JP4601276B2 - Axial piston type fluid pump / motor - Google Patents

Description

    The present invention relates to an axial piston type fluid pump motor having an improved timing plate.

As a conventional axial piston type fluid pump / motor, for example, the one described in Patent Document 1 below is known.
JP 2000-97146 A

  This is inserted into the casing, the cylinder block housed in the casing and rotatable around the axis, and slidably inserted into the cylinder chamber formed in the cylinder block, and protrudes when fluid flows into and out of the cylinder chamber. Alternatively, a plurality of plungers to be retracted, and a timing plate having a pair of arc-shaped fluid ports attached to the casing in a state of being interposed between the casing and the cylinder block and flowing in and out of the cylinder chamber And a notch groove extending toward the low-pressure side fluid port is formed at the rear end in the rotational direction of the high-pressure side fluid port at the sliding contact surface that is in sliding contact with the cylinder block of the timing plate.

  And what was described in this patent document 1 is a notch groove whose width and depth are gradually reduced as it approaches the low-pressure side fluid port, and the V notch having a V-shaped cross section or the depth is reduced. As the pressure port approaches the low-pressure side fluid port, the depth gradually becomes shallower, and a gradually shallow notch having a substantially rectangular cross section is used.

  Here, in recent years, in order to improve the performance of the axial piston type fluid pump / motor as described above (hereinafter referred to as fluid motor), the pressure of the fluid supplied to the fluid motor is increased to increase the speed of the fluid motor. However, when the fluid motor is rotated at a high speed as described above, there is a problem that a large noise is generated.

  The reason for this is that, as described above, when the fluid supply pressure is increased as described above, the speed of the fluid ejected through the notch into the cylinder chamber is also increased. As a result, this jet flows into the cylinder chamber (kidney port). This is because the impact noise when colliding with the inner surface is increased. Second, when fluid is ejected into the cylinder chamber (kidney port) as described above, fluid around the jet (fluid in the kidney port) As the jet velocity increases, the pressure drop increases and the cavitation occurs violently in a wider range.As a result, bubbles generated by cavitation are generated. This is considered to be because the impact sound when crushed increases.

  An object of the present invention is to provide an axial piston type fluid pump / motor that can effectively suppress noise during high-speed rotation while having a simple structure.

    The purpose of this is to insert a casing, a cylinder block housed in the casing and rotatable around an axis, and a cylinder chamber formed in the cylinder block so as to be slidable, when fluid flows into and out of the cylinder chamber. And a plurality of plungers that project or retract, and a timing that includes a pair of arc-shaped fluid ports that are attached to the casing in a state of being interposed between the casing and the cylinder block and that allow fluid to flow into and out of the cylinder chamber An axial piston type fluid pump having a notch groove extending toward the low pressure side fluid port at the rear end in the rotation direction of the high pressure side fluid port at the sliding contact surface that is in sliding contact with the cylinder block of the timing plate -In the motor, the notch groove has a cross-section of approximately four sections with the depth becoming shallower toward the low pressure side fluid port. This can be achieved by making the cross section of the notch groove into a substantially inverted trapezoidal shape by inclining both sides of the groove so as to expand toward the sliding contact surface. .

  In the present invention, the notch groove is constituted by a groove having a substantially square section whose depth becomes shallower toward the low-pressure side fluid port, and both side surfaces of the groove are inclined so as to expand toward the sliding contact surface. Therefore, since the cross section has a substantially inverted trapezoidal shape, the flow path cross-sectional area in the notch groove when the cylinder chamber is approaching the high pressure side fluid port is approaching the notch groove at any position. It becomes wider than the notch. As a result, the velocity of the fluid ejected through the notch groove to the cylinder chamber or the fluid port is reduced, thereby reducing the impact sound caused by the collision of the jet and reducing the pressure drop around the jet and reducing the cavitation. The impact sound when the bubbles are crushed is also reduced. In spite of such a simple structure, noise can be effectively suppressed even if the fluid pressure is increased in order to rotate at high speed.

Further, according to the second aspect of the present invention, it is possible to effectively suppress noise when the fluid motor performs the pumping action or when the fluid pump performs the motoring action by the same action as described above. Can do.
Furthermore, if it comprises as described in Claim 3, a noise can be suppressed strongly.
Moreover, if comprised as described in Claim 4, a noise can be suppressed more strongly .

Embodiment 1 of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 11 denotes an axial piston type fluid pump / motor, here, a swash plate type fluid motor. This fluid motor 11 has a case body 12, and a cross section extending toward the other end on one end surface of the case body 12. A circular storage chamber 13 is formed. In addition, a side plate 14 is fixed to one end of the case main body 12 by a bolt or the like (not shown), whereby the storage chamber 13 becomes a sealed space with its one end opening closed by the side plate 14. The case body 12 and the side plate 14 described above constitute a casing 15 of the fluid motor 11 as a whole.

  Reference numeral 16 denotes a rotating shaft having one side portion inserted into the storage chamber 13, and the rotating shaft 16 can be rotated to the casing 15 through a pair of bearings 17 and 18, more specifically, to the side plate 14 and the case main body 12, respectively. It is supported by. The other end of the rotating shaft 16 protrudes from the case body 12 and is connected to a speed reducer (not shown). Reference numeral 19 denotes a seal member interposed between the other end of the rotating shaft 16 and the case body 12.

  23 is a cylindrical cylinder block housed in the housing chamber 13 of the casing 15, a thrust member 24 having a substantially cylindrical shape is inserted into the cylinder block 23, and the thrust member 24, the cylinder block 23, Are connected to each other by spline connection. The thrust member 24 is fitted to the outside of the rotary shaft 16 and is connected to the rotary shaft 16 by spline coupling. As a result, the rotary shaft 16, the cylinder block 23, and the thrust member 24 rotate. The shaft 16 can rotate integrally around the axis.

  A plurality of cylinder chambers 25 extending in parallel to the axis are formed in the cylinder block 23, and these cylinder chambers 25 are arranged at equal distances in the circumferential direction. Plural (the same number as the cylinder chambers) plungers 26 are slidably inserted into the cylinder chambers 25, and a spherical sphere portion 27 is formed at the tip, that is, the other end of each plunger 26. Each cylinder chamber 25 has an arcuate kidney port 28 centered on the axis at one end, and these kidney ports 28 open to one end surface of the cylinder block 23.

  31 is a swash plate disposed in the casing 15 on the other side of the cylinder block 23, more specifically, in the storage chamber 13 between the other end surface of the cylinder block 23 and the other side inner surface of the casing 15. The shaft 15 is non-rotatably connected to the casing 15 by pins or the like not shown, and the rotating shaft 16 passes through the inside thereof. An inclined surface 32 of the swash plate 31 facing the cylinder block 23 is inclined with respect to a vertical plane perpendicular to the axis. As a result, the swash plate 31 has a thick portion 33 and a thin portion 34 with the center as a boundary. Can be divided into 35 is the same number of shoes as the plunger 26, and each shoe 35 is formed with a ball hole 36 in which almost half of the ball portion 27 is accommodated.

  The tip (other end) of each plunger 26 is slidably engaged with the inclined surface 32 of the swash plate 31 via the shoe 35. As a result, when a fluid is supplied (inflowed) to the cylinder chamber 25, the plunger 26 rotates from the thick portion 33 toward the thin portion 34 while gradually protruding from the cylinder chamber 25, while the fluid flows from the cylinder chamber 25. Is discharged (outflowed), the plunger 26 rotates from the thin portion 34 toward the thick portion 33 while gradually retracting into the cylinder chamber 25.

  Reference numeral 38 denotes a substantially ring-shaped retainer plate that is loosely fitted to the outside of the rotary shaft 16, and the retainer plate 38 is disposed between the cylinder block 23 and the swash plate 31. The retainer plate 38 is engaged with all the shoes 35, and the radially inner end thereof is in spherical contact with the outer periphery of the other end of the thrust member 24. 39 is a spring disposed between the snap ring 40 and the thrust member 24, which are locked to the inner periphery of one end of the cylinder block 23. The biasing force of the spring 39 is 35, the shoe 35 is pressed against the inclined surface 32 of the swash plate 31, and is transmitted to the cylinder block 23 to press the cylinder block 23 against a timing plate described later.

  In FIGS. 1, 2, 3, and 4, 42 is interposed between the cylinder block 23 and the casing 15, more specifically, in a state of being in surface contact with the side plate 14, and has a ring shape slightly larger in diameter than the cylinder block 23. The timing plate 42 is non-rotatably attached to the casing 15 via pins or the like. The timing plate 42 is formed with a pair of fluid ports 43, 44 having a long arc shape centering on the axis, and the fluid port 43 is on one side of a straight line connecting the protruding stroke end and the retracting stroke end of the plunger 26, The fluid ports 44 are disposed on the other side of the straight line and are separated from each other by 180 degrees in the circumferential direction.

  Reference numerals 45 and 46 denote inflow / outflow passages formed in the casing 15, specifically the side plate 14. The inflow / outflow passage 45 is always in communication with the fluid port 43, and the inflow / outflow passage 46 is in communication with the fluid port 44. These inflow and outflow passages 45 and 46 are connected to a pump and a tank via a switching valve (not shown), and when the switching valve is switched, one of them is on the high pressure (supply) side and the rest is on the low pressure (discharge) side. Become.

  Then, when the inflow / outflow passage 45 is connected to the pump and becomes the high pressure side, and the inflow / outflow passage 46 is connected to the tank and becomes the low pressure side, the high pressure side fluid port 43 is supplied from the inflow / outflow passage 45 The high pressure fluid is guided to the cylinder chamber 25 located on one side of the straight line, while the low pressure side fluid port 44 guides the low pressure fluid discharged from the cylinder chamber 25 located on the other side of the straight line to the inflow / outflow passage 46, and the cylinder block 23 is rotated forward in the direction indicated by the arrow in FIG.

  On the contrary, when the inflow / outflow passage 46 is connected to the pump to the high pressure side, and the inflow / outflow passage 45 is connected to the tank to the low pressure side, the high pressure side fluid port 44 is disconnected from the inflow / outflow passage 46. While the supplied high-pressure fluid is guided to the cylinder chamber 25, the low-pressure side fluid port 43 guides the low-pressure fluid discharged from the cylinder chamber 25 to the inflow / outflow passage 45, and the direction indicated by the arrow in FIG. Reverse rotation in the reverse direction.

  As described above, when high-pressure fluid is supplied to the inflow / outflow passage 45, the fluid port 43 becomes a high-pressure side fluid port and the cylinder block 23 rotates in the forward direction. An arc-shaped notch groove 51 extending toward the fluid port 44 that is a low-pressure side fluid port is formed in the sliding contact surface 50 that is in sliding contact with the cylinder block 23 of the plate 42. On the other hand, when a high-pressure fluid is supplied to the inflow / outflow passage 46, the fluid port 44 becomes a high-pressure side fluid port and the cylinder block 23 rotates in the reverse direction. An arc-shaped cutout groove 52 extending toward the fluid port 43 that is the low-pressure side fluid port is formed on the sliding contact surface 50 of the timing plate 42 at the end. Here, the aforementioned rotation direction means the rotation direction of the cylinder block 23.

  If notched grooves 51 and 52 are provided at such positions, the kidney port 28 of the cylinder chamber 25 overlaps with the high-pressure side fluid port 43 or 44 by the rotation of the cylinder block 23, and the high-pressure side fluid port. Just before a large amount of high-pressure fluid flows into the cylinder chamber 25 from 43 or 44, a small amount of high-pressure fluid flows into the cylinder chamber 25 through the notch groove 51 or 52 while gradually increasing the flow rate. The abrupt and large pressure change can be relieved and noise can be reduced.

  Here, the notch grooves 51 and 52 are both gradually reduced in depth toward the low pressure side fluid port (the fluid port 44 for the notch groove 51 and the fluid port 43 for the notch groove 52). The radial cross section is composed of grooves having a substantially rectangular shape, and both side surfaces 53 and 54 of these grooves are inclined so as to expand toward the sliding contact surface 50 (cylinder block 23). As a result, the radial cross section of the notch grooves 51 and 52 has a trapezoidal shape having a long side on the sliding contact surface 50 side and a short side on the bottom surface. The notched grooves 51 and 52 having such a shape can be easily cut by a milling machine or the like using a cutting tool (for example, an end mill) that matches the cross-sectional shape of the notched grooves 51 and 52. There is no increase in processing costs.

  When the notch grooves 51 and 52 are configured as described above, the cylinder chamber 25 (kidney port 28) approaches the notch groove 51 or 52 by the rotation of the cylinder block 23 and approaches the high pressure side fluid port 43 or 44. In other words, in other words, when the overlap amount between the kidney port 28 and the notch groove 51 or 52 is gradually increased, the flow path cross-sectional area of the high-pressure fluid flowing through the notch groove 51 or 52 is Any circumferential position is wider than the notch groove (V notch, gradually shallow notch) described in the background art.

  As a result, the speed of the fluid ejected to the cylinder chamber 25 (kidney port 28) through the notch groove 51 or 52 is reduced, thereby reducing the impact sound caused by the collision of the jet and the pressure around the jet. The drop is also reduced and the impact sound when the cavitation bubbles are crushed is also reduced. In spite of such a simple structure, noise can be effectively suppressed even if the fluid pressure is increased in order to rotate at high speed.

  Further, in the first embodiment, notch grooves 57 and 58 extending toward the high-pressure side fluid ports 43 and 44 are provided at the front end in the rotational direction of the low-pressure side fluid ports 44 and 43 on the sliding contact surface 50, respectively. The cut-out grooves 57, 58 are formed of grooves having a substantially rectangular cross section (inverted trapezoidal shape) whose depth becomes shallower toward the fluid ports 43, 44 on the low pressure side, and both side surfaces of the grooves. 53 and 54 are inclined so as to expand toward the sliding contact surface 50.

  If the notch grooves 57 and 58 are provided in the fluid ports 44 and 43 in this way, when the switching valve is switched from the flow position to the neutral position and the fluid motor 11 performs the pumping action, the cylinder chamber 25 The high-pressure fluid pushed out by the plunger 26 is ejected to the low-pressure side fluid port 44 through the notch groove 57 during forward rotation and to the low-pressure side fluid port 43 through the notch groove 58 during reverse rotation. Since the speed of the jet can be reduced as described above, noise can be effectively suppressed. In the above-described embodiment, the notch grooves 51, 52, 57, and 58 are provided because the fluid motor 11 rotates forward and backward. However, when the fluid motor 11 rotates only in one direction (for example, forward rotation), The notched grooves 52 and 58 may be omitted, or the V notch and the gradually shallow notch described in the background art may be used.

  Here, if the inclination angle (inclination angle with respect to a straight line perpendicular to the sliding contact surface 50) A of the notch grooves 51, 52, 57, 58 is 30 degrees or more, the noise is strongly increased. Can be suppressed. However, if the inclination angle A exceeds 50 degrees, the width at the base end of the notch grooves 51, 52, 57, 58 becomes wider than the width of the fluid ports 43, 44, and the noise suppressing effect is saturated. There is. For this reason, the inclination angle A is preferably in the range of 30 to 50 degrees.

Further, the radial cross-sectional areas of the notch grooves 51, 52, 57, and 58 at positions separated from the front ends of the notch grooves 51, 52, 57, and 58 by 10 degrees toward the fluid ports 43 and 44 in the circumferential direction. When 3 mm ² or more, noise can be suppressed more strongly. However, if the cross-sectional area exceeds 6 mm ² , the circumferential lengths of the cutout grooves 51, 52, 57, 58 may be shortened, and the noise suppression effect may be reduced. Therefore, the cross-sectional area is preferably in the range of 3 to 6 mm ² .

Next, the operation of the first embodiment will be described.
Now, it is assumed that the switching valve is switched so that the inflow / outflow passage 45 and the fluid port 43 are connected to the pump to the high pressure side, and the inflow / outflow passage 46 and the fluid port 44 are connected to the tank to the low pressure side. At this time, high-pressure fluid is supplied (inflow) from the inflow / outflow passage 45 to the cylinder chamber 25 located on one side of the straight line through the fluid port 43, and the plunger 26 in the cylinder chamber 25 protrudes toward the swash plate 31 so as to be inclined. Press to 32. As a result, a force directed toward the thinnest portion of the swash plate 31 acts on the plungers 26, thereby applying a torque around the axis to the cylinder block 23. As a result, the plunger 26, the cylinder block 23, and the rotating shaft 16 are integrally rotated in the forward rotation direction. At this time, the plunger 26 on one side together with the shoe 35 is placed on the inclined surface 32 on the thinnest portion of the swash plate 31. Slide towards.

  By such rotation of the cylinder block 23, the plunger 26 located on the other side of the straight line moves toward the thickest part of the swash plate 31 while engaging the inclined surface 32 of the swash plate 31 via the shoe 35. Therefore, it is pushed by the inclined surface 32 and gradually retracts into the cylinder chamber 25, the fluid in the cylinder chamber 25 is pushed out, and discharged (outflow) to the tank through the fluid port 44 and the inflow / outflow passage 46. Then, due to the rotation of the cylinder block 23 as described above, the connection between the cylinder chamber 25 and the fluid ports 43 and 44 located on one side and the other side of the straight line changes one after another.

  Here, when the kidney port 28 of the cylinder chamber 25 that has slightly moved from the retracting side stroke end to the thin-walled portion 34 side of the swash plate 31 reaches the notch groove 51 and overlaps, the high-pressure fluid is transferred to the cylinder through the notch groove 51. The notch groove 51 is composed of a substantially rectangular groove whose depth becomes shallower toward the low-pressure side fluid port 44, and the both sides of the groove are ejected into the chamber 25 (kidney port 28). Since 53 and 54 are inclined so as to expand toward the sliding contact surface 50, the speed of the fluid ejected into the cylinder chamber 25 (kidney port 28) is reduced, thereby effectively suppressing noise. The

  Further, when the switching valve is switched so that the inflow / outflow passage 46 is connected to the pump and the inflow / outflow passage 45 is connected to the tank, the high pressure fluid from the inflow / outflow passage 46 and the fluid port 44 is located on the other side of the straight line. The fluid pushed out from the cylinder chamber 25 located on one side of the straight line is discharged (outflowed) from the fluid port 43 and the inflow / outflow passage 45, and the rotating shaft 16 and the cylinder block 23 are reversed. Rotate to. If the kidney port 28 overlaps the notch groove 52 in such a state, the high-pressure fluid is ejected to the cylinder chamber 25 (kidney port 28) through the notch groove 52. The speed of the fluid ejected into the chamber 25 (kidney port 28) is reduced, and thus noise is effectively suppressed.

  When the switching valve is switched from the flow position to the neutral position and the fluid motor 11 performs the pumping action, the high-pressure fluid pushed out from the cylinder chamber 25 by the plunger 26 passes through the notch groove 57 during normal rotation. At the time of reverse rotation, the low pressure side fluid port 44 is ejected to the low pressure side fluid port 43 through the notch groove 58. At this time, the speed of the jet flow can be reduced in the same manner as described above. Can be suppressed.

    FIG. 5 shows a second embodiment of the present invention. In the second embodiment, an arc-shaped groove 60 having a rectangular cross section with the same width as the groove bottom is formed at the groove bottom of each notch groove 59. If the arc-shaped groove 60 is further formed in the groove bottom of the notch groove 59 in this way, the flow path cross-sectional area increases, and noise can be more effectively suppressed.

    FIG. 6 is a diagram showing Embodiment 3 of the present invention. In the third embodiment, the groove bottom of each notch groove 61 is formed in a cross-sectional arc shape so as to become deeper toward the center in the width direction. In this way, the flow of fluid becomes smooth, and the cross-sectional area of the flow path can be slightly increased as compared with a flat groove bottom, so that noise can be more effectively suppressed.

    Next, test examples will be described. In this test, a conventional motor in which V-notches are formed on both the front and rear ends of the high-pressure and low-pressure side fluid ports, and on both the front and rear ends of the high-pressure and low-pressure side fluid ports on the rear side. The width and depth are constant regardless of the circumferential position of the test motor having the notch groove described in the first embodiment and the front and rear ends of the high pressure and low pressure fluid ports. A reference motor having a known equi-depth notch having a substantially rectangular cross section was prepared.

  And noise was measured changing the rotation speed per unit time of each of these motors, and the result is shown in FIG. In the figure, the curve indicated by the alternate long and short dash line corresponds to the V-notched conventional motor, the curve indicated by the solid line corresponds to the test motor of the notched groove of the present application, and the curve indicated by the dotted line corresponds to the reference motor of the equal depth notch. It can be understood that the noise in the test motor is effectively suppressed when rotating at a higher speed than the noise in the conventional motor. In the reference motor, since a certain amount of fluid passes through the iso-depth notch and jets into the cylinder chamber from the beginning of the overlap of the kidney port and the iso-depth notch, the pressure change is insufficiently relaxed. Even at the number of rotations, a larger noise than the test motor is generated.

    In the above-described embodiment, the case where the fluid pump / motor is a swash plate type fluid motor has been described. However, in the present invention, a slant shaft type fluid motor may be used. In the above-described embodiments, the swash plate type fluid motor has been described. However, in the present invention, a swash plate type or a swash shaft type fluid pump may be used. In this case, when the plunger retracts into the cylinder chamber, the high pressure fluid is discharged (outflow) through the high pressure side fluid port, while when the plunger protrudes from the cylinder chamber, the low pressure fluid is sucked (inflow) through the low pressure side fluid port. .

  Furthermore, in the above-described embodiment, the inclination angle A of the both side surfaces 53, 54 of the notch grooves 51, 52, 57, 58 is the same at any circumferential position. The inclination angle of these both side surfaces may be changed at the portion, for example, the inclination angle on the base end side (side close to the fluid port) may be larger than the inclination angle on the distal end side. In this way, the channel cross-sectional area becomes larger and the noise reduction effect is improved.

  The present invention can be applied to an axial piston type, that is, a swash plate type and a slant axis type fluid pump motor.

It is front sectional drawing which shows Example 1 of this invention. It is a right view of a timing plate. FIG. 3 is a cross-sectional view taken along the arrow I-I in FIG. 2. It is II-II arrow sectional drawing of FIG. It is sectional drawing similar to FIG. 4 which shows Example 2 of this invention. It is sectional drawing similar to FIG. 4 which shows Example 3 of this invention. It is a graph which shows a test result.

11 ... Fluid pump / motor 15 ... Casing
23 ... Cylinder block 25 ... Cylinder chamber
26 ... Plunger 42 ... Timing plate
43, 44 ... Fluid port 50 ... Sliding contact surface
51, 52, 57, 58 ... Notch groove 53, 54 ... Side A ... Inclination angle

Claims (4)

    A casing, a cylinder block housed in the casing and rotatable about an axis, and a slidable insertion into a cylinder chamber formed in the cylinder block, and a plurality of protrusions or retractions when fluid flows into and out of the cylinder chamber A plunger, and a timing plate having a pair of arc-shaped fluid ports that are attached to the casing in a state of being interposed between the casing and the cylinder block and that allow the fluid to flow into and out of the cylinder chamber, In the axial piston type fluid pump / motor in which a notch groove extending toward the low-pressure side fluid port is formed at the rear end in the rotation direction of the high-pressure side fluid port on the sliding contact surface that is in sliding contact with the cylinder block of the timing plate. The notch groove is composed of a groove with a substantially square cross section that becomes shallower toward the low pressure side fluid port. Together, by inclining to widened toward both sides of the groove to the sliding surface, the axial piston pump-motor, characterized in that the cross-section of the cutout groove and a generally inverted trapezoidal shape.     In the sliding contact surface, a notch groove extending toward the high pressure side fluid port is also formed at the front end in the rotation direction of the low pressure side fluid port, and the depth of the notch groove becomes shallower toward the high pressure side fluid port. 2. The axial according to claim 1, wherein the groove is formed of a substantially rectangular groove, and the both sides of the groove are inclined so as to expand toward the slidable contact surface, whereby the cross-section of the notched groove is substantially inverted trapezoidal. Piston type fluid pump / motor.     The axial piston type fluid pump motor according to claim 1 or 2, wherein an inclination angle of both side surfaces of the groove is in a range of 30 to 50 degrees. Axial piston pump-motor according to claim 1 which is in the range of the cross-sectional area. 3 to 6 mm ² at a position apart by 10 degrees to the fluid port side from the tip of the notched groove.

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