This invention relates to power transmission and particularly to power transmission of the type comprising fluid pressure energy translating devices which may function as a pump of a fluid motor.
Background and Summary of the Invention
A common type of fluid pressure energy translating device comprises a housing which contains a rotating group of the axial piston type such as shown in U.S. Pat. Nos. 2,776,628, 3,457,873 and 3,481,277.
In devices of this type, a rotating group is mounted in a cavity of a housing and comprises a rotary cylinder barrel in the cavity which is driven or drives a shaft and has a plurality of axial cylinders in which pistons are positioned. The ends of the pistons are connected to shoes which engage an inclined surface and the cylinders communicate through openings with an inlet or outlet in a valve plate positioned adjacent and engaging the cylinder barrel. As the barrel rotates, the fluid is either pumped into or out of the cylinders depending upon whether the device is being used as a pump or motor.
In the maintenance of such a device, it is necessary to take the device apart and replace the various components such as the cylinder barrel, pistons, shoes and associated seals. Handling of the separate parts is costly and time consuming.
Among the objectives of the present invention are to provide a fluid pressure energy translating device which will permit rapid field replacement of the rotating components and seals; which utilizes a cartridge containing the rotating parts and seals which may be readily removed and replaced by a new cartridge; which cartridge can readily be engaged with a drive shaft rotatably mounted in a housing and located within the cavity of the housing.
In accordance with the invention, the fluid pressure energy translating device comprises a housing defining a cavity, a drive shaft having a portion thereof rotatably mounted in the housing and extending into the cavity. The cavity has an open end remote from said drive shaft. A valve block closes the open end of said housing. A rotating group cartridge is positioned in the cavity between the valve block and is drivingly engaged with the shaft. The cartridge comprises a valve plate engaging the valve block and an angle block. A rotatable cylinder barrel is interposed between the valve plate and angle block in abutment with the valve plate and in driving relation with the drive shaft. The cylinder barrel has a plurality of piston cylinders, each of which has a port for communicating the cylinders with a face of the valve plate, a piston in each said cylinder, shoes connected to the pistons and engaging an inclined surface on the angle block and means interconnecting the valve plate and angle block to form a removable cartridge.
Description of the Drawings
FIG. 1 is a fragmentary longitudinal part sectional view of a fluid pressure energy translating device embodying the invention.
FIG. 2 is an end view taken from the left as viewed in FIG. 1.
FIG. 3 is a fragmentary sectional view taken along the line 3--3 in FIG. 2.
FIG. 4 is a sectional view on an enlarged scale of the cartridge with a retainer rod.
FIG. 5 is a partly diagrammatic view showing the manner in which a cartridge may be replaced.
FIG. 6 is a part sectional view of the container and cartridge package that can be used in handling and shipping the cartridge.
Description
Referring to FIGS. 1-5, the pressure energy translating device embodying the invention comprises a housing 10 that is adapted to be positioned in the end of an electric motor 11, where the device is a pump, or in a comparable housing of a drive shaft, where the device is to be operated as a motor.
The device further includes a valve block 12 closing the open end of a chamber or cavity 13 in the housing. A shaft 14 from the housing 11 is journalled by a bearing 15 in an opening in the end of the housing 10 and extends into the cavity 13.
In accordance with the invention, a rotating group cartridge 16 is interposed between the valve block 12 and the end wall 17 of the housing 10.
As shown in FIGS. 3 and 4, the end block 12 includes spaced openings 18, 19 which may function as an inlet or outlet, depending upon the direction of rotation of the rotating group in the cartridge 16, as is well known in the art.
Referring to FIG. 4, the cartridge 16 comprises a valve plate 21, an angle block 22 having an inclined surface 23 and a tubular casing 24 interconnecting the valve plate 21 and angle block 22. A cylinder barrel 25 is provided and includes a plurality of axial cylinders 26 in which pistons 27 are mounted and have their outer ends 27a formed with spherical surfaces engaging shoes 28 which are retained against the angular surface 23 by retainer 29, as is well known in the art. A spring 30 is provided and urges the cylinder barrel 25 against the valve plate 21. The operation of the rotating group as a pump or motor is in a well known manner as shown in the aforementioned U.S. patents, which are incorporated herein by reference.
A pin 31 extends radially from the angle block 22 through an axially elongated opening 32 in the casing 24 so that there is limited permissible movement axially between the casing 24 and the angle block 22 and an undulating spring 33 is interposed between the casing 24 and a flange 34 on the angle block 22. An O-ring 35 is provided on a flange 36 of the valve plate 21 and O-ring 38 is provided in a groove 38 on the periphery of the angle block 22. Finally, the cartridge includes a radial shaft seal 39 which is held in position in a recess 40 by a snap ring 41 to provide a seal for the shaft 14. An annular sealing ring 42 in a groove in the end face of housing 10 provides a seal with valve block 12. A removable plastic rod S is provided in the cartridge 16 to maintain the parts in alignment before the cartridge 16 is used.
When it is desired to replace the cartridge 16, the valve block 12 is removed by loosening and removing bolts 43 so that the cartridge subassembly can be removed and replaced by a new cartridge subassembly.
The cartridge 16 is preferably handled and stored by placement in a container C filled with clean oil and closed by a suitable closure, the oil being of the type utilized in the hydraulic system.
The steps to be followed are as follows:
1. The old cartridge is removed from the housing.
2. The new cartridge is removed from its sealed container and inserted into the housing (shaft seal end first).
3. Before the angle block bottoms in the housing, the cartridge is rotated back and forth until a hole in the angle block 22 engages a locating pin 46 in the housing 10; and then the cartridge is pressed in firmly.
4. As the cartridge is inserted (step 3), the drive shaft extension 14 pushes the shipping rod S out of the cartridge and engages the cylinder barrel 24.
5. The valve block 12 is replaced by engaging locating pin 45 in hole 44 of the valve plate, and then bolted to the housing 10. As the bolts 43 are tightened, the valve block 12 presses against the valve plate 21 which forces the spring loaded tube against the angle block. This ensures positive sealing of the angle block against the housing.
6. The hydraulic fittings are replaced. The case is filled with clean oil which is provided in the cartridge container.
7. The unit is now ready to operate.
Among the advantages offered by the construction are the following:
1. Economical design due to minimum of parts required.
2. Higher overall efficiency of operation because of common drive shaft, resulting in fewer bearings and no coupling shaft.
3. Lower replacement cost since the housing and valve block are not routinely replaced.
4. All wear parts are replaced by exchange of the cartridge.
5. All seals are replaced by exchange of the cartridge.
6. Does not require special tools or technological training to service.