Expansible chamber devices – Relatively movable working members – Interconnected with common rotatable shaft
Reexamination Certificate
2000-02-25
2001-09-04
Thorpe, Timothy S. (Department: 3746)
Expansible chamber devices
Relatively movable working members
Interconnected with common rotatable shaft
C091S499000, C060S478000
Reexamination Certificate
active
06283009
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a swash plate type hydraulic unit for use as a swash plate type hydraulic pump and a hydraulic motor, and particularly, to an improvement of a swash plate type hydraulic unit comprising a cylinder block having a large number of cylinder bores arranged annularly in parallel with a cylinder block axis on a pitch circle which surrounds the axis; a large number of plungers slidably fitted respectively in the cylinder bores; and a plunger swash plate for rotating relatively with respect to the cylinder block, thereby causing the plungers to reciprocate.
PRIOR ART
In the above conventional swash plate type hydraulic unit, cylinder bores are formed in a solid cylinder block (see, for example, Japanese Patent Application Laid-open No. 63-203959).
However, since cylinder bores with plungers slidably fitted therein are fairly deep, a long time is required for forming them in the solid cylinder block, and this point is an obstacle to mass production of the hydraulic unit.
The present invention has been accomplished in view of the above-mentioned circumstances and it is an object of the invention to provide the foregoing swash plate type hydraulic unit in which a cylinder block having a large number of cylinder bores can be obtained efficiently, and moreover, even if the shapes of ports formed in the cylinder bores are complicated, the ports can easily be formed.
DISCLOSURE OF THE INVENTION
For achieving the above-mentioned object, according to the present invention, there is proposed a swash plate type hydraulic unit comprising a cylinder block having a large number of cylinder bores arranged annularly in parallel with a cylinder block axis on a pitch circle which surrounds the said axis; a large number of plungers slidably fitted respectively in the cylinder bores; and a plunger swash plate for rotating relatively with respect to the cylinder block, thereby causing the plungers to reciprocate, characterized in that the cylinder block is formed by combining a plurality of block plates with one another, the block plates being divided at split planes extending orthogonal to the cylinder block axis; the cylinder bores are comprised of inlet holes for supporting corresponding plungers slidably and inner holes of a diameter larger than that of the inlet holes, the inlet holes being formed in an inlet-side one of the block plates positioned on a side which faces the plunger swash plate, the inner holes being formed in remaining inner-side ones of the block plates positioned on the side opposite to the plunger swash plate to each define an oil chamber between the inner hole and the outer peripheral surface and end surface of the corresponding plunger; the cylinder block has positioning means for coaxially arranging the cylinder bores in the block plates, and the cylinder block is provided with a plurality of valve holes having distributing valves mounted therein; and ports of the respective cylinder bores are formed in groove shapes in the split plane of a part of the block plates so as to be controlled selectively by the distributing valves.
According to this feature, since many inlet holes or inner holes formed in the block plates are relatively shallow, the mass production of the block plates having such a large number of holes is easy, and therefore by combining such block plates with one another while positioning them with use of positioning means, there can be obtained the cylinder block efficiently. In this case, even if there is a slight error in machining or assembly, such an error can be absorbed by the difference in diameter between the inlet holes and the inner holes of a diameter larger than that of the inlet holes, so causes no obstacle to the sliding motion of each plunger. This means that even if the inner hole machining accuracy is made rough, it is possible to decrease the percent defective of products and make contribution to a further improvement of mass-productivity.
Besides, in each of the inner holes, since there is formed an oil chamber to which not only the inner end surface of the associated plunger but also the outer peripheral surface thereof faces, the sliding surface of the plunger can always be maintained in a state of satisfactory lubrication by the hydraulic oil present in the oil chamber.
Moreover, the ports of the cylinder bores which are controlled selectively by the distributing valves are formed in groove shapes in the split plane of a part of the block plates. Therefore, even if the ports are of complicated shapes, they can easily be formed, thereby enhancing the productivity of the cylinder block in cooperation with the inlet holes and inner holes of each of the cylinder bores being easily formed.
In addition to the above feature, there is proposed a swash plate type hydraulic unit characterized in that a large number of valve holes are formed through the plural block plates annularly in parallel with the cylinder block axis on a pitch circle separate from and concentric with the foregoing pitch circle, spool type distributing valves are slidably fitted in the valve holes, a valve swash plate is arranged to reciprocate relatively with respect to the cylinder block thereby causing the associated distributing valves to reciprocate and the valve swash plate and the associated plunger swash plate are disposed on the same slant plane and are formed integrally with each other to form a swash plate assembly, and the ports of the respective cylinder bores are disposed so as to be controlled selectively by the distributing valves at positions out of phase by 90° in the circumferential direction of the cylinder block with respect to the cylinder pores.
According to this feature, since the ports of each of the cylinder bores are formed so as to be controlled selectively by the associated distributing valves at positions out of phase by 90° in the circumferential direction of the cylinder block with respect to the cylinder bores, it becomes possible to dispose both the plunger swash plate and valve swash plate on the same slant plane and the production of a swash plate assembly having both the swash plates becomes easy.
In addition to the above feature, if positioning pins are inserted into a series of positioning holes formed axially in all of the block plates, thereby forming the positioning means, and the block plates are bonded together with solder, and the block plates and the positioning pins are also bonded together with solder, the positioning of the block plates with respect to one another can be done easily and accurately. Besides, since solder is applied not only between adjacent block plates but also between the positioning pin and the associated block plate, the bonding between adjacent block plates can be strengthened by the positioning pin.
In addition to the above feature, if annular grooves capable of holding a solder material therein are formed in the outer peripheries of the plural block plates which are axially superimposed together so as to face the split planes of the block plates, prior to the bonding, the solder material can be placed easily and accurately at positions which face the split planes of the block plates on the outer peripheries of the block plates. Therefore, when the solder material is heat-melted, they can be penetrated between adjacent bonding surfaces positively without waste.
Further, in addition to the above feature, if the thickness of each of the block plates is set to a value which permits press working for the plate, each of the block plates can be subjected to press working and hence it is possible to further enhance the mass-productivity.
REFERENCES:
patent: 2231100 (1941-02-01), Wahlmark
patent: 2955475 (1960-10-01), Zubaty
patent: 4950132 (1990-08-01), Brian, Jr. et al.
patent: 5528976 (1996-06-01), Ikeda et al.
patent: 54-15503 (1979-02-01), None
patent: 63-203959 (1988-08-01), None
patent: 7-167041 (1995-07-01), None
patent: 9-151839 (1997-06-01), None
patent: 11-82672-A (1999-03-01), None
Hayashi Tsutomu
Nakajima Yoshihiro
Okuzaki Hideo
Takahashi Masako
Arent Fox Kintner & Plotkin & Kahn, PLLC
Honda Giken Kogyo Kabushiki Kaisha
Solak Timothy P.
Thorpe Timothy S.
LandOfFree
Swash plate type hydraulic unit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Swash plate type hydraulic unit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Swash plate type hydraulic unit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2473623