Patent Description:
<CIT> discloses a fluid device at least not showing the features of the characterizing portion of claim <NUM>. Known hydraulic pump motors are disclosed in, for example, Patent Literature <NUM>. Patent Literature <NUM> discloses that oil channels for distributing hydraulic oil are provided on a spindle at different positions in the circumferential direction. Patent Literature <NUM> further discloses a restraining member <NUM> forming the oil channels for delivering the hydraulic oil. The restraining member <NUM> has grooves depressed from the outer peripheral surface of the restraining member <NUM> and through holes extending through the restraining member <NUM> in the axial direction and positioned inside the grooves in the radial direction. The grooves and through holes are selectively in communication with each other. The restraining member <NUM> is fitted with a cylindrical hole <NUM> using shrink-fitting, which radially externally surrounds the restraining member <NUM> around its entire circumference.

According to the conventional technique disclosed in Patent Literature <NUM>, however, the oil channels are formed between the outer peripheral surface of the restraining member <NUM> and the inner peripheral surface of the cylindrical hole <NUM>. This in turn means that a plurality of grooves are formed on the outer peripheral surface of the restraining member <NUM> and arranged next to each other in the axial direction. With such a structure, a small axial size of the restraining member <NUM> may hinder the fluid device from operating by hydraulic oil fed thereto and discharged therefrom. Therefore, the fluid device faces difficulties in achieving a smaller thickness.

The present invention provides a fluid device that, while being simply structured, can achieve a small size and save a space.

According to the fluid device relating to one aspect of the present invention, the first and second flow channels are linked through the distributor plate having grooves on their end surfaces to serve as connecting groove flow channels, so that the fluid can be distributed to the second flow channels that are larger in number than the first flow channels. In the direction from the first housing toward the second housing, it is only the thickness of the distributor plate that is required to distribute the fluid between the first flow channels and the second flow channels. When compared with the conventional art, the size of the device can be reduced in the direction extending from the first housing to the second housing.

The connecting groove flow channels may be formed on respective one of the end surfaces of the distributor plate.

The through flow channels may be spaced away from each other at equal intervals in the circumferential direction on the end surfaces.

The connecting groove flow channels may include: an outer circumferential connecting groove flow channel located radially outside the through flow channels, where the outer circumferential connecting groove flow channel connects the through flow channels; and an inner circumferential connecting groove flow channel located radially inside the through flow channels, where the inner circumferential connecting groove flow channel connects together the through flow channels.

The third flow channel may further include: outward radial groove flow channels formed on the end surfaces and extending in a radial direction, where the outward radial groove flow channels radially connects the through flow channels and the outer circumferential connecting groove flow channel; and inward radial groove flow channels formed on the end surfaces and extending in the radial direction, where the inward radial groove flow channels radially connects the through flow channels and the inner circumferential connecting groove flow channel. The outward and inward radial groove flow channels may be connected to adjacent ones or every other ones of the through flow channels that are arranged next to each other in the circumferential direction.

The outward and inward radial groove flow channels may be arranged such that adjacent two or four of the through flow channels arranged next to each other in the circumferential direction form one group and the groups of the through flow channels are arranged next to each other in the circumferential direction.

& The inner circumferential connecting groove flow channel, the through flow channels and the outer circumferential connecting groove flow channel may be arranged on concentric circles respectively on the end surfaces.

The second housing may include: an oscillating housing part extending along an axis; internal teeth formed on an inner peripheral surface of the oscillating housing part; a carrier supported on the oscillating housing part such that the carrier is rotatable around the axis, where the carrier is held with two bearings spaced away from each other in a direction extending along the axis of the oscillating housing part; a crankshaft supported on the carrier such that the crankshaft is rotatable around another axis parallel to the axis; an oscillating gear meshing with the internal teeth, where rotation of the oscillating gear is restricted by the crankshaft to oscillatory rotation; and a feeding and discharging plate having a plurality of feeding and discharging channels for feeding a working fluid to a space between the inner peripheral surface of the oscillating housing part and the oscillating gear and for discharging a working fluid from a space between the inner peripheral surface of the oscillating housing part and the oscillating gear. The feeding and discharging plate may be located on the oscillating gear to face the first housing in a direction extending along the axis, and the feeding and discharging channels may be in communication with the second flow channels.

The inner and outer circumferential connecting groove flow channels may be configured to feed and discharge a working fluid under different pressures or under a same pressure.

A fluid device according to another aspect of the present invention has a first housing having one or more first flow channels; a second housing having second flow channels that are larger in number than the first flow channels; and a distributor plate having a third flow channel connecting a predetermined one of the first flow channels and predetermined ones of the second flow channels. The distributor plate is sandwiched between the first housing and the second housing in a thickness direction of the distributor plate such that end surfaces of the distributor plate are in contact respectively with the first and second housings. The second housing includes: an oscillating housing part extending along an axis; internal teeth formed on an inner peripheral surface of the oscillating housing part; a carrier supported on the oscillating housing part such that the carrier is rotatable around the axis, where the carrier is held with two bearings spaced away from each other in a direction extending along the axis of the oscillating housing part; a crankshaft supported on the carrier such that the crankshaft is rotatable around another axis parallel to the axis; an oscillating gear meshing with the internal teeth, where rotation of the oscillating gear is restricted by the crankshaft to oscillatory rotation; and a feeding and discharging plate having a plurality of feeding and discharging channels for feeding a working fluid to a space between the inner peripheral surface of the oscillating housing part and the oscillating gear and for discharging a working fluid from a space between the inner peripheral surface of the oscillating housing part and the oscillating gear. The feeding and discharging plate is located on the oscillating gear to face the first housing in a direction extending along the axis, and the feeding and discharging channels are in communication with the second flow channels. The third flow channel includes: a plurality of through flow channels arranged next to each other in a circumferential direction, where the through flow channels open at the end surfaces; an outer circumferential connecting groove flow channel extending along the circumferential direction and formed on each of the end surfaces as a connecting groove flow channel connecting together the through flow channels, where the outer circumferential connecting groove flow channel is located outside the through flow channels in a radial direction and the outer circumferential connecting groove flow channel connecting the through flow channels; an inner circumferential connecting groove flow channel extending along the circumferential direction and formed on each of the end surfaces as the connecting groove flow channel, where the inner circumferential connecting groove flow channel is located inside the through flow channels in the radial direction and the inner circumferential connecting groove flow channel connects the through flow channels; outward radial groove flow channels formed on the end surfaces and extending in the radial direction, where the outward radial groove flow channels radially connects the through flow channels and the outer circumferential connecting groove flow channel; and inward radial groove flow channels formed on the end surfaces and extending in the radial direction, where the inward radial groove flow channels radially connects the through flow channels and the inner circumferential connecting groove flow channel. The outward and inward radial groove flow channels are connected to adjacent ones or every other ones of the through flow channels that are arranged next to each other in the circumferential direction, adjacent four of the through flow channels that are arranged next to each other in the circumferential direction form one group, and the outward and inward radial groove flow channels are arranged such that the groups of the through flow channels are arranged next to each other in the circumferential direction.

With the configurations described above, the first and second flow channels are linked through the distributor plate having grooves on their end surfaces to serve as connecting groove flow channels, so that the fluid can branch and/or merge between the first flow channels and the second flow channels that are larger in number than the first flow channels. In the direction from the first housing toward the second housing, it is only the thickness of the distributor plate that is required to cause the fluid to be distributed between the first flow channels and the second flow channels. When compared with the conventional art, the size of the device can be reduced in the direction from the first housing to the second housing.

Unlike the disclosure in Patent Literature <NUM>, there is no need of forming multiple grooves depressed from the outer peripheral surface of the restraining member and arranged next to each other in the axial direction. Therefore, the fluid device can achieve a small axial size while being capable of operating by hydraulic oil fed thereto and discharged therefrom. In other words, the fluid device can accomplish a smaller thickness.

The above-described configurations can provide improved sealing since the present invention can avoid the risk of leakage of the hydraulic oil caused by an accidental gap between the cylindrical hole and the restraining member providing the flow channels (oil channels), which is likely to be disadvantages of the configuration disclosed in Patent Literature <NUM>. In addition, since the flat distributor plate is secured by being sandwiched between the first housing and the second housing, the distributor plate can remain pressed by a fastener or other members. This can provide for reliable tight sealing, thereby certainly improving the sealing.

In addition, the distributor plate can be manufactured simply by forming grooves on the end surfaces as the third flow channel. This means that cutting or casting can be used to make the distributor plate, thereby reducing the number of steps involved in and the time required for the manufacturing. Furthermore, since the necessary tight seal can be maintained simply by flattening the end surfaces of the distributor plate, there is no demand for excessively high machining accuracy. In this way, the necessary tight sealing can be accomplished while simplified manufacturing can be also achieved.

The present invention can provide a fluid device that, while being simply configured, is capable of achieving a small size and saving a space, keeping tight sealing of the hydraulic oil, and preventing leakage of the hydraulic oil, thereby improving the operating efficiency.

A first embodiment of a fluid device according to the invention will be hereinafter described with reference to the accompanying drawings. <FIG> is a side view (partial sectional view) of a hydraulic motor, which is an example of a fluid device according to an embodiment of the invention. <FIG> is a sectional view along a line II-II in <FIG>. <FIG> is an enlarged view of a portion III of <FIG>. <FIG> is an enlarged view of a portion IV of <FIG>. <FIG> is a sectional view along a line V-V in <FIG>. <FIG> is a sectional view along a line VI-VI in <FIG>. <FIG> is a sectional view along the line VII-VII in <FIG>. <FIG> is a sectional view showing the distributor plate. <FIG> is a sectional view along a line IX-IX in <FIG>. <FIG> is a sectional view along a line X-X in <FIG>. <FIG> is a sectional view showing the flow channels in the hydraulic motor. In the drawings, the reference numeral <NUM> indicates the hydraulic motor.

The following describes a fluid device relating to an embodiment of the present invention, taking a hydraulic motor as an example. The present embodiment, however, is not limited to such, and the fluid device can be a hydraulic pump mechanism, for example.

As shown in <FIG>, the hydraulic motor <NUM> includes a cylindrical oscillating housing part <NUM> and a rotatable part <NUM> that is rotatably supported on the inner peripheral surface of the oscillating housing part <NUM> via two bearings <NUM> and <NUM> (a first bearing <NUM> and a second bearing <NUM>). The bearings <NUM> and <NUM> are angular ball bearings. The present embodiment, however, is not limited to such, and the bearings <NUM> and <NUM> can be alternatively selected from a variety of bearings including other ball bearings such as deep groove ball bearings, or plain bearings, for example.

The central axis of the oscillating housing part <NUM> coincides with the axis of rotation of the rotatable part <NUM>. In the following description, the central axis and the axis of rotation are collectively referred to as a first axis C1 (an example of an axis). In the following description, the term "axial direction" may refer to a direction parallel to the first axis C1, the term "circumferential direction" may refer to the direction of the rotation of the rotatable part <NUM>, and the term "radial direction" may refer to the radial direction of the rotatable part <NUM>.

As shown in <FIG>, the oscillating housing part <NUM> is axially divided into a first oscillating housing <NUM> and a second oscillating housing <NUM>. The first oscillating housing <NUM> faces a first direction (located on the left side in <FIG>) in the axial direction. The second oscillating housing <NUM> faces a second direction opposite to the first direction (located on the right side in <FIG>) in the axial direction. The oscillating housing part <NUM> is not necessarily axially divided, but may not be axially divided. The first oscillating housing <NUM> is shaped like a cylinder. An outer flange <NUM> projecting outward in the radial direction is formed on an outer peripheral surface 7a of the first oscillating housing <NUM> near a first end 7b that faces the first direction. The outer flange <NUM> is used to attach the hydraulic motor <NUM> to external equipment, which is not shown. A through hole 9a penetrates the outer flange <NUM> in the thickness direction (axial direction). A bolt (not shown) extends through the through hole 9a.

A peripheral wall 7e of the first oscillating housing <NUM> has a thick portion <NUM> that is thicker than the other portion. The thick portion <NUM> extends from a second end 7d facing the second direction to the axial center of the first oscillating housing <NUM>. A second end 10c of the thick portion <NUM>, which faces the second direction, is on the same plane as the second end 7d of the first oscillating housing <NUM>. Stated differently, the second end 10c of the thick portion <NUM> forms a part of the second end 7d of the first oscillating housing <NUM>.

An inner peripheral surface 10d of the thick portion <NUM> has a plurality of (for example, thirteen in this embodiment) pin grooves 10a. The pin grooves 10a extend in the axial direction along the entire thick portion <NUM>, and are equally spaced away from each other in the circumferential direction. The pin grooves 10a have a semicircular shape when seen in the axial direction. Each pin groove 10a receives an internal tooth pin <NUM> (an example of an internal tooth) therein. The internal tooth pins <NUM> have a substantially cylindrical shape and are received in a rotatable manner. Since the pin grooves 10a have a semicircular shape when viewed in the axial direction, the internal tooth pins <NUM> radially inwardly protrude beyond the inner peripheral surface 10d of the thick portion <NUM> and the protruding portions of the internal tooth pins <NUM> are also shaped like a semicircle. The internal tooth pins <NUM> serve as internal teeth meshing with an oscillating gear <NUM>, which will be described below.

First through-holes <NUM> are formed in and extend through the outer peripheral portion of the thick portion <NUM> in the axial direction. The first through holes <NUM> are arranged between the pin grooves 10a and evenly spaced away from each other in the circumferential direction. There are, for example, eight first through holes <NUM>. The first through holes <NUM> receive shafts 20a of bolts <NUM> (introduced as an example of fastener parts and screws). Via the bolts <NUM>, the first oscillating housing <NUM>, the second oscillating housing <NUM>, and a feeding and discharging plate <NUM>, described below, are collectively tightened to form a single unit.

On the inner peripheral surface 7c of the first oscillating housing <NUM>, a first bearing receiving part <NUM> is formed via a step part 11a so as to have a large inner diameter. The first bearing receiving part <NUM> is located on the first direction side with respect to the thick portion <NUM>. An outer race 12a of the first bearing <NUM> is fitted into the first bearing receiving part <NUM>. The first bearing <NUM> and the first oscillating housing <NUM> are accurately positioned relative to each other by allowing the outer race 12a to abut against the step part 11a.

On the inner peripheral surface 7c of the first oscillating housing <NUM>, a seal receiving part <NUM> is formed via a step part 14a so as to have a large inner diameter. The seal receiving part <NUM> is located on the first direction side with respect to the first bearing receiving part <NUM>. A sealing part <NUM> is partially fitted in the seal receiving part <NUM>. The sealing part <NUM> provides sealing between the first oscillating housing <NUM> and the rotatable part <NUM>. For example, the sealing part <NUM> is a floating seal. The sealing part <NUM>, however, is not limited to such, and various seals such as packing or mechanical seals can be alternatively used.

On the first end 7b of the first oscillating housing <NUM>, a first-carrier first labyrinth part <NUM> is formed and has a greater inner diameter than the seal receiving part <NUM>. The first-carrier first labyrinth part <NUM> forms a first labyrinth <NUM>, when combined with the rotatable part <NUM>. The first labyrinth <NUM> prevents dust and other particles from entering from the outside into the space between the first oscillating housing <NUM> and the rotatable part <NUM>.

The second end 7d of the first oscillating housing <NUM> defines a plane by which the first and second oscillating housings <NUM> and <NUM> are separated. The second end 7d of the first oscillating housing <NUM> has an entirely flat outer peripheral portion. An O-ring groove <NUM>, which is annular when viewed in the axial direction, is formed on the second end 7d between the first through holes <NUM> and the outer peripheral portion. An O-ring <NUM> is placed in the O-ring groove <NUM>. The O-ring <NUM> provides for reliable sealing between the first and second oscillating housings <NUM> and <NUM>.

The second oscillating housing <NUM> is shaped like an annulus. A circumferential wall 8a of the second oscillating housing <NUM> has second through holes <NUM> formed therein. The second through holes <NUM> are positioned correspondingly to the first through holes <NUM> of the first oscillating housing <NUM> and in communication with the first through holes <NUM>. The second through holes <NUM> have the same diameter as and coaxial with the first through holes <NUM>. A large part of each second through hole <NUM> that faces the second direction forms a counterboring part <NUM>. The counterboring part <NUM> receives a head 20b of a corresponding one of the bolts <NUM>.

A first end 8b of the second oscillating housing <NUM> that faces the first direction defines a plane by which the first and second oscillating housings <NUM> and <NUM> are separated. A press plate <NUM> is integrally formed on the first end 8b of the second oscillating housing <NUM> and extends radially inwardly from the inner peripheral surface 8c of the second oscillating housing <NUM>. The press plate <NUM> has an annular shape when viewed in the axial direction. The press plate <NUM> closes, on the second direction side, working chambers 66a, 66b and 66c (see <FIG>) formed between the inner peripheral surface 7c of the first oscillating housing <NUM> and the outer peripheral surface of the oscillating gear <NUM>, which will be described below. When the first and second oscillating housings <NUM> and <NUM> are formed as a single unit, the press plate <NUM> can be, for example, formed as being separated from the oscillating housing part <NUM>.

In a large part of the inner peripheral surface 21a of the press plate <NUM>, excluding its end facing the first direction, a second-carrier first labyrinth part <NUM> is formed. The second-carrier first labyrinth part <NUM> has, via a step part 25a, a greater inner diameter than the inner peripheral surface 21a of the press plate <NUM>. The second-carrier first labyrinth part <NUM> forms a second labyrinth <NUM>, when combined with the rotatable part <NUM>. The second labyrinth <NUM> prevents the hydraulic oil from leaking out of the space between the second oscillating housing <NUM> and the rotatable part <NUM> (this will be described in detail below).

On the inner peripheral surface 8c of the second oscillating housing <NUM>, a second bearing receiving part <NUM> is formed via a step part 24a so as to have a large inner diameter. The second bearing receiving part <NUM> is located on the second direction side with respect to the press plate <NUM>. An outer race 13a of the second bearing <NUM> is fitted into the second bearing receiving part <NUM>. The second bearing <NUM> and the second oscillating housing <NUM> are accurately positioned relative to each other by allowing the outer race 13a to abut against the step part 24a.

An O-ring groove <NUM>, which is annular when viewed in the axial direction, is formed on the second end 8d of the second oscillating housing <NUM> that faces the second direction. An O-ring <NUM> is placed in the O-ring groove <NUM>. The O-ring <NUM> provides for reliable sealing between the second oscillating housing <NUM> and a cover <NUM> described below. The second end 8d of the second oscillating housing <NUM> has a plurality of internally threaded parts <NUM>. The internally threaded portions <NUM> are radially inside the O-ring groove <NUM> and evenly spaced away from each other in the circumferential direction. The internally threaded parts <NUM> are provided to secure the cover <NUM> onto the second oscillating housing <NUM>.

The cover <NUM> closes an opening 8e of the second oscillating housing <NUM> on the second-direction side. The cover <NUM> is made by, for example, subjecting a metal plate to stamping and has a central part a large part of which is swollen toward the second direction. The outer peripheral portion of the cover <NUM> forms an outer flange part 29a. The outer flange part 29a overlaps the second end 8d of the second oscillating housing <NUM>.

The outer flange part 29a has through holes 29b penetrating therethrough in the thickness direction of the cover <NUM>. The through holes 29b are positioned correspondingly to the internally threaded portions <NUM> of the second oscillating housing <NUM>. Bolts <NUM> are inserted into the through holes 29b from the second direction side. By tightening the bolts <NUM> into the internally threaded portions <NUM> of the second oscillating housing <NUM>, the cover <NUM> is secured to the second oscillating housing <NUM>.

The feeding and discharging plate (port plate) <NUM> is securely held by the bolts <NUM> inserted into the first through holes <NUM> of the first oscillating housing <NUM> and the second through holes <NUM> of the second oscillating housing <NUM>. The feeding and discharging plate <NUM> is located at a first end 10b of the thick portion <NUM>, which is one of the ends of the thick portion <NUM>. The feeding and discharging plate <NUM> is configured to feed hydraulic oil into and discharge hydraulic oil out of the working chambers 66a, 66b and 66c, which will be described below.

The feeding and discharging plate <NUM> has an annular shape when viewed in the axial direction. The outer diameter of the feeding and discharging plate <NUM> is the same as or slightly less than the diameter of the inner peripheral surface 7c of the first oscillating housing <NUM>. Therefore, the feeding and discharging plate <NUM> is fitted to the inner peripheral surface 7c of the first oscillating housing <NUM> and positioned at the first end 10b of the thick portion <NUM>.

The outer peripheral portion of the feeding and discharging plate <NUM> has internally threaded portions <NUM> that are positioned correspondingly to the first through holes <NUM> of the first oscillating housing <NUM>. The bolts <NUM> are inserted, from the second oscillating housing <NUM> side, into the second through holes <NUM> and then into the first through holes <NUM> and finally tightened into the internally threaded portions <NUM> of the feeding and discharging plate <NUM>. In this manner, via the bolts <NUM>, the first oscillating housing <NUM>, the second oscillating housing <NUM>, and the feeding and discharging plate <NUM> are collectively tightened to form a single unit.

In a portion of the feeding and discharging plate <NUM> that is radially inside of the internally threaded portions <NUM>, a plurality of through holes 46a (feeding and discharging ports) penetrating the feeding and discharging plate <NUM> in the thickness direction are formed. The through holes 46a can contribute to feed hydraulic oil into and discharge hydraulic oil out of the working chambers 66a, 66b and 66c, which will be described in detail below. The number of through holes 46a (feeding and discharging ports) corresponds to the number of pin grooves 10a formed in the first oscillating housing <NUM>. There are, for example, thirteen through holes 46a in the present embodiment. The through holes 46a (feeding and discharging ports) have openings facing the thick portion <NUM>, which are arranged in the middle between adjacent ones of the pin grooves 10a arranged next to each other in the circumferential direction and positioned radially inside the inner peripheral surface 10d of the thick portion <NUM>.

In a large part of the inner peripheral surface 46b of the feeding and discharging plate <NUM>, excluding its end facing the second direction, a plate labyrinth part <NUM> is formed. The plate labyrinth part <NUM> has, via a step part 48a, a greater inner diameter than the inner peripheral surface 46b of the feeding and discharging plate <NUM>. The plate labyrinth part <NUM> forms a third labyrinth <NUM>, when combined with the rotatable part <NUM>. The third labyrinth <NUM> prevents the hydraulic oil from leaking out of the space between the feeding and discharging plate <NUM> and the rotatable part <NUM> (this will be described in detail below).

The rotatable part <NUM>, which is rotatably held in the oscillating housing part <NUM>, is mainly constituted by a carrier (rotatable member) <NUM>, a plurality of (for example, in the present embodiment three) crankshafts <NUM>, and an oscillating gear <NUM>. The carrier <NUM> is rotatably supported via the bearings <NUM> and <NUM> on the respective sides in the axial direction, the crankshafts <NUM> are rotatably supported in the carrier <NUM>, and the oscillating gear <NUM> is rotatably supported by the crankshafts <NUM>. The carrier <NUM> is axially divided into a first carrier <NUM> and a second carrier <NUM>. The first carrier <NUM> faces the first direction. The second carrier <NUM> faces the second direction.

The first carrier <NUM> includes a disk-shaped substrate <NUM> and a plurality of (e.g., three in the present embodiment) pillars <NUM> protruding toward the second direction from a second end 33b of the substrate <NUM> that faces the second direction. In the first carrier <NUM>, the substrate <NUM> and pillars <NUM> are integrally molded. The outer peripheral surface 33c of the substrate <NUM> has a gradually increasing outer diameter, which is achieved by step parts, from the second end 33b toward the first end 33a that faces the first direction.

More specifically, the outer peripheral surface 33c of the substrate <NUM> is divided into a first outer peripheral surface 33d, a second outer peripheral surface 33e, a third outer peripheral surface 33f and a fourth outer peripheral surface <NUM>, which are arranged next to each other in the stated order starting from the second end 33b side. The second outer peripheral surface 33e is continuous from the first outer peripheral surface 33d via a large step part <NUM> and has a larger outer diameter than the first outer peripheral surface 33d. The third outer peripheral surface 33f is continuous from the second outer peripheral surface 33e via a small step part 33i and has a larger outer diameter than the second outer peripheral surface 33e. The fourth outer peripheral surface <NUM> is continuous from the third outer peripheral surface 33f via a medium step part 33j and has a larger outer diameter than the third outer peripheral surface 33f.

The portion of the first carrier <NUM> where the first outer peripheral surface 33d is formed is accommodated in the plate labyrinth part <NUM> of the feeding and discharging plate <NUM>. The outer diameter of the first outer peripheral surface 33d is slightly smaller than the inner diameter of the plate labyrinth part <NUM>. The second end 33b of the first carrier <NUM> is located on the second direction side with respect to the step part 48a of the feeding and discharging plate <NUM>. The first outer peripheral surface 33d and second end 33b of the first carrier <NUM> forms the third labyrinth <NUM> in conjunction with the plate labyrinth part <NUM> of the feeding and discharging plate <NUM>.

An inner race 12b of the first bearing <NUM> is fitted into the third outer peripheral surface 33f. The first bearing <NUM> and the first carrier <NUM> are accurately positioned relative to each other by allowing the inner race 12b to abut against the medium step part 33j. In this way, the first carrier <NUM> can be accurately positioned relative to the first oscillating housing <NUM>. Furthermore, the first carrier <NUM> is rotatably supported by the first oscillating housing <NUM> via the first bearing <NUM>.

The fourth outer peripheral surface <NUM> of the first carrier <NUM> faces the sealing housing part <NUM> of the first oscillating housing <NUM> in the radial direction. This results in the sealing part <NUM> being positioned between the fourth outer peripheral surface <NUM> of the first carrier <NUM> and the sealing housing part <NUM> of the first oscillating housing <NUM>.

A disk <NUM>, which is circular when viewed in the axial direction, is integrally formed on the end of the fourth outer peripheral surface <NUM> that faces the first direction. A second end 35b of the disk <NUM>, which faces the second direction, faces the first end 7b of the first oscillating housing <NUM> in the axial direction. The outer diameter of the disk <NUM> is the same as the diameter of the outer peripheral surface 7a of the first oscillating housing <NUM>. A sealing housing depression <NUM>, which is annular when viewed in the axial direction, is formed on the second end 35b of the disk <NUM>. The sealing housing depression <NUM> is smoothly continuous from the fourth outer peripheral surface <NUM>. The sealing part <NUM> is partially housed within the sealing housing depression <NUM>. In this way, sealing is established between the first carrier <NUM> (the rotatable part <NUM>) and the first oscillating housing <NUM>.

On the outer peripheral edge of the second end 35b of the disk <NUM>, a first-carrier second labyrinth part <NUM> is formed and has a smaller outer diameter via a step. The first-carrier second labyrinth part <NUM> forms the first labyrinth <NUM> in conjunction with the first-carrier first labyrinth part <NUM> formed in the first oscillating housing <NUM>. Since the first labyrinth <NUM> is positioned radially outside the sealing part <NUM>, dust and other particles can be reliably prevented from entering from the outside into the space between the first oscillating housing <NUM> and the first carrier <NUM> (the rotatable part <NUM>).

An outer flange <NUM> projecting outward in the radial direction is formed on the outer peripheral surface 35c of the disk <NUM>. The outer flange <NUM> is used to attach the hydraulic motor <NUM> to external equipment, which is not shown. A through hole 39a penetrates the outer flange <NUM> in the thickness direction (axial direction). A bolt (not shown) extends through the through hole 39a.

A plurality of (for example, three in this embodiment) shaft supporting depressions <NUM> are formed in the second end 33b of the substrate <NUM> and arranged at equal intervals in the circumferential direction. The shaft supporting depressions <NUM> are formed near the outer peripheral portion of the second end 33b (radially inside the first outer peripheral surface 33d). The shaft supporting depressions <NUM> rotatably support the crankshafts <NUM>. In the shaft supporting depressions <NUM>, first bearings 59a are fitted to rotatably support the crankshafts <NUM>. The first bearings 59a are, for example, plain bearings. The first bearings 59a, however, are not limited to such, and various bearings such as ball bearings can be alternatively used.

In the portion of the substrate <NUM> that is located radially inside the second outer peripheral surface 33e, a plurality of feeding channels <NUM>, a plurality of discharging channels <NUM>, and a drain passage (tank channel) <NUM> are formed and extend over the entire axial length of the substrate <NUM>. The feeding channels <NUM> are oil channels (flow channels) through which hydraulic oil is fed from a hydraulic pump (not shown). The feeding channels <NUM> open through the large step part <NUM> at their ends facing the second direction. In other words, each feeding channel <NUM> has a feeding opening 41a in the large step part <NUM>. The discharging channels <NUM> are oil channels (flow channels) through which hydraulic oil is discharged from inside the hydraulic motor <NUM>. The discharging channels <NUM> also open through the large step part <NUM> at the ends facing the second direction. In other words, each discharging channel <NUM> has a discharging opening 42a in the large step part <NUM>.

The numbers of feeding and discharging channels <NUM> and <NUM> are respectively different from the number of through holes 46a formed in the feeding and discharging plate <NUM> fixedly attached to the first oscillating housing <NUM>. For example, in the present embodiment, the numbers of feeding and discharging channels <NUM> and <NUM> are twelve, which is less by one than the number of through holes 46a in the feeding and discharging plate <NUM>. The feeding openings 41a of the feeding channels <NUM> and the discharging openings 42a of the discharging channels <NUM> are alternately arranged in the circumferential direction on the same pitch circle. Each of the feeding openings 41a and a corresponding one of the discharging openings 42a form a pair, and the pairs of the feeding and discharging openings 41a and 42a are arranged at regular intervals in the circumferential direction.

The drain passage <NUM> is a flow channel for returning leaking hydraulic oil in the hydraulic motor <NUM> back to a tank (not shown). The ends of the feeding channels <NUM>, discharging channels <NUM> and drain passage <NUM> (the ends facing the first direction) are in communication with an oil distributor <NUM> via a distributor plate <NUM>. The distributor plate <NUM> is provided at the first end 33a of the substrate <NUM>. The distributor plate <NUM> has flow channels <NUM> to <NUM> for distributing the hydraulic oil into a plurality of flow channels. The oil distributor <NUM> has a plurality of flow channels <NUM> to <NUM>, which will be described below. The distributor plate <NUM> is in contact with the first end 35a of the disk <NUM>, which faces the first direction.

Through the flow channels <NUM> to <NUM>, the hydraulic oil from the hydraulic pump is fed to the flow channels <NUM> to <NUM>. Then, through the distributing flow channels <NUM> to <NUM>, the hydraulic oil from the flow channels <NUM> to <NUM> can be fed to the feeding channels <NUM>. The hydraulic oil discharged into the discharging channels <NUM> is returned to a tank via the distributing flow channels <NUM> to <NUM> and the flow channels <NUM> to <NUM>, or returned again back to the feeding channels <NUM>. The hydraulic oil discharged into the drain passage <NUM> may also be returned to the tank via distributing flow channels (not shown). Note that how the hydraulic oil works will be described below in detail.

A gap is created between the large step part <NUM> of the first carrier <NUM> and the feeding and discharging plate <NUM>. In this gap, a sliding plate (piston plate) <NUM> is disposed. The sliding plate <NUM> has an annular shape when viewed in the axial direction. The inner peripheral surface of the sliding plate <NUM> is fitted to the first outer peripheral surface 33d of the first carrier <NUM>. The sliding plate <NUM> is non-rotatable relative to the first carrier <NUM> and slidable in the direction along the axis C1. The thickness of the sliding plate <NUM> is less than the gap between the large step part <NUM> and the feeding and discharging plate <NUM>.

The sliding plate <NUM> has a plurality of through holes (through ports) 50c correspondingly to the feeding openings 41a of the feeding channels <NUM> and the discharging openings 42a of the discharging channels <NUM>. The through holes 50c corresponding to the feeding openings 41a are coaxially located with the feeding openings 41a. The through holes 50c corresponding to the discharging openings 42a are coaxially located with the discharging openings 42a.

Each of the feeding and discharging openings 41a and 42a is provided with a cylindrical piston <NUM>. The pistons <NUM> are slidable in the feeding and discharging channels <NUM> and <NUM>. The pistons <NUM> are energized toward the sliding plate <NUM> by springs <NUM> provided in the feeding and discharging channels <NUM> and <NUM>. Thus, the pistons <NUM> are pressed against the sliding plate <NUM>.

The thickness of the sliding plate <NUM> is less than the gap between the large step part <NUM> and the feeding and discharging plate <NUM>. Therefore, due to the action of the springs <NUM>, the pistons <NUM> protrude beyond the large step part <NUM> to abut against the sliding plate <NUM>. The surface 50b of the sliding plate <NUM> that faces the second direction is therefore pressed against the feeding and discharging plate <NUM>. In this manner, via the pistons <NUM>, the feeding channels <NUM> are in communication with the through holes 50c in the sliding plate <NUM>. Furthermore, via the pistons <NUM>, the discharging channels <NUM> are in communication with the through holes 50c of the sliding plate <NUM>. In addition, the through holes 50c in the sliding plate <NUM> are in communication with the through holes 46a of the feeding and discharging plate <NUM>.

The pillars <NUM> of the first carrier <NUM> are formed as axially extending columns and shaped like a triangle when viewed in the axial direction. The pillars <NUM> are positioned, in the circumferential direction, between the shaft supporting depressions <NUM> of the substrate <NUM>. This means that the pillars <NUM> are arranged at equal intervals in the circumferential direction on the second end 33b of the substrate <NUM>. The diameter of the pitch circle of the pillars <NUM> is substantially the same as the diameter of the pitch circle of the shaft supporting depressions <NUM>.

The pillars <NUM> have flat ends 34a. The ends 34a of the pillars <NUM> are positioned on the same plane as the second end 7d of the first oscillating housing <NUM>. The ends 34a of the pillars <NUM> have an internally threaded portion <NUM> for a reamer bolt.

The internally threaded portion <NUM> has a mating depression 52a and a main body 52b. The mating depression 52a extends in the axial direction from the end 34a of the pillar <NUM> to the axially middle portion of the pillar <NUM>. The main body 52b extends toward the first direction from the bottom of the mating depression 52a. By tightening a reamer bolt (an example of another fastener) <NUM> into the internally threaded portion <NUM>, the first and second carriers <NUM> and <NUM> are integrally assembled together.

The second carrier <NUM> is shaped like a circular plate. The second carrier <NUM> is positioned such that its first end 32a facing the first direction abuts against the ends 34a of the pillars <NUM> forming the first carrier <NUM> and remains in the position. A gap is thus left between the substrate <NUM> of the first carrier <NUM> and the second carrier <NUM>. This gap is sized equally to the height of the pillars <NUM>. This gap is surrounded by the thick portion <NUM> of the first oscillating housing <NUM>, so that an oscillating gear housing part is formed to house the oscillating gear <NUM>.

The first end 32a of the second carrier <NUM> is entirely flat. The second carrier <NUM> has mating holes <NUM> penetrating therethrough in the thickness direction, which are positioned correspondingly to the internally threaded portions <NUM>. Reamer bolts <NUM> are inserted into the mating holes <NUM> through the second carrier <NUM> from the second direction side. By tightening the reamer bolts <NUM> into the main bodies 52b of the internally threaded portions <NUM> via the mating depressions 52a of the pillars <NUM>, the first and second carriers <NUM> and <NUM> are integrally assembled together.

The reamer bolts <NUM> are each divided into a shaft 53a, an externally threaded portion 53b and a head 53c. The externally threaded portion 53b protrudes from the first-direction-side end of the shaft 53a and coaxial with the shaft 53a. The head 53c is formed at the second-direction-side end of the shaft 53a. When the reamer bolts <NUM> are tightened into the internally threaded portions <NUM> designed for the reamer bolts, the shafts 53a of the reamer bolts <NUM> are fitted in the mating depressions 52a of the pillars <NUM> and the mating holes <NUM> of the second carrier <NUM>. In this manner, the shafts 53a of the reamer bolts <NUM> extend across the first and second carriers <NUM> and <NUM>.

The second end 32b of the second carrier <NUM> that faces the second direction has counterboring parts <NUM> that are in communication with the mating holes <NUM>. The counterboring parts <NUM> receive the heads 53c of the reamer bolts <NUM>. This reduces the protruding height of the heads 53c of the reamer bolts <NUM> beyond the second end 32b of the second carrier <NUM>.

The outer peripheral surface 32c of the second carrier <NUM> has a diameter reduced part <NUM> via a step part 56a. The diameter reduced part <NUM> has a smaller outer diameter. An inner race 13b of the second bearing <NUM> is fitted into the diameter reduced part <NUM>. In this manner, the second carrier <NUM> is rotatably supported by the second oscillating housing <NUM> via the second bearing <NUM>.

The diameter reduced part <NUM> has a second-carrier second labyrinth part <NUM>, which is located on the first direction side with respect to the position where the second bearing <NUM> is fitted. The second-carrier second labyrinth part <NUM> has, via a step part 57a, a smaller outer diameter than the diameter reduced part <NUM>. The outer diameter of the second-carrier second labyrinth part <NUM> is slightly smaller than the inner diameter of the second-carrier first labyrinth part <NUM> of the second oscillating housing <NUM>.

The end of the second-carrier second labyrinth part <NUM> is located on the second direction side with respect to the step part 25a of the second-carrier first labyrinth part <NUM>. The second-carrier first labyrinth part <NUM> of the second oscillating housing <NUM> forms the second labyrinth <NUM> in conjunction with the second-carrier second labyrinth part <NUM> of the second carrier <NUM>.

A plurality of (for example, three in this embodiment) shaft supporting holes <NUM> are arranged at equal intervals in the circumferential direction and positioned radially inside the second-carrier second labyrinth part <NUM>. The shaft supporting holes <NUM> rotatably support the crankshafts <NUM> (eccentric rotating members). The shaft supporting holes <NUM> and the shaft supporting depressions <NUM> of the first carrier <NUM> are coaxially arranged. In the shaft supporting holes <NUM>, second bearings 59b are fitted. The second bearings 59b are, for example, plain bearings. The second bearings 59b, however, are not limited to such, and various bearings such as ball bearings can be alternatively used.

The crankshafts <NUM> are rotatably supported in the shaft supporting depressions <NUM> and shaft supporting holes <NUM> via the bearings 59a and 59b. In this manner, the crankshafts <NUM> are slidable and rotatable relative to the shaft supporting depressions <NUM> and shaft supporting holes <NUM> via the bearings 59a and 59b. In the present embodiment, there are three crankshafts <NUM>. The crankshafts <NUM> each have bearing parts 4a and 4b (first bearing part 4a and second bearing part 4b) and a cylindrical eccentric part 4c. The bearing parts 4a and 4b are rotatably supported in the shaft supporting depressions <NUM> and shaft supporting holes <NUM> via the bearings 59a and 59b. The eccentric part 4c is provided between and integrally formed with the bearing parts 4a and 4b.

The axis of rotation of the crankshafts <NUM> (second axis C2) is parallel to the first axis C1. The second axis C2 is also the axes of the bearing parts 4a and 4b. The axial movement of the crankshafts <NUM> is restricted by thrust bearings 61a and 61b (first thrust bearing 61a and second thrust bearing 61b), a first collar 70a and a second collar 70b. The thrust bearings 61a and 61b are outside the bearing parts 4a and 4b in the axial direction. The first collars 70a are provided in the shaft supporting depressions <NUM> of the first carrier <NUM>. The second collars 70b are provided in the shaft supporting holes <NUM> of the second carrier <NUM>. Of the thrust bearings 61a and 61b, the second thrust bearings 61b in the shaft supporting holes <NUM> of the second carrier <NUM> are restricted from moving toward the second direction by retaining rings <NUM> installed in the shaft supporting holes <NUM>.

The axial length of the eccentric part 4c is sized such that the eccentric part 4c can be housed within the axial width of the oscillating gear housing part. Specifically, the axial length of the eccentric part 4c is slightly less than the axial length of the thick portion <NUM> of the first oscillating housing <NUM>. Accordingly, the second-direction-side end of the eccentric part 4c is substantially on the same plane as the first end 8b of the second oscillating housing <NUM>. The axis of the eccentric part 4c (third axis C3) is shifted from the second axis C2 of the crankshaft <NUM>. The eccentric parts 4c rotatably support the oscillating gear <NUM> via third bearings 59c. The third bearings 59c are, for example, plain bearings. The third bearings 59c, however, are not limited to such, and various bearings such as ball bearings can be alternatively used.

The outer diameter of the oscillating gear <NUM> is smaller than the diameter of the inner peripheral surface 10d of the thick portion <NUM>, so that the oscillating gear <NUM> can be accommodated within the oscillating gear housing part. The axial thickness of the oscillating gear <NUM> is equivalent to that of the eccentric parts 4c, for example. Accordingly, the second-direction-side end of the oscillating gear <NUM> is substantially on the same plane as the first end 8b of the second oscillating housing <NUM>. The oscillating gear <NUM> has support holes <NUM> that are positioned correspondingly to the crankshafts <NUM> and through which the eccentric parts 4c of the crankshafts <NUM> extend.

The support holes <NUM> are arranged at equal intervals in the circumferential direction. In the support holes <NUM>, third bearings 59c are provided. The oscillating gear <NUM> is restricted from moving in the axial direction relative to the crankshafts <NUM>, by retaining rings <NUM> provided at the respective axial ends of the third bearings 59c. In this way, the crankshafts <NUM> can allow the oscillating gear <NUM> to rotate only in an oscillatorily manner.

The oscillating gear <NUM> has relief holes <NUM> that are positioned correspondingly to the pillars <NUM> of the first carrier <NUM> and through which the pillars <NUM> extend. The relief holes <NUM> are shaped like a triangle as viewed in the axial direction, so that the shape of the relief holes <NUM> corresponds to the shape of the pillars <NUM>. The relief holes <NUM> are sufficiently larger than the size defined by the outer surface of the pillars <NUM>, so that the pillars <NUM> do not intervene the oscillatory rotation of the oscillating gear <NUM>.

The outer peripheral surface of the oscillating gear <NUM> faces the internal tooth pins <NUM> of the first oscillating housing <NUM> in the radial direction. The outer peripheral surface of the oscillating gear <NUM> has external teeth <NUM> to mesh with the internal tooth pins <NUM>. The number of external teeth <NUM> is different from the number of internal tooth pins <NUM>. For example, in the present embodiment, the number of external teeth <NUM> is <NUM> or smaller by one than the number of internal tooth pins <NUM>. This number is the same as the numbers of feeding and discharging channels <NUM> and <NUM> formed in the first carrier <NUM>.

While oscillatorily rotating, the oscillating gear <NUM> constantly remains in contact with the internal tooth pins <NUM> at a portion between a tooth tip 65a and a tooth root 65b. This roughly creates two working chambers 66a and 66b (first working chamber 66a and second working chamber 66b) between (i) the inner peripheral surface 10d of the thick portion <NUM> of the first oscillating housing <NUM> and (ii) the external teeth <NUM> of the oscillating gear <NUM>. The two working chambers 66a and 66b are line symmetrical to each other when seen in the axial direction. Between the working chambers 66a and 66b, a working chamber 66c is formed. The working chambers 66a and 66b are distinguished from each other according to the pressure during operation. As will be described below, the working chamber 66a refers to a space of high pressure that is in communication with the feeding channels <NUM>, and the working chamber 66b refers to a space of low pressure that is in communication with the discharging channels <NUM>. Accordingly, the working chamber 66c refers to a space of such a pressure that is connected to neither of the feeding channels <NUM> nor the discharging channels <NUM>.

The working chambers 66a and 66b are in communication with the through holes 46a in the feeding and discharging plate <NUM>. Through the through holes 46a, the hydraulic oil can be fed to or discharged from the working chambers 66a and 66b. In this manner, the hydraulic motor <NUM> is rotated.

As shown in <FIG> and <FIG>, the distributor plate <NUM> is sandwiched between the oil distributor <NUM> and the disk <NUM> in the thickness direction. The distributor plate <NUM> is positioned such that its end surfaces <NUM> and <NUM> are respectively in contact with the oil distributor <NUM> and the disk <NUM>. The distributor plate <NUM> has third flow channels <NUM> to <NUM> connecting the first flow channels <NUM> to <NUM> and the feeding and discharging channels (second flow channels) <NUM> and <NUM>. The distributor plate <NUM> is sandwiched between the oil distributor <NUM>, which is a first housing, and the rotatable part <NUM> including the disk <NUM>, which is a second housing, so that the third flow channels <NUM> to <NUM> allow the hydraulic oil (fluid) to branch and merge between the first flow channels <NUM> to <NUM> and the second flow channels <NUM> and <NUM>.

The end surface <NUM> of the distributor plate <NUM> that faces the first direction is in contact with the end surface 45a of the oil distributor <NUM>. The end surface <NUM> of the distributor plate <NUM> that faces the second direction is in contact with the first end 35a of the disk <NUM>. The distributor plate <NUM> can thus preserve tight sealing as the end surfaces <NUM> and <NUM> are pressed by the end surface 45a and the first end 35a. Alternatively, the oil distributor <NUM> and the disk <NUM> may be fastened together to press the distributor plate <NUM> on both sides.

The distributor plate <NUM> has a plurality of through flow channels <NUM>, which serve as the third flow channels. The through flow channels <NUM> extend through the distributor plate <NUM> in the thickness direction and are open at the end surfaces <NUM> and <NUM>. The through flow channels <NUM> are arranged, on the end surfaces <NUM> and <NUM>, along the same circle centered on the axis C1 and next to each other in the circumferential direction. The openings of the through flow channels <NUM> are separated from each other at equal intervals in the circumferential direction. The number of through flow channels <NUM> is equal to the total number of the feeding and discharging channels <NUM> and <NUM>. The through flow channels <NUM> are positioned in correspondence with the pistons <NUM>. In the present embodiment, <NUM> through flow channels <NUM> are arranged next to each other in the circumferential direction.

The openings of the through flow channels <NUM> at the end surface <NUM> face the openings of the first flow channels <NUM> to <NUM> on the end surface 45a of the oil distributor <NUM>. This allows the through flow channels <NUM> to be connected to the first flow channels <NUM> to <NUM>. At the end surface <NUM>, all of the through flow channels <NUM> do not necessarily need to face the first flow channels <NUM> to <NUM>. The openings of the through flow channels <NUM> at the end surface <NUM> face the openings of the feeding and discharging channels <NUM> and <NUM> on the first end 35a of the disk <NUM>. This allows the through flow channels <NUM> to be connected to the feeding and discharging channels <NUM> and <NUM>. At the end surface <NUM>, each of the through flow channels <NUM> faces a corresponding one of the feeding and discharging channels <NUM> and <NUM>.

In addition, the end surface <NUM> of the distributor plate <NUM> has, in the form of grooves, an outer circumferential connecting groove flow channel <NUM>, an inner circumferential connecting groove flow channel <NUM>, outward radial groove flow channels <NUM> and inward radial groove flow channels <NUM>, which all serve as the third flow channels. The outer circumferential connecting groove flow channel <NUM>, inner circumferential connecting groove flow channel <NUM>, outward radial groove flow channels <NUM> and inward radial groove flow channels <NUM> serve as connecting groove flow channels for connecting together the through flow channels <NUM>. The outer circumferential connecting groove flow channel <NUM> is shaped like an annulus along the circumferential direction of the distributor plate <NUM>, and located radially outside the openings of the through flow channels <NUM> on the end surface <NUM>. The outer circumferential connecting groove flow channel <NUM> has the same width and depth along the entire circumference.

The inner circumferential connecting groove flow channel <NUM> is shaped like an annulus along the circumferential direction of the distributor plate <NUM>, and located radially inside the openings of the through flow channels <NUM> on the end surface <NUM>. The inner circumferential connecting groove flow channel <NUM> has the same width and depth along the entire circumference. The outer and inner circumferential connecting groove flow channels <NUM> and <NUM> have the same width and depth. The outer and inner circumferential connecting groove flow channels <NUM> and <NUM> are concentrically arranged around the axis C1.

The outward radial groove flow channels <NUM> extend in the radial direction of the distributor plate <NUM>, so that each outward radial groove flow channel <NUM> connects a predetermined through flow channel <NUM> of the through flow channels <NUM> next to each other in the circumferential direction, to the outer circumferential connecting groove flow channel <NUM>. The inward radial groove flow channels <NUM> extend in the radial direction of the distributor plate <NUM>, so that each inward radial groove flow channel <NUM> connects a predetermined through flow channel <NUM> of the through flow channels <NUM> next to each other in the circumferential direction, to the inner circumferential connecting groove flow channel <NUM>.

Like the end surface <NUM>, the end surface <NUM> of the distributor plate <NUM> also has, as the connecting groove flow channels for connecting together the through flow channels <NUM>, an outer circumferential connecting groove flow channel <NUM>, an inner circumferential connecting groove flow channel <NUM>, outward radial groove flow channels <NUM> and inward radial groove flow channels <NUM>. In the end surfaces <NUM> and <NUM>, the outer and inner circumferential connecting groove flow channels <NUM> and <NUM> have substantially the same shape. Furthermore, the outer and inner circumferential connecting groove flow channels <NUM> and <NUM> in the end surfaces <NUM> and <NUM> are symmetrically arranged in the thickness direction. In the end surfaces <NUM> and <NUM>, the outward and inward radial groove flow channels <NUM> and <NUM> have substantially the same shape. Note that the outward and inward radial groove flow channels <NUM> and <NUM> are differently positioned in the circumferential direction between the end surfaces <NUM> and <NUM>.

In the present embodiment, on the end surface <NUM>, six through flow channels <NUM> are connected to the outer circumferential connecting groove flow channel <NUM> via the outward radial groove flow channels <NUM>. In addition, six through flow channels <NUM> are connected to the inner circumferential connecting groove flow channel <NUM> via the inward radial groove flow channels <NUM>. On the end surface <NUM>, six through flow channels <NUM> are connected to the outer circumferential connecting groove flow channel <NUM> via the outward radial groove flow channels <NUM>. In addition, six through flow channels <NUM> are connected to the inner circumferential connecting groove flow channel <NUM> via the inward radial groove flow channels <NUM>.

The outer circumferential connecting groove flow channel <NUM> formed on the end surface <NUM>, the inner circumferential connecting groove flow channel <NUM> formed on the end surface <NUM>, the outer circumferential connecting groove flow channel <NUM> formed on the end surface <NUM>, and the inner circumferential connecting groove flow channel <NUM> formed on the end surface <NUM> form four separate and individual flow channels, in conjunction with the through flow channels <NUM> connected to these flow channels. These four flow channels provided in the distributor plate <NUM> correspond to the four first flow channels <NUM> to <NUM> formed in the oil distributor <NUM>. <FIG> show how the four independent flow channels in the distributor plate <NUM> correspond to the four first flow channels <NUM> to <NUM>.

Each through flow channel <NUM> is connected to one of the four independent flow channels, specifically, one groove flow channel selected from among (i) one of the inward radial groove flow channels <NUM> formed on the end surface <NUM>, (ii) one of the outward radial groove flow channels <NUM> formed on the end surface <NUM>, (iii) one of the inward radial groove flow channels <NUM> formed on the end surface <NUM>, and (iv) one of the outward radial groove flow channels <NUM> formed on the end surface <NUM>. Each and single through flow channel <NUM> is not connected to two or more of the four independent flow channels, specifically, two or more groove flow channels from among (i) one of the inward radial groove flow channels <NUM> formed on the end surface <NUM>, (ii) one of the outward radial groove flow channels <NUM> formed on the end surface <NUM>, (iii) one of the inward radial groove flow channels <NUM> formed on the end surface <NUM>, and (iv) one of the outward radial groove flow channels <NUM> formed on the end surface <NUM>.

In this manner, adjacent four through flow channels <NUM> of the through flow channels <NUM> that are arranged next to each other in the circumferential direction respectively correspond to the outward and inward radial groove flow channels <NUM> and <NUM> formed on the end surfaces <NUM> and <NUM>, and these adjacent four through flow channels <NUM> form one group. The corresponding orderly arrangement of the outward and inward radial groove flow channels <NUM> and <NUM> on the end surfaces <NUM> and <NUM> is repeated in the circumferential direction. In other words, one inward radial groove flow channel <NUM> formed on the end surface <NUM>, one outward radial groove flow channel <NUM> formed on the end surface <NUM>, one inward radial groove flow channel <NUM> formed on the end surface <NUM>, and one outward radial groove flow channel <NUM> formed on the end surface <NUM> form one group, and the groups of groove flow channels <NUM> and <NUM> are arranged next to each other in the circumferential direction. Alternatively, one inward radial groove flow channel <NUM> formed on the end surface <NUM>, one inward radial groove flow channel <NUM> formed on the end surface <NUM>, one outward radial groove flow channel <NUM> formed on the end surface <NUM>, and one outer radial groove flow channel <NUM> formed on the end surface <NUM> may form one group, and the groups of groove flow channels <NUM> and <NUM> may be arranged next to each other in the circumferential direction. The groups of inward and outward radial groove flow channels <NUM> and <NUM> may be arranged next to each other in the circumferential direction in the opposite direction, in other words, in the clockwise (or counterclockwise) direction when seen in plan view. In this way, a different pattern can be provided.

In the present embodiment, the following features are described as an example. The flow channel <NUM> is connected to the inward radial groove flow channels <NUM> that are formed on the end surface <NUM>. The flow channel <NUM> is connected to the outward radial groove flow channels <NUM> that are formed on the end surface <NUM>. The flow channel <NUM> is connected to the inward radial groove flow channels <NUM> that are formed on the end surface <NUM>. The flow channel <NUM> is connected to the outward radial groove flow channels <NUM> that are formed on the end surface <NUM>. In this way, when the flow channels <NUM> to <NUM> are subject to different pressures, the four independent flow channels can be controlled to be subject to the corresponding pressures.

The openings of the through flow channels <NUM> at the end surface <NUM> are connected to the feeding and discharging channels <NUM> and <NUM> formed in the substrate <NUM> and disk <NUM>, which serve as the second housing <NUM>. Of the four independent flow channels described above, two of the independent flow channels are connected to the feeding channels <NUM>, and the remaining two of the independent flow channels are connected to the discharging channels <NUM>. Note that how the hydraulic oil works will be described below in detail. The following now describes in detail how the hydraulic motor <NUM> works.

The following describes how the hydraulic motor <NUM> works. Hydraulic oil is fed from a hydraulic pump, which is not shown, to the hydraulic motor <NUM>. The hydraulic oil is fed to the feeding channels <NUM> via the flow channels <NUM> and <NUM> of the oil distributor <NUM> and via the distributor plate <NUM>.

Accordingly, as shown in <FIG>, the hydraulic oil fed from the hydraulic pump is delivered through the flow channel <NUM> and flows into the distributor plate <NUM> through the openings at the end surface 45a of the oil distributor <NUM>. After flowing into the distributor plate <NUM>, the hydraulic oil flows, via one or more of the through flow channels <NUM>, through the inward radial groove flow channels <NUM> formed on the end surface <NUM> and then into the inner circumferential connecting groove flow channel <NUM> formed on the end surface <NUM>.

In the distributor plate <NUM>, the hydraulic oil flows through the inward radial groove flow channels <NUM> connected to the inner circumferential connecting groove flow channel <NUM>, to be delivered into different one or more of the through flow channels <NUM>. In the distributor plate <NUM> of the present embodiment, the hydraulic oil can be distributed into five through flow channels <NUM>. After being distributed, the hydraulic oil then flows through these through flow channels <NUM> in the thickness direction of the distributor plate <NUM>, so that the hydraulic oil can be fed to the feeding channels <NUM> via the openings of the through flow channels <NUM> on the end surface <NUM>.

Likewise, as shown in <FIG>, the hydraulic oil fed from the hydraulic pump is delivered through the flow channel <NUM> and flows into the distributor plate <NUM> through the opening at the end surface 45a of the oil distributor <NUM>. After flowing into the distributor plate <NUM>, the hydraulic oil flows into the through flow channels <NUM> through the end surface <NUM> and flow through the through flow channels <NUM> in the thickness direction of the distributor plate <NUM>. The hydraulic oil further flows through the inward radial groove flow channels <NUM> formed on the end surface <NUM> and finally into the inner circumferential connecting groove flow channel <NUM> formed on the end surface <NUM>.

In the distributor plate <NUM>, the hydraulic oil flows through the inward radial groove flow channels <NUM> connected to the inner circumferential connecting groove flow channel <NUM>, to branch into different one or more of the through flow channels <NUM>. In the distributor plate <NUM> of the present embodiment, the hydraulic oil can be distributed into five through flow channels <NUM>. After being distributed, the hydraulic oil is then fed to the feeding channels <NUM> via the openings of these through flow channels <NUM> on the end surface <NUM>.

Through the feeding channels <NUM> and flow channels <NUM> and <NUM>, the hydraulic oil is fed under the same pressure P1. In <FIG> and <FIG>, the hydraulic oil (fluid) is fed at high pressure, which is indicated by the reference sign "P1. " After fed to the feeding channels <NUM>, the hydraulic oil is then fed to the working chambers 66a and 66b via the pistons <NUM> in the feeding openings 41a, the through holes 50c of the sliding plate <NUM>, and the through holes 46a of the feeding and discharging plate <NUM>.

While being energized toward the sliding plate <NUM> by the springs <NUM>, the pistons <NUM> in the feeding openings 41a slide together with the sliding plate <NUM>, which rotates integrally with the first carrier <NUM>. As a result of the rotation of the sliding plate <NUM>, the through holes 50c can be aligned with the pistons <NUM>. When this happens, the hydraulic oil fed to the feeding channels <NUM> flows into the through holes 50c.

The sliding plate <NUM>, which is configured to rotate integrally with the first carrier <NUM>, is slidable together with the feeding and discharging plate <NUM>, which is integrated with the oscillating housing part <NUM>. As a result of the rotation of the sliding plate <NUM> and feeding and discharging plate <NUM>, the through holes 46a can be aligned with the through holes 50c. When this happens, the hydraulic oil fed to the through holes 50c flows into the through holes 46a. When the through holes 46a are not in communication with the through holes 50c, the sliding plate <NUM> closes the through holes 46a and prevents the hydraulic oil from leaking or flowing back through the through holes 46a from the working chambers 66a and 66b.

The number of feeding channels <NUM> (the number of feeding openings 41a and the number of through holes 50c in the sliding plate <NUM> in communication with the feeding openings 41a) is less by one than the number of through holes 46a of the feeding and discharging plate <NUM>. In addition, the number of discharging channels <NUM> (the number of discharging openings 42a and the number of through holes 50c of the sliding plate <NUM> in communication with the discharging openings 42a) is less by one than the number of through holes 46a of the feeding and discharging plate <NUM>. It is thus only the feeding channels <NUM> that are in communication through the through holes 46a of the feeding and discharging plate <NUM> with either one of the two working chambers 66a and 66b. It is only the discharging channels <NUM> that are in communication through the through holes 46a of the feeding and discharging plate <NUM> with the other of the two working chambers 66a and 66b. Here, in the working chamber 66c, the through holes 46a of the feeding and discharging plate <NUM> are not in communication with the through holes 50c of the sliding plate <NUM>. Therefore, the feeding and discharging channels <NUM> and <NUM> are not in communication with the working chamber 66c.

Accordingly, the pressure inside one of the two working chambers 66a and 66b is higher than the pressure inside the other of the two working chambers 66a and 66b. For the sake of simplicity, the following describes a case where the pressure P1 in the working chamber 66a (the left part in <FIG>) is higher than the pressure P2 in the working chamber 66b (the right part in <FIG>). Furthermore, in the following description, the working chamber 66a with the higher pressure P1 will be referred to as the high-pressure working chamber 66a. The working chamber 66b with the lower pressure P2 than the high-pressure working chamber 66a is referred to as the low-pressure working chamber 66b. The high-pressure working chamber 66a is in communication with the feeding channels <NUM>. The low-pressure working chamber 66b is in communication with the discharging channels <NUM>. Through all of the discharging channels <NUM>, the hydraulic oil flows under the same pressure P2. In <FIG> and <FIG>, the hydraulic oil (fluid) is discharged under a low pressure, which is indicated by the reference sign "P2.

As the hydraulic oil is fed to the high-pressure working chamber 66a, the oscillating gear <NUM> is pressed toward the low-pressure working chamber 66b (as indicated by the arrow Y1 in <FIG>). The hydraulic oil is discharged from the low-pressure working chamber 66b through the discharging channels <NUM>. As a result, on the low-pressure working chamber 66b side, the internal tooth pins <NUM> mesh with the external teeth <NUM> of the oscillating gear <NUM>. Here, since the number of external teeth <NUM> is less by one than the number of internal tooth pins <NUM>, the oscillating gear <NUM> is slightly shifted in the rotating direction.

Here, the carrier <NUM> accompanies the oscillating gear <NUM> via the crankshafts <NUM> and is shifted in the rotating direction. In other words, the rotatable part <NUM> is slightly rotated relative to the oscillating housing part <NUM>. The sliding plate <NUM> is then rotated relative to the feeding and discharging plate <NUM>. This changes the state of the communication between the through holes 50c in the sliding plate <NUM> and the through holes 46a of the feeding and discharging plate <NUM>. As the oscillating gear <NUM> oscillatorily rotates, the high-pressure working chamber 66a and the low-pressure working chamber 66b are both slightly shifted in the rotating direction.

Once the state of the communication between the through holes 50c in the sliding plate <NUM> and the through holes 46a of the feeding and discharging plate <NUM> is changed, the hydraulic oil is again fed to the high-pressure working chamber 66a. In addition, the hydraulic oil is discharged from the low-pressure working chamber 66b. As this series of feeding and discharging repeatedly occurs, the rotatable part <NUM> is rotated relative to the oscillating housing part <NUM>. This rotation provides for output.

As a result of the rotation of the sliding plate <NUM> and feeding and discharging plate <NUM>, the through holes 46a can be aligned with the through holes 50c. When this happens, the hydraulic oil is discharged from the low-pressure working chamber 66b into the through holes 50c. When the through holes 46a are not aligned and thus not in communication with the through holes 50c, the sliding plate <NUM> closes the through holes 46a and prevents the hydraulic oil from being discharged through the through holes 46a from the working chambers 66a and 66b.

While being energized toward the sliding plate <NUM> by the springs <NUM>, the pistons <NUM> in the discharging openings 42a of the discharging channels <NUM> slide together with the sliding plate <NUM>, which is configured to rotate integrally with the first carrier <NUM>. As a result of the rotation of the sliding plate <NUM>, the through holes 50c can be aligned with the pistons <NUM>. When this happens, the hydraulic oil discharged through the through holes 46a is discharged into the discharging channels <NUM> via the pistons <NUM> in the discharging openings 42a. The hydraulic oil discharged into the discharging channels <NUM> returns to the tank via the distributor plate <NUM> and via the flow channels <NUM> and <NUM> in the oil distributor <NUM>.

In other words, as shown in <FIG>, the hydraulic oil discharged into the discharging channels <NUM> flows into the distributor plate <NUM> through the openings at the first end 35a of the disk <NUM>. The hydraulic oil then flows into the through flow channels <NUM> through the openings on the end surface <NUM>.

Of the through flow channels <NUM>, the through flow channels <NUM> connected to the outer circumferential connecting groove flow channel <NUM> formed on the end surface <NUM> receive the hydraulic oil flowing from the corresponding discharging channels <NUM>, and the hydraulic oil then flows, via the through flow channels <NUM>, from the outward radial groove flow channels <NUM> on the end surface <NUM> into the outer circumferential connecting groove flow channel <NUM> on the end surface <NUM>. In the distributor plate <NUM>, the hydraulic oil, which merges into the outer circumferential connecting groove flow channel <NUM> at the end surface <NUM>, flows into the through flow channels <NUM> connected to the flow channel <NUM> at the end surface <NUM>. In the distributor plate <NUM> of the present embodiment, the hydraulic oil flows, through the outer circumferential connecting groove flow channel <NUM> on the end surface <NUM>, from five of the through flow channels <NUM> into the through flow channels <NUM> connected to the flow channel <NUM>.

The hydraulic oil then flows through the through flow channels <NUM> in the thickness direction of the distributor plate <NUM>, so that the hydraulic oil can be discharged from the through flow channels <NUM> opening at the end surface <NUM> into the flow channels <NUM> via the openings on the end surface 45a.

Likewise, of the through flow channels <NUM>, the through flow channels <NUM> connected to the outer circumferential connecting groove flow channel <NUM> formed on the end surface <NUM> receive the hydraulic oil flowing from the corresponding discharging channels <NUM>, and the hydraulic oil then flows through the through flow channels <NUM> in the thickness direction of the distributor plate <NUM>. After reaching the end surface <NUM>, the hydraulic oil flows, through the through flow channels <NUM>, from the outward radial groove flow channels <NUM> on the end surface <NUM> into the outer circumferential connecting groove flow channel <NUM> on the end surface <NUM>. In the distributor plate <NUM> of the present embodiment, the hydraulic oil can flow from five of the through flow channels <NUM> into the through flow channels <NUM> connected to the flow channel <NUM>, through the outer circumferential connecting groove flow channel <NUM> on the end surface <NUM>.

In the distributor plate <NUM>, the hydraulic oil, which merges into the outer circumferential connecting groove flow channel <NUM> at the end surface <NUM>, flows into the through flow channels <NUM> connected to the flow channel <NUM> at the end surface <NUM>. The hydraulic oil can then be discharged from the through flow channels <NUM> opening at the end surface <NUM> into the flow channel <NUM> via its opening on the end surface 45a.

Through the discharging channels <NUM> and flow channels <NUM> and <NUM>, the hydraulic oil is discharged under the same pressure P2. In <FIG> and <FIG>, the hydraulic oil (fluid) is discharged at low pressure, which is indicated by the reference sign "P2. " As described, the hydraulic oil, which is discharged from the working chamber 66b through the discharging channels <NUM>, merges in the distributor plate <NUM> and is then discharged into the flow channels <NUM> and <NUM>.

As described above, the hydraulic motor <NUM> makes use of the difference between the number of feeding channels <NUM> (the number of feeding openings 41a and the number of through holes 50c in the sliding plate <NUM> in communication with the feeding openings 41a) and the number of through holes 46a in the feeding and discharging plate <NUM>, and the difference between the number of discharging channels <NUM> (the number of discharging openings 42a and the number of through holes 50c in the sliding plate <NUM> in communication with the discharging openings 42a) and the number of through holes 46a in the feeding and discharging plate <NUM>, such that the state of the communication between the through holes 50c in the sliding plate <NUM> and the through holes 46a in the feeding and discharging plate <NUM> is sequentially changed in the circumferential direction. In this way, the hydraulic oil is selectively fed to and discharged from the working chambers 66a and 66b through the through holes 46a in the feeding and discharging plate <NUM>, so that the rotatable part <NUM> rotates.

The carrier <NUM>, which constitutes the rotatable part <NUM>, is divided into the first carrier <NUM> and the second carrier <NUM>. The first and second carriers <NUM> and <NUM> are fixedly coupled together using the reamer bolts <NUM>. Therefore, power is transmitted between the first carrier <NUM> and the second carrier <NUM> through the reamer bolts <NUM>. The shafts 53a of the reamer bolts <NUM> extend across the first and second carriers <NUM> and <NUM>. When compared with the case where the externally threaded parts 53b extend across the first and second carriers <NUM> and <NUM>, the power transmission can be more efficiently performed between the first carrier <NUM> and the second carrier <NUM>.

The hydraulic oil fed to the working chambers 66a and 66b leak into the microgaps between the carriers <NUM> and <NUM> and the crankshafts <NUM> via the microgaps between the crankshafts <NUM> and the oscillating gear <NUM>. The leaked hydraulic oil is discharged through the shaft supporting depressions <NUM> formed in the first carrier <NUM> into the drain passage <NUM> (tank channel). The hydraulic oil discharged into the drain passage <NUM> (tank channel) returns to the tank (not shown).

On the first-direction side of the oscillating gear <NUM>, the third labyrinth <NUM> is formed by the first outer peripheral surface 33d and the second end 33b of the first carrier <NUM> and the plate labyrinth part <NUM> of the feeding and discharging plate <NUM>. On the second-direction side of the oscillating gear <NUM>, the second labyrinth <NUM> is formed by the second-carrier first labyrinth part <NUM> of the second oscillating housing <NUM> and the second-carrier second labyrinth part <NUM> of the second carrier <NUM>. In this way, the hydraulic oil may leak from the working chambers 66a and 66b through the microgaps between the crankshafts <NUM> and the oscillating gear <NUM>, but hardly leak through the space between the first oscillating housing <NUM> and the first carrier <NUM> and through the space between the second oscillating housing <NUM> and the second carrier <NUM>.

In the hydraulic motor <NUM>, since the oscillating housing part <NUM> is stationary, the output can be provided by the rotatable part <NUM>. In this case, it is an external device fixedly attached to the outer flange part <NUM> of the rotatable part <NUM> (first carrier <NUM>) that is to be rotated. Alternatively, the rotatable part <NUM> may be stationary, and the output can be provided by the oscillating housing part <NUM>. In this case, it is an external device fixedly attached to the outer flange part <NUM> of the oscillating housing part <NUM> (first oscillating housing <NUM>) that is to be rotated.

The hydraulic motor <NUM> has the internal tooth pins <NUM> in the first oscillating housing <NUM>. The rotatable part <NUM> includes the carrier <NUM>, the crankshafts <NUM> rotatably supported by the carrier <NUM>, and the oscillating gear <NUM>. The oscillating gear <NUM> is configured to oscillatorily rotate in response to the rotation of the crankshafts <NUM> and to mesh with the internal tooth pins <NUM>. With such configurations, the hydraulic motor <NUM> can be rotated by feeding the hydraulic oil into and discharging the hydraulic oil from the working chambers 66a and 66b formed between the inner peripheral surface 7c of the first oscillating housing <NUM> and the outer peripheral surface of the oscillating gear <NUM>. The rotation of the hydraulic motor <NUM> can produce high rotational torque. To constitute the above-described hydraulic motor <NUM>, the oscillating housing part <NUM>, which is constituted by separate parts, can be suitably used.

The hydraulic motor <NUM> has the feeding and discharging plate <NUM> for selectively feeding the hydraulic oil to or discharging the hydraulic oil from the working chambers 66a and 66b. The feeding and discharging plate <NUM> is located at the first end 10b of the thick portion <NUM>, which is one of the ends of the oscillating gear <NUM> that faces the first direction). The feeding and discharging plate <NUM> is fixedly attached to the first oscillating housing <NUM> using the bolts <NUM>. The bolts <NUM> used to secure the first and second oscillating housings <NUM> and <NUM> are also used to secure the feeding and discharging plate <NUM>. This can successfully reduce the number parts constituting the hydraulic motor <NUM>.

In the hydraulic motor <NUM> of the above-described embodiment, the hydraulic oil is fed from a hydraulic pump to the oil distributor <NUM>, delivered through the flow channels <NUM> and <NUM>, distributed by the distributor plate <NUM> into the feeding channels <NUM>, and then fed to the working chambers 66a and 66b. The hydraulic oil is discharged from the working chambers 66a and 66b through the discharging channels <NUM>, merged in the distributor plate <NUM> and then discharged into the flow channels <NUM> and <NUM>.

According to the hydraulic motor <NUM>, the distributor plate <NUM> has the through flow channels <NUM> connecting together the end surfaces <NUM> and <NUM> and the connecting groove flow channels <NUM> to <NUM> formed as grooves on the end surfaces <NUM> and <NUM>. These third flow channels <NUM> to <NUM> are tightly sealed since the end surface 45a of the oil distributor <NUM>, which is the first housing, tightly abut the end surface <NUM> and the first end 35a of the disk <NUM>, which is the second housing, tightly abut the end surface <NUM>. This facilitates the flow of the hydraulic oil (fluid) in the distributor plate <NUM>. The distributor plate <NUM> thus connects the first flow channels <NUM> to <NUM> and the second flow channels <NUM> and <NUM>. With such configurations, the distributor plate <NUM> can allow the hydraulic oil (fluid) to branch and merge between the first flow channels <NUM> to <NUM> and the second flow channels <NUM> and <NUM>, which are larger in number than the first flow channels <NUM> to <NUM>.

In this way, in the first and second directions, it is only the thickness of the distributor plate <NUM> that is required to cause the hydraulic oil to branch and merge between the first flow channels <NUM> to <NUM> and the second flow channels <NUM> and <NUM>. Therefore, when compared with the conventional art described above, the size of the hydraulic motor <NUM> can be reduced in the direction extending along the first axis C1. This means that, with the size remaining the same, the hydraulic motor <NUM> can produce increased output torque. Alternatively, with the output torque remaining the same, the hydraulic motor <NUM> can be reduced in size in the direction extending along the first axis C1, thereby saving the required space.

The distributor plate <NUM> has the connecting groove flow channels <NUM> to <NUM> on the front and rear end surfaces <NUM> and <NUM>. In this way, at most, four independent flow channels can be formed to allow the hydraulic oil to branch and merge. This allows for a first-speed operation according to which the hydraulic oil is fed from one flow channel <NUM> to the feeding channels <NUM> and a second-speed operation according to which the hydraulic oil is fed from the two flow channels <NUM> and <NUM> to the feeding channels <NUM>.

While the hydraulic motor <NUM> employs the first-speed operation, the hydraulic oil is discharged from the discharging channels <NUM> to the single flow channel <NUM>. While the hydraulic motor <NUM> employs the second-speed operation, the hydraulic oil is discharged from the discharging channels <NUM> into the two flow channels <NUM>. Thus, there is no restriction to be imposed on the amount of oil to be discharged. In addition, the end surfaces <NUM> and <NUM> have the connecting groove flow channels <NUM> to <NUM> formed therein, and tightly sealed flow channels can be formed simply by sandwiching the connecting groove flow channels <NUM> to <NUM> between two parts. This can provide for significantly improved sealing, when compared with the conventional technique where the grooves are formed on the circumferential surface.

In the distributor plate <NUM>, the through flow channels <NUM> arranged next to each other in the circumferential direction are spaced away from each other at equal intervals on the end surfaces <NUM> and <NUM>. In this way, the through flow channels <NUM> can be connected to the feeding and discharging channels <NUM> and <NUM>, which are alternately arranged in the circumferential direction in orbital motors.

In the distributor plate <NUM>, the outer and inner circumferential connecting groove flow channels <NUM> and <NUM> each connect more than one of the through flow channels <NUM>. With such configurations, independent flow channels can be formed with selected ones of the through flow channels <NUM> at predetermined positions simply by processing a flat disk such that the through flow channels <NUM> extend through the flat disk and annular grooves are formed on the flat end surfaces to serve as the outer and inner circumferential connecting groove flow channels <NUM> and <NUM>. Therefore, branching and merging can be easily accomplished even if the independent flow channels are subject to different pressures.

As noted, the distributor plate <NUM> having the above features can be easily manufactured simply by cutting flat disks or through casting. In addition, since the distributor plate <NUM> can remain highly reliably sealed by being sandwiched between the first and second housings, the end surfaces <NUM> and <NUM> do not need to be subject to very accurate machining.

In the distributor plate <NUM>, each through flow channel <NUM> can be selectively connected to one of the outer and inner circumferential connecting groove flow channels <NUM> and <NUM>, since it is determined in advance which one of the outward and inward radial groove flow channels <NUM> and <NUM> is connected to each through flow channel <NUM>. In this way, independent flow channels can be formed for branching and merging of the hydraulic oil.

It should be particularly noted that the outward and inward radial groove flow channels <NUM> and <NUM> are connected to adjacent ones of the through flow channels <NUM> that are arranged next to each other in the circumferential direction. Therefore, the distributor plate <NUM> is compatible with the second housing in which the feeding and discharging channels <NUM> and <NUM> under different pressures are adjacent to each other, and can accomplish branching and merging between the flow channels <NUM> to <NUM> and the feeding and discharging channels <NUM> and <NUM>.

Alternatively, the outward and inward radial groove flow channels <NUM> and <NUM> are connected to every other ones of the through flow channels <NUM> that are arranged next to each other in the circumferential direction. Therefore, of the feeding and discharging channels <NUM> and <NUM> subject to different pressures, the distributor plate <NUM> can establish connection between the flow channels <NUM> and <NUM> and the feeding channels <NUM> subject to a higher pressure for branching and merging. Furthermore, the distributor plate <NUM> can establish connection between the flow channels <NUM> and <NUM> and the discharging channels <NUM> subject to a lower pressure for branching and merging.

In the above-described manner, depending on where the outward and inward radial groove flow channels <NUM> and <NUM> are formed, branching and merging flow channels can be freely designed between the flow channels. In other words, the four independent flow channels can be freely designed and connected to the second flow channels simply by determining where the outward and inward radial groove flow channels <NUM> and <NUM> are formed.

In this case, the outward and inward radial groove flow channels <NUM> and <NUM> are connected to four adjacent ones of the through flow channels <NUM> that are arranged next to each other in the circumferential direction, and these four through flow channels <NUM> form one group. The corresponding orderly arrangement of the outward and inward radial groove flow channels <NUM> and <NUM> is repeated in the circumferential direction. In this way, the four independent flow channels can be freely designed and connected to the second flow channels. The outward and inward radial groove flow channels <NUM> and <NUM> are connected to two adjacent ones of the through flow channels <NUM> that are arranged next to each other in the circumferential direction, and these two through flow channels <NUM> form one group. The corresponding orderly arrangement of the outward and inward radial groove flow channels <NUM> and <NUM> is repeated in the circumferential direction. In this way, two independent flow channels can be freely designed on one of the end surfaces <NUM> and <NUM> of the distributor plate <NUM>, and connected to the second flow channels.

In the above-described embodiment, the bolts <NUM> are used as fixture parts for fixedly attaching together the first and second oscillating housings <NUM> and <NUM>. The reamer bolts <NUM> are used as fixture parts for fixedly attaching together the first and second carriers <NUM> and <NUM>. The present embodiment, however, is not limited to such, and any parts can be used in place of the bots <NUM> and reamer bolts <NUM> as long as they can secure the oscillating housings <NUM> and <NUM> and the carriers <NUM> and <NUM>. For example, rivets and the like may be used as the fixture parts.

In the above-described embodiment, the bolts <NUM> are used to secure the feeding and discharging plate <NUM> onto the first oscillating housing <NUM>. The present embodiment, however, is not limited to such, and different fixture members than the bolts <NUM> can be used to secure the feeding and discharging plate <NUM> onto the first oscillating housing <NUM>. The feeding and discharging plate <NUM> does not need to be co-tightened with the first and second oscillating housings <NUM> and <NUM>. If such is the case, each of the oscillating housings <NUM> and <NUM> may have, on the outer peripheral surface thereof, an outer flange part for securing the oscillating housings, and the oscillating housings <NUM> and <NUM> may be formed intro a single piece by securing the outer flange parts using bolts.

In the above-described embodiment, the rotatable part <NUM> has three crankshafts <NUM>, and these crankshafts <NUM> are used to restrict the rotation of the oscillating gear <NUM> to oscillatory rotation. The present embodiment, however, is not limited to such, and the rotatable part <NUM> can be configured in any manner as long as it has at least one crankshaft <NUM>. In this case, the second axis C2 of the crankshaft <NUM> is aligned with the first axis C1 of the rotatable part <NUM>. In other words, a center crankshaft is employed. The center crankshaft restricts the rotation of the oscillating gear <NUM>.

Claim 1:
A fluid device (<NUM>) comprising:
a first housing (<NUM>) having one or more first flow channels (<NUM> to <NUM>);
a second housing (<NUM>, <NUM>, <NUM>, <NUM>) having second flow channels (<NUM> and <NUM>) that are larger in number than the first flow channels (<NUM> to <NUM>); and
a distributor plate (<NUM>) having a third flow channel connecting a predetermined one of the first flow channels (<NUM> to <NUM>) and corresponding ones of the second flow channels (<NUM> and <NUM>),
wherein the distributor plate (<NUM>) is sandwiched between the first housing (<NUM>) and the second housing (<NUM>, <NUM>, <NUM>, <NUM>) in a thickness direction of the distributor plate (<NUM>) such that end surfaces (<NUM> and <NUM>) of the distributor plate (<NUM>) are in contact respectively with the first and second housings (<NUM> and <NUM>, <NUM>, <NUM>, <NUM>),
characterized in that the third flow channel includes:
a plurality of through flow channels (<NUM>) arranged next to each other in a circumferential direction, the through flow channels (<NUM>) opening at the end surfaces (<NUM> and <NUM>); and
one or more connecting groove flow channels (<NUM>, <NUM>, <NUM>, <NUM>) extending in the circumferential direction, the connecting groove flow channel (<NUM>, <NUM>, <NUM>, <NUM>) connecting together more than one of the through flow channels (<NUM>).