 830 is forcibly positioned at the projecting position (FIG. 18(b)) by performing a predetermined stroke of the gap L+α by the pushing force from the pin 827. When the drive unit is in the OFF state, the pressure in the first operation oil chamber 155a is zero and when the operation drain line 810 is in equilibrium, the initial position (FIG. 18(a)) is taken and the retraction direction is pushed. It assumes the retracted position (FIG. 18(c)) when the oil chamber hydraulic pressure is generated when the power exceeds the pressure (zero) in the operation drain line 810 .

The control device 700 controls the second valve shaft 620C so that the second valve shaft 620C acting as the input valve shaft is located at a position around the axis according to the operating state of the operating member 710 (signal from the operating sensor 715). 1 and 2nd electromagnetic proportional valves 820a and 820b.

That is, when the operating member 710 is operated by a predetermined amount in the first operating direction, the control device 700 moves the operating piston 770 by a predetermined amount in the corresponding first longitudinal direction. The first electromagnetic proportional valve 820a is turned on and the second electromagnetic proportional valve is turned off.

As a result, pressure oil is supplied from the operation pressure oil line 800 to the corresponding first operation oil chamber 155a, and the operation piston 770 moves in the first longitudinal direction.

At this time, the second operating oil chamber 155b is compressed by the movement of the operating piston 770 in the first longitudinal direction, the hydraulic pressure in the second operating oil chamber 155b increases, and the second operating oil chamber 155b is closed. Hydraulic pressure is generated.

Due to the increase in hydraulic pressure in the second operating oil chamber 155b, the spool 830 of the second electromagnetic proportional valve 820b, whose driving portion is in the OFF state, is pushed from the initial position to the retracted position, and the second operating oil chamber 155b is pushed. of pressure oil is discharged to the operation drain line 810 .

Accordingly, when the operating member 710 is operated in the first operating direction, the operating piston 770 moves in the first longitudinal direction by a predetermined amount, thereby moving through the operating arm 755 and the connecting member 760. The second valve shaft 620C acting as the input valve shaft is rotated by a predetermined angle in the corresponding direction about the axis. On the other hand, when the operating member 710 is operated in the second operating direction, the operating piston 770 moves in the second longitudinal direction by a predetermined amount, and the second valve shaft 620C rotates in the opposite direction corresponding to the rotation of the axis. rotated by an angle.

Further, the hydraulic operation mechanism 750 moves the second valve shaft 620C to a reference position (for example, neutral position).

Also in the axial piston device 1C having such a configuration, the same effects as in the first and second embodiments can be obtained.

Preferably, when the operating member 710 is neutral, the tip surface of the pin 827 and A weak electric current is applied to the driving portion so that the contact state of the proximal end surface of the spool 830 is maintained, and the pin 827 is lightly biased toward the proximal end surface of the spool 830 so that the gap L disappears. can do.

According to such a configuration, it is possible to improve the responsiveness of the spool 830 from the initial position to the projecting position when the drive unit is switched from the OFF state to the ON state.

In the present embodiment, the second valve shaft 620C is used as the input valve shaft and the first valve shaft 620A is used as the feedback valve shaft. Alternatively, the first valve stem may be the input valve stem and the second valve stem may be the feedback valve stem.

1A to 1C Axial piston device 30 (1) First rotating shaft 40 (1) First axial piston member 50 (1) First swash plate (movable swash plate)
100 housing 105 installation hole 106 inflow ports 107a, 107b first and second connection ports 110 first end wall portion 112 second end wall portion 115 peripheral wall portions 116a, 116b first and second bearing portions 117a, 117b first and second Two radial openings 120 Case body 130 Port blocks 140a, 140b First and second lid bodies 155a, 155b First and second operating oil chambers 500 Hydraulic servomechanism 505 Servo spaces 506a, 506b First and second oil chambers 510 Servo Piston 520 Connection arm 530 Pressure oil lines 535a, 535b First and second supply/discharge lines 540 Drain line 542 Drain oil passage 550 Feedback arm 560 Uneven structure 600A to 600C Switching valve set 610A, 610B First valve shaft 611 Inflow opening 612a, 612b first and second connection openings 615 intermediate arc regions 616a, 616b first and second arc regions 620A-620C second valve stem 621 drain regions 623a, 623b first and second closed regions 650 reference position biasing member 655 reference Position arm 660 Engaging pin 670 Reference position pistons 665a, 665b First and second reference position biasing member 700 Control device 710 Operation member 715 Operation sensor 750 Hydraulic operation mechanism 755 Operation arm 760 Connecting member 765a, 765b First and second Operation biasing member 770 Operation piston 800 Operation pressure oil line 810 Operation drain line 820a, 820b First and second electromagnetic proportional valves 825 Body 827 Pin 830 Spool 831 Oil chamber side pressure receiving portion

Claims (14)

a housing; a rotating shaft supported by the housing so as to be rotatable around an axis; an axial piston member accommodated in the housing while being supported by the rotating shaft so as not to rotate relative to the rotating shaft; an axial piston device comprising: a movable swash plate that changes the volume of the axial piston member in response to the movement of the axial piston member;
The hydraulic servomechanism is accommodated in a state in which first and second oil chambers are liquid-tightly divided at one end and the other end in the longitudinal direction of a servo space formed in the housing, and the hydraulic servomechanism is connected to the first oil chamber. It is moved in the direction of the first axis by the supply of pressure oil and discharge of pressure oil from the second oil chamber, and in the direction of the second axis by the supply of pressure oil to the second oil chamber and discharge of pressure oil from the first oil chamber. a servo piston to be moved; a connecting arm for tilting the movable swash plate in first and second directions about a swing axis according to the movement of the servo piston in first and second axial directions; and a hydraulic power source. a pressure oil line receiving pressure oil from, first and second supply/discharge lines fluidly connected to the first and second oil chambers respectively, a drain line, the pressure oil line, the first supply/discharge line, A switching valve set for switching the connection state of the second supply/discharge line and the drain line, the first valve shaft being liquid-tightly and rotatably housed in an installation hole formed in the housing; a second valve shaft accommodated in the shaft hole of the valve shaft so as to be rotatable around the axis, one of the first and second valve shafts acting as an input valve shaft and the other of the first and second valve shafts A switching valve set that acts as a feedback valve shaft, and a feedback arm that rotates the feedback valve shaft relative to the input valve shaft around an axis according to the movement of the connecting arm. Axial piston device. The installation hole is provided with an inflow port to which the pressure oil line is fluidly connected, and first and second connection ports to which the first and second supply/discharge lines are fluidly connected, respectively,
The drain line has a drain oil passage formed in the second valve shaft,
The first valve shaft has an inflow opening and a first connection opening at different positions in the circumferential direction for communicating the inflow port, the first connection port, and the second connection port with the axial holes of the first valve shaft, respectively. and a second connection opening,
The second valve shaft has a drain area in which an inlet end of the drain oil passage is opened at different positions in the circumferential direction, and the inflow port can be selectively fluidly connected to the first and second connection ports. having an oil passage region and first and second blocking regions capable of blocking the first and second connection ports, respectively;
When the input valve shaft is rotated in one of the first direction and the second direction about the axis with respect to the feedback valve shaft, the inflow port is connected to one of the first and second connection ports through the oil passage area. and the other of said first and second connection ports is fluidly connected to the inlet end of said drain line through said drain region, and said servo piston moves in the corresponding axial direction. On the other hand, when the feedback valve shaft is axially rotated relative to the input valve shaft via the feedback arm in response to axial movement of the servo piston, the first and second 2. The axial piston device according to claim 1, wherein a connection port is closed by said first and second closed areas, respectively, and a holding state is created in which said servo piston is held in position in the axial direction. The first valve shaft is positioned between the first and second connection openings in the circumferential direction, and is liquid-tightly slidable on the inner peripheral surface of the installation hole between the first and second connection ports. an intermediate arc region extending circumferentially from the intermediate arc region through the first connection opening to a side adjacent to the inflow opening, and extending between the first connection port and the inflow port on the inner peripheral surface of the installation hole; and a first arcuate area that can slide in a liquid-tight manner against the second connection port and the inflow port. 3. The axial piston device according to claim 2, further comprising a second arcuate region which is in liquid-tight sliding contact with the inner peripheral surface of the installation hole. the drain region is located circumferentially between the first and second closed regions;
4. The axial piston device according to claim 2, wherein the drain oil passage releases the drain oil that has flowed in from the inlet end into the internal space of the housing. The housing includes a first end wall portion that supports a first end portion of the rotating shaft closer to the swash plate main body of the movable swash plate than the axial piston member so as to be rotatable around the axis; A second end wall portion that supports a second end portion opposite to the first end portion so as to be rotatable about the axis, and a peripheral wall portion that connects peripheral edges of the first and second end wall portions. ,
The peripheral wall portion is provided with a bearing portion that supports the swash plate shaft of the movable swash plate and a radial opening that opens the bearing portion outward,
The housing further comprises a lid detachably attached to the peripheral wall so as to close the radial opening,
5. The axial piston device according to claim 1, wherein said switching valve set is supported by said cover. The servo space is formed at a corner of the housing where the vicinity of the radial opening of the peripheral wall and the first end wall are connected, and the longitudinal direction of the servo space is the axis of the rotation shaft and the rocking motion. 6. The axial piston device according to claim 5, wherein the axial piston device is provided perpendicular to both axes. the installation hole is formed in the lid so that the axis thereof is parallel to the swinging axis of the movable swash plate,
The feedback arm has a free end extending in a direction orthogonal to the axis of the switching valve set, with the base end connected to the feedback valve shaft so as not to rotate relative to the axis,
The connecting arm has a base end connected to the shaft portion of the movable swash plate so as not to rotate relative to the axis, and a free end engaged with the servo piston in a direction perpendicular to the swing axis of the movable swash plate. extends to
7. The axial system according to claim 5, wherein said feedback arm and said connecting arm are operatively connected via a recessed and protruding structure that can be engaged and disengaged according to attachment and detachment of said cover to and from said peripheral wall portion. piston device. The housing integrally has the first end wall portion and the peripheral wall portion, a case body having an opening on the opposite side of the peripheral wall portion to the first end wall portion, and a 8. The axial piston device according to claim 5, further comprising a port block detachably connected to the case body and forming the second end wall portion. a reference position biasing mechanism that biases the input valve shaft toward the reference position around the axis;
The reference position urging mechanism includes a reference position arm extending in a direction orthogonal to the input valve shaft with its base end connected to the input valve shaft so as not to rotate relative to the axis, and a reference position arm parallel to the swing axis. and an engaging pin erected on the reference position arm is accommodated in an accommodating space formed in the lid so that the longitudinal direction is perpendicular to the swing axis so that the engaging pin can freely move in the longitudinal direction. It has a reference position piston whose ends are engaged and a reference position biasing member that biases the reference position piston toward a longitudinal reference position corresponding to the reference position around the axis of the input valve shaft. An axial piston device according to any one of claims 5 to 8, characterized in that: wherein the first valve stem and the second valve stem act as the feedback valve stem and the input valve stem, respectively;
10. The axial piston device according to any one of claims 1 to 9, wherein the second valve shaft has an outer end forming an operation input portion that can be operated manually. wherein the first valve stem and the second valve stem act as the input valve stem and the feedback valve stem, respectively;
2. The first valve shaft is characterized in that the axial hole into which the second valve shaft is inserted is opened on the inner end surface and the outer end forms an operation input portion that can be operated manually. 10. An axial piston device according to any one of 10 to 9. An operation member that is manually operated, an operation sensor that detects the operation state of the operation member, a hydraulic operation mechanism that rotates the input valve shaft around an axis, and a control device that controls the operation of the hydraulic operation mechanism. ,
The hydraulic operation mechanism includes an operation arm that extends in a direction orthogonal to the input valve shaft with its base end connected to the input valve shaft so as not to rotate relative to the axis, and an operation arm that extends in a direction orthogonal to the input valve shaft, and The first and second operating oil chambers are accommodated in the accommodating space in a liquid-tight manner at one end and the other end in the longitudinal direction of the accommodating space formed in the housing. It is moved in the first longitudinal direction by pressure oil supply and pressure oil discharge from the second operation oil chamber, and is moved in the first longitudinal direction by pressure oil supply to the second operation oil chamber and pressure oil discharge from the first operation oil chamber. an operating piston that is longitudinally displaced, and the operating piston such that in response to first and second longitudinal movements of the operating piston, the input valve shaft is rotated about an axis in first and second directions, respectively; a connecting member for operatively connecting the piston and the operating arm; first and second operation biasing members respectively disposed in the first and second input oil chambers so as to clamp the operating piston; An operation pressure oil line for receiving pressure oil, an operation drain line, and first and second electromagnetic proportional valves for switching supply and discharge of pressure oil to and from the first and second operation oil chambers, respectively,
The first and second electromagnetic proportional valves are connected to the operation pressure oil line while blocking the corresponding operation oil chamber from the operation drain line. A holding state in which both the pressure oil line and the operation drain line are blocked, and a pressure oil discharge state in which the corresponding operation oil chamber is connected to the operation drain line while blocking the operation pressure oil line. configured to obtain
The control device controls the operation of the first and second electromagnetic proportional valves based on the signal from the operation sensor so that the input valve shaft is located at a position around the axis corresponding to the operation state of the operation member. 9. An axial piston device according to any one of claims 1 to 8, characterized in that: The first and second electromagnetic proportional valves each include a main body having a driving portion, an initial position for exhibiting the holding state, a projecting position for exhibiting the pressure oil supply state, and a storage position for exhibiting the pressure oil discharge state. a spool housed in the main body so as to move forward and backward in the axial direction so as to take a position;
The driving unit is in an ON state in which the spool is forcibly pushed in a protruding direction and positioned at the protruding position based on a control signal from the control device, and an ON state in which the spool is not substantially applied with a pushing force. configured to take an OFF state,
The spool has an oil chamber side pressure receiving portion that receives pressure from the operating oil chamber and generates a retracting direction pushing force that pushes the spool in the retracting direction. is substantially zero and in a state of equilibrium with the operating drain line, the initial position is taken, and in a state where the pushing force in the retracting direction exceeds the pressure of the operating drain line, the retracted position is taken in an oil chamber hydraulic pressure generation state. 13. Axial piston device according to claim 12. The drive unit has a pin that contacts the base end surface of the spool and pushes the spool in the projecting direction in the ON state,
In the OFF state, the drive unit allows the spool to take the initial position in the equilibrium state and the retracted position in the oil chamber hydraulic pressure generation state. 14. The axial piston device according to claim 13, wherein the pin is urged toward the proximal end surface of the spool so that the contact state of the proximal end surface of the spool is maintained.

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