Hydraulic devices that include a hydraulic motor and a brake assembly typically include large housings and/or complicated drive connections. An example of a known hydraulic motor and brake assembly includes a seal that blocks fluid flow between the brake assembly and the hydraulic motor. Accordingly, the known assembly includes a large housing having at least three fluid ports: two fluid ports for the motor and one fluid port for the brake This construction requires a larger housing and a complicated fluid path.
Another known motor and brake assembly includes a gerotor motor of the type having a spool valve that connects to a main output drive shaft. The output end of the main output drive shaft is disposed on one side of the rotor assembly and the spool valve and brake assembly are disposed on an opposite side of the gerotor assembly. Such a configuration requires complicated attachment of the spool valve to the main output drive shaft and a portion of the main output drive shaft orbits and rotates. Furthermore, the spool valve includes an extension to which brake disks are attached, thus requiring a larger housing assembly for the hydraulic device.
A hydraulic device that includes a hydraulic motor and a brake assembly that overcomes the aforementioned shortcomings includes a compact housing assembly and fewer complicated fluid paths as compared to the known previously discussed assemblies. An embodiment of a hydraulic device includes a housing, an output shaft a rotor assembly, a wobble shaft, and a brake assembly. The housing includes a central opening, a fluid inlet passage, and a fluid outlet passage. The housing at least partially defines a pressurizable brake chamber in fluid communication with the inlet passage. The output shaft is received in the central opening of the housing and extends from the housing. The rotor assembly includes a stator and a rotor having cooperating teeth defining fluid pockets. The rotor rotates and orbits relative to the stator when hydraulic fluid is directed toward the fluid pockets. The fluid pockets are in communication with the fluid inlet passage and the fluid outlet passage. The wobble shaft connects to the rotor and to the output shaft to rotate the output shaft upon rotational and orbital movement of the rotor. The brake assembly includes first brake disks, second brake disks, a piston, and a biasing member. The first brake disks connect to the output shaft The second brake disks connect to the housing. The piston contacts at least one of the brake disks. The biasing member urges the piston to an operating condition braking the output shaft. The output shaft can include a knurled outer surface.
According to another embodiment, a hydraulic device includes a gerotor assembly, a wobble stick, an output shaft, a housing assembly, a first port in the housing assembly, a second port in the housing assembly, first brake disks, second brake disks, a piston, and a biasing member The gerotor assembly includes a rotor and a stator. The wobble stick connects at a first end to the rotor. The output shaft connects to a second end of the wobble stick. The housing assembly receives the gerotor assembly, the wobble stick and the output shaft. The first port is in communication with the gerotor assembly. The second port is also in communication with the gerotor assembly. The first brake disks connect to the output shaft. The second brake disks connect to the housing assembly. The piston is disposed in the housing assembly adjacent at least one of the brake disks. The piston cooperates with the housing assembly to define a brake pressure chamber. The housing assembly and the first and second ports are configured such that pressurization of either port results in pressurization of the brake pressure chamber. The biasing member is disposed in the housing and contacts the piston The biasing member urges the piston toward at least one of the brake disks.
According to another embodiment, a spool valve-type hydraulic device includes a housing, a spool valve disposed in the housing, a gerotor assembly cooperating with the spool valve, and a spring applied/pressure released brake assembly cooperating with the spool valve and the housing. The housing defines first and second ports. The spool valve includes a portion extending axially from the housing having an output end configured to connect to an associated device such as a wheel or a motor. The gerotor assembly communicates with the first and second ports. Pressurization of either port results in the spring applied/pressure released brake assembly operating in a disengaged position which allows for rotation of the spool valve.
The aforementioned hydraulic devices can include mechanisms to allow for the pressurization of the brakes and/or brake assemblies that were described above to operate in a disengaged position to allow for rotation of the hydraulic motor while the hydraulic motor is not receiving fluid through either of the inlet or outlet ports. The aforementioned hydraulic devices can also include knurled surfaces to promote the formation of fluid coated bearing surfaces.
The hydraulic device described below includes a hydraulic motor and a brake assembly. The device provides a small brake package that can inhibit the motor from rotating when the motor is in an unpressurized condition. The brake assembly can be disengaged when pressure is delivered to either port of the motor.
With reference to
A rotor assembly 22 connects to the rear housing section 14. In the depicted embodiment, the rotor assembly 22 is similar to a known gerotor assembly that includes a stator 24 and a rotor 26. The rotor 26 includes a plurality of teeth that cooperate with the stator 24 in a known manner to define expanding fluid pockets and contracting fluid pockets as the rotor rotates and orbits relative to the stator when hydraulic fluid is directed toward the expanding pockets.
A wobble stick 30, also referred to as a drive link or a wobble shaft, connects to the rotor 26 at a first end 32. The wobble stick 30 can attach to the rotor 26 via a splined connection, which is known in the art. The first end 32 of the wobble stick 30 rotates and orbits relative to the stator 24 as the rotor 26 rotates and orbits relative to the stator. A second end 34 of the wobble shaft 30 connects to an output shaft 40.
The output shaft 40 includes a central opening 42 aligned along its rotational axis 44. The wobble stick 30 attaches to the output shaft 40 via a splined connection, which is known in the art. Orbital movement of the rotor 26 relative to the stator 24 is translated into rotational movement of the output shaft 40 about its rotational axis 44.
A wear plate 50 is sandwiched between the rear housing section 14 and the rotor assembly 22. The wear plate 50 includes a plurality of openings 52 radially spaced from the rotational axis 44 of the output shaft 40. The openings 52 in the wear plate 50 communicate with the cells (either expanding or contracting) formed in the rotor assembly in a manner that is known in the art. Accordingly, the number of openings 52 equals the number of cells.
An end plate 56 attaches to the gerotor assembly 22 on an opposite side of the gerotor assembly as the wear plate 50. In the depicted embodiment, the end plate 56 closes the housing assembly for the moveable components of the device 10.
When the hydraulic device 10 operates as a motor, rotation of the output shaft 54 is caused by delivering pressurized fluid to the expanding cells of the rotor assembly 20. The hydraulic device 10 can also operate as a pump when the output shaft 40 is driven by an external power device, for example a gasoline or diesel engine. A first port 60 (depicted schematically) communicates with a fluid source (not shown) and a first annular groove 62 formed in the rear housing section 14 via a passage 64 (depicted schematically). The first annular groove 62 extends radially outward from and directly communicates with a central opening 66 formed in the rear housing section 14 that receives the output shaft 40.
With reference to
With reference back to
Fluid enters the pockets in the rotor assembly 22 via the openings 52 in the wear plate 50 on one side of the line of eccentricity of the rotor assembly and exits the rotor assembly via openings 52 in the wear plate 50 on the opposite side of the line of eccentricity. A second annular groove 82 formed in the rear housing section 14 communicates with the second set of axial slots 72 (
With reference back to
The brake assembly for the device will be described in more detail. With reference to
In the depicted embodiment, a piston 110 contacts one of the friction disks 104. Alternatively, the piston 110 can contact one of the disk stampings 106 if the orientation was slightly changed. A seal 112 contacts the piston 110 and the front housing section 12 thus separating the brake chamber 100 from a cavity 114 that receives a biasing member, for example a spring 116, that urges the piston 110 towards the friction disk 104. When the brake chamber 100 is unpressurized the spring 116 urges the piston 110 towards the friction disk 104 and the friction disks contact the disk stampings 106 thereby inhibiting the rotation of the output shaft 40.
With reference to
A thrust bearing assembly 130, which in the depicted embodiment includes two washers having a thrust bearing sandwiched between them, surrounds the output shaft 40 at a location that is aligned with the radial passage 122 of the output shaft 40. A seal retainer 132 that retains a seal 134 fits around the output shaft outside of the thrust bearing assembly 130. A dust cover 136 fits around the output shaft 40 to protect the seal 134 and other internal components. The seal 134 cooperates with the front housing section 12, the seal retainer 132 and the output shaft 40 to define a boundary of the brake chamber 100.
Pressurized fluid passes through the thrust bearing assembly 130, which can act as a sort of miniature pump, to pressurize the brake chamber 100. When pressurized, the fluid acts on the piston 110 urging it away from the friction disks 104.
The hydraulic device 10 can be a “bearingless” device in that the depicted embodiment does not include bearings, other than the thrust bearing assembly 130. With reference to
The knurled sections are disposed along the output shaft 40 at locations that contact, or are adjacent, bearing surfaces of the housing assembly. In the depicted embodiment, the left-hand most knurled section 140a extends from the splined section 102 on the output shaft 40 to adjacent a portion of the output shaft 40 that is radially aligned with a third annular groove 142, which will be described in more detail below. A second knurled section 140b extends between the third annular groove 142 and the first annular groove 62. A third knurled section 140c extends between the first annular groove 62 and the opening of the angled passage 80 The fourth knurled section 140d extends between the opening of the angled passage 80 and the second annular groove 82. The fifth knurled section 140c extends between the second annular groove 82 and the end of the output shaft 40. The knurled sections need not be located exactly where they have been described; however, in the depicted embodiment portions of the output shaft have not been knurled to facilitate valving, e.g. the section between 140c and 140d, or because the central opening 42 of the output shaft 40 is ball checked to pressure
That the central opening 42 of the output shaft 40 is ball checked to pressure is one reason for the third annular groove 142, which is axially spaced from the first and the second annular grooves 62 and 82, respectively. Since the central opening 42 is typically under pressure when the device 10 is operating, the third annular groove 142 allows the output shaft 40 to expand under pressure exerted from inside the central opening. If desired, the third annular groove 142 can be ball checked to low pressure, i.e. the port that is acting as the outlet for the device, to facilitate cooling of the output shaft 40 and other components of the device. Likewise, the cavity 114 that receives the spring 116 can also be ball checked to low pressure, if desired, to also facilitate cooling.
With reference to
With respect to the lower portion of the embodiment depicted in
A compact hydraulic motor and brake assembly has been described. Modifications and alterations will occur to those upon reading and understanding the preceding detailed description. The invention is not limited to only the embodiments disclosed above. lnstead, the invention is broadly defined by the appended claims and the equivalents thereof.