摘要:
In a pump or fluid motor (11, 11a, 11b) having a closed chamber (57) in which cylinders (38) orbit and reciprocate, leakage and cooling fluid which accumulates in the chamber (57) is formed into a rotating annular volume by centrifugal effects and exhibits a higher pressure in the region where the cylinders (38) move radially inward and closer together than in the opposite region where the cylinders (38) move outward and further apart. Power wastage from drag torque, turbulence and heat generation is reduced by scavenging the accumulated fluid from the chamber (57). Internal recirculation of the scavenged fluid from the high pressure portion of the annular rotating volume back to the low pressure portion is avoided by communicating the drain passages (68, 68a, 68b) with only a limited relatively high pressure sector of the rotating volume of fluid.
摘要:
An apparatus and method is provided for producing a piston assembly for use in a fluid translating device such as a hydraulic pump or motor. In the subject arrangement, a piston is provided having a cavity at one end thereof and a slipper having a spherical head portion which is precisely positioned within the cavity to provide a space therearound and subsequent thereto a plastic material is formed in the space to maintain the spherical head portion in the cavity. This arrangement eliminates the sliding friction that exists in other piston assemblies and furthermore reduces the precise sizing of the cavity relative to the spherical head portion.
摘要:
Hydraulic piston pumps and motors are used in various applications to power implements, steering, propel, and auxiliary systems. However, it is important to keep the piston weight and compressible fluid volume low in order to have a smaller more efficient pump. The subject piston is manufactured in a simple manner to achieve a reliable, light weight design. The piston has a cylindrical body having an outer surface. The piston is manufactured by forming a first bore having a large diameter in the body extending from the outer surface and terminating at an annular shoulder. A second bore is formed which extends from the annular shoulder to a predetermined depth. A tube is inserted through the bore and extends a predetermined distance into the second bore. A cap has a bore and is positioned on the body in abutment with at least a portion of the outer surface. The cap slidably receives the tube through the bore. The cap is brazed to the body and the tube is brazed to the cap and to the body to form an isolated annular cavity in the piston.
摘要:
A fluid device has an inlet and a pumping chamber which is positioned in spaced relation to the inlet. The chamber is rotatably movable relative to the inlet. Apparatus is provided for contacting the fluid at the inlet at a preselected angle sufficient for accelerating the fluid into the chamber.
摘要:
The invention is concerned with an improvement in a control system for a hydrostatic drive of a vehicle comprising a pair of hydrostatic pumps the output of each of which is adjustable by moving an arm attached to a servo valve controlling the displacement of said pumps, each pump powering a respective hydraulic motor which drives a respective ground engaging means of said vehicle. The improvement of the present invention mechanically controls the speed and steering functions of the system. It comprises a pair of adjusting means, one communicating with each of the pumps, each comprising a frame adjacent the pump, a first crank mounted centrally to the frame, a first end of the first crank drivingly linked to the arm; a second crank mounted centrally to the frame, a first end of the second crank drivingly linked to a second end of the first crank and a third crank mounted centrally to the frame, a first end of the third crank drivingly linked to the second end of the first crank and a second end of the third crank drivingly linked to steering linkage means. The improved arrangement further includes tying means drivingly mounted adjacent a second end of each of the second cranks linking movement thereof.
摘要:
A method is provided for producing a piston assembly adapted for use in a hydraulic pump or motor and having an overall length shorter than previously known piston assemblies while maintaining a strong mechanical connection and a high, efficient volumetric output. The method includes the steps of forming a slipper with a spherical ball on one end; forming a piston having a body portion and a connecting portion, the connecting portion having a spherical bottom surface, a groove spaced from the bottom surface and a contoured portion having an angled outer surface and an inner surface; inserting the spherical ball into the cavity; forcing the contoured portion inwardly to place the inner surface into contact with the spherical ball and to substantially longitudinally align the outer surface of the piston body with the angled surface of the contoured portion; heat treating the piston to a predetermined hardness and depth; and finishing the total longitudinal length of the piston to a finished size.
摘要:
Axial piston fluid translating units commonly experience undesirable shaft deflections and barrel tilting during operation. A fluid translating unit includes a barrel plate interposed the end of a barrel and a porting surface defined within a housing thereof. The barrel plate is axially spaced from an end of the barrel and is in face sealing engagement with the porting surface. The barrel plate defines a plurality of fluid ports, each communicating between one of a plurality of barrel cylinder bores and the porting surface. In one aspect a plurality of counterbores are provided in the barrel in surrounding relation to the fluid ports. A plurality of seal rings having a sealing end defining an annular seal face of a predetermined width for face sealing engagement with the barrel plate. The seal rings are each disposed in one of the counterbores in circumferential sealing relation of a predetermined length which is no greater than the width of the sealing face. A plurality of annular springs are disposed in the counterbores for urging the seal rings into sealing engagement with the other of the barrel and the barrel plate. This arrangement permits tilting of the barrel without damaging contact or excessive leakage between the barrel plate and the porting surface.
摘要:
The design and construction of seals located between a cylinder barrel and a barrel plate rotatable therewith for axial piston fluid translating units have caused an increase in overall unit size, increased stiffness between the barrel and barrel plate and an increase in manufacturing cost and complexity. The present invention overcomes these problems by providing an axially compact, combined circumferential and axial face seal means. The seal means includes an annular seal ring having a sealing end and a biasing end with the sealing end defining an annular seal face of a predetermined width. A biasing means is attached to the biasing end of the seal ring and includes a spring ring having a generally flat base plate with a plurality of resilient fingers angularly extending therefrom. The axially compact structure of the seal means of this invention provides the required flexibility between the barrel and barrel plate while reducing overall unit size, and cost and complexity of manufacturing.
摘要:
Variable displacement axial piston pumps are useful in outputting pressurized fluid to operate fluid actuators. The currently available center pivoted variable displacement axial piston pumps waste energy by compressing trapped volumes of oil during operation. The present variable displacement axial piston pump has first and second opposite sides of a swash plate pivotally connected to a pump housing by a pair of off-center pivots with the angle of the swash plate being controlled by first and second actuators connected to the opposite sides of the swash plate. Each of the off-center pivots includes a pair of pivot pins connected to the housing and releasably pivotally seated in a pair of semi-cylindrical pockets formed in the opposite sides of the swash plate. The first actuator at the first side of the swash plate holds the semi-cylindrical pocket seated against the pivot pin while the second actuator controls pivotal movement of the swash plate about the first off-center pivot. The off-center pivots are preferably located such that the trapped volume of oil is minimized and remains substantially constant between the minimum and maximum displacement settings of the swash plate.
摘要:
Electro-hydraulic valve arrangements are useful in controlling a displacement control member of a variable displacement pump or motor. However, previous digital electro-hydraulic valves having brief pulse widths required special high speed solenoids to speed up the response time of the valve and resulted in increased cost of the valve. The subject digital electro-hydraulic valve arrangement includes a pair of on/off solenoid actuated valves arranged in series so that a flow path is initiated by a first of the valves and is disrupted by the second valve. The response times of the valves are equal such that directing an electrical signal to the second valve during the response time of the first valve results in extremely brief pulse widths of the valve arrangement. Using two solenoid actuated valves in this manner permits the use of less costly solenoid valves to provide very brief pulse widths through the total valve arrangement.