Toyoda Koki Kabushiki Kaisha

Toyota Jidosha Kabushiki Kaisha

Tsuneo Tanaka

Kyosuke Haga

Yoshiharu Inaguma

Keiichi Nakamura

Toshifumi Sakai

Harunori Shiratori

Katsuhisa Mori

Tatsuya Yamamoto

Makoto Kawahara

In a vane pump, a pump housing assembly contains a cam ring having an internal cam surface. A rotor carrying plural vanes is disposed within the cam ring and rotated by a drive shaft. Both end surfaces of the cam ring contact with a pair of flat contact surfaces formed within the pump housing assembly, respectively, and the vanes define plural pump sectors between the rotor and the cam ring, together with the rotor, the cam ring and the pair of contact surfaces. The contact surfaces are formed with a pair of intake ports and a pair of exhaust ports. Furthermore, one of the contact surfaces is provided with a pair of pressure leaking grooves formed at locations between the intake ports and the exhaust ports. The locations of the pressure leaking grooves are chosen so as to leak fluid in pump sectors communicating with the exhaust ports to adjacent pump sectors communicating with the intake ports through passages formed by the pressure leaking grooves and the side edges of vanes located between the two pump sectors whenever the instantaneous pressure of the fluid in the exhaust ports approaches an instantaneous maximum pressure. With this operation, the instantaneous maximum pressure is decreased, thereby the amplitude of the pressure pulsation being reduced.

Vane pump with pressure leaking groove to reduce pulsations

A rotary servovalve includes a valve sleeve formed with a supply port for connection to a source of fluid under pressure and distribution ports respectively for connection to opposite fluid chambers of a hydraulic power cylinder, the valve sleeve being formed at the inner periphery thereof with circumferentially spaced sleeve channels respectively in open communication with the supply and distribution ports, and a valve rotor coupled with the valve sleeve for relative rotation thereto, the valve rotor being formed thereon with circumferentially spaced control lands which are arranged to correspond with the sleeve channels when the servovalve is in a neutral position. The control lands corresponding with the sleeve channels in open communication with the distribution ports are each formed larger in width than the corresponding sleeve channel and smaller in height than the control land corresponding with the sleeve channel in open communication with the supply port to define a predetermined clearance for restricting the flow of fluid discharged from and supplied into the distribution ports when the servovalve is in the neutral position.

Rotary servovalve for power-assisted steering system

A control system for a hydraulic tandem pump assembly including a primary pump for supplying fluid under pressure to a power-assisted steering device and a secondary pump for supplying fluid under pressure to a hydraulic motor of an engine cooling fan, which pumps are mounted on a common drive shaft for rotation therewith. The control system includes an electrically operated flow quantity control valve disposed within a communication passage between the secondary pump and the hydraulic motor to bypass fluid under pressure discharged from the secondary pump into an inlet passage connecting a fluid reservoir to the secondary pump, a temperature sensor arranged to detect an ambient temperature of a prime engine of the vehicle for producing therefrom an output signal indicative of the ambient temperature, and an electric control apparatus connected to the sensor to control an electric current applied to the control valve in response to the output signal from the sensor in such a manner that the control valve is conditioned to bypass a large part or the entirety of fluid under pressure discharged from the secondary pump into the inlet passage when the ambient temperature of the engine is below a predetermined value.

Control system for hydraulic tandem pump in motor vehicle

In a vane pump, a pump housing contains a cam ring having an internal cam surface, in which a rotor carrying eight vanes is rotatable by a drive shaft. A pair of side plates positioned in the receiving bore in contact engagement with the opposite end surface of the cam ring, the internal cam surface and the rotor define a pump chamber. Each of the side plates is formed at its inside surface contacting the cam ring with a pair of intake ports, a pair of exhaust ports and a vane back pressure groove. This groove is always filled with pressurized fluid supplied from the exhaust ports such that the pressurized fluid is directed into vane support slits formed in the rotor. The angular width between the start point of each of the intake ports and the start point of one of the exhaust ports is chosen to an angle of 90 degrees which is twice the pitch of the vanes, and the angular width of each of the exhaust ports is chosen to be not larger than or angular width which outer end surfaces of two successive vanes make, whereby the volume of pressurized fluid which leaks from the vane back pressure groove towards the intake ports through a clearance between the rotor and each side plate can be maintained constant.

Vane pump

A rotary servovalve includes a valve sleeve and a rotor relatively rotatably fitted therein, and includes a pressure control section composed of lands angularly spaced from each other when the servovalve is in a neutral condition and a pressure characteristic adjusting section composed of lands disposed in overlapping relation to each other when the servovalve is in the neutral condition. The lands of the pressure control section have first chamfers for gradually reducing the area of communication between fluid supply and discharge passages as the valve sleeve and the rotor are relatively turned, and the lands of the pressure characteristic adjusting section have second and third chamfers for gradually increasing and then gradually reducing the area of communication between the fluid supply and discharge passages as the valve sleeve and the rotor are relatively turned. The second and third chamfers, and the first chamfers are effectively combined for pressure control to provide desired valving characteristics.

Rotary servovalve

A rotary servovalve for a power steering system is provided wherein a plurality of orifices are established by a plurality of axial extending lands formed on the internal surface of a valve sleeve and the circumferential surface of a rotor received therein. As the rotor rotates relative to the sleeves, the orifices control the pressure and the flow of fluid supplied from a pump to a power cylinder of the steering system and from the power cylinder to a reservoir. Each of the lands on the rotor is formed at each of its circumferential edges with a chamfer which has a third slope for preventing the generation of cavitation and hissing noise, in addition to first and second slopes for offering an optimum steering feeling to a vehicular driver.

A rotary valve for a power steering system includes a valve sleeve in which a rotor is rotatably carried for controlling fluid flow from a supply pump to a cylinder of the power steering system. A plurality of lands are formed on the outer periphery of the rotor, at least three of which have the same configuration. A plurality of lands are formed on the inner periphery of the valve sleeve, at least two of which have the same configuration to thereby vary the areas of two orifices formed between the three lands of the rotor and the two lands of the valve sleeve at the same rate during relative rotation therebetween. Further, the edge portions of the three lands of the rotor are formed with two longitudinally curved slopes so as to provide an optimum two-step valving characteristic. Furthermore, two of lands formed on the rotor have at each side edge portion thereof a longitudinaly curved and radially extending wall so as to form additional orifice areas to provide an optimum valving characteristic by combining the same with the above two orifice areas.

Growing community of inventors

Okazaki, Japan

Tsuneo Tanaka