Patents by Inventor Yoshizumi Nishimura

Yoshizumi Nishimura has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6681794
    Abstract: A spool 33 provided with a flange 39 is inserted in a spool bore 32, and a pressing force of a spring 52 is always applied through the flange 39 to the spool 33 at its one end in a second pressure chamber 35. A fluid groove 60 is formed in an inner peripheral surface of the spool bore 32 at a position near an abutment surface 51. A hydraulic fluid under the same pressure P2 as that in the second pressure chamber 35 is introduced to the fluid groove 60 through a fluid passage 61 formed in a valve body 31. When the flange 39 and the abutment surface 51 are in contact with each other, the hydraulic fluid is allowed to enter the interface between them through the fluid groove 60. A rise of the cracking pressure, which occurs upon the flange coming into tightly close contact with the abutment surface, can be prevented without reducing the strength of the flange 39, and stable opening/closing characteristics of the spool 33 can be achieved.
    Type: Grant
    Filed: January 17, 2002
    Date of Patent: January 27, 2004
    Assignee: Hitachi Construction Machinery Co., Ltd.
    Inventors: Mitsuhisa Tougasaki, Yoshizumi Nishimura, Yusaku Nozawa, Kinya Takahashi
  • Publication number: 20030102027
    Abstract: A spool 33 provided with a flange 39 is inserted in a spool bore 32, and a pressing force of a spring 52 is always applied through the flange 39 to the spool 33 at its one end in a second pressure chamber 35. A fluid groove 60 is formed in an inner peripheral surface of the spool bore 32 at a position near an abutment surface 51. A hydraulic fluid under the same pressure P2 as that in the second pressure chamber 35 is introduced to the fluid groove 60 through a fluid passage 61 formed in a valve body 31. When the flange 39 and the abutment surface 51 are in contact with each other, the hydraulic fluid is allowed to enter the interface between them through the fluid groove 60. A rise of the cracking pressure, which occurs upon the flange coming into tightly close contact with the abutment surface, can be prevented without reducing the strength of the flange 39, and stable opening/closing characteristics of the spool 33 can be achieved.
    Type: Application
    Filed: January 17, 2002
    Publication date: June 5, 2003
    Inventors: Mitsuhisa Tougasaki, Yoshizumi Nishimura, Yusaku Nozawa, Kinya Takahashi
  • Publication number: 20020134078
    Abstract: To permit forcedly stopping combining flows of pressure fluid from two hydraulic pumps when a load pressure on a combined-flow-driven actuator in which the flows of pressure fluid are combined together exceeds a predetermined pressure and hence to permit driving the combined-flow-driven actuator with the pressure fluid from only one of the hydraulic pumps, a hydraulic drive system is provided with a flow-combining valve 2 connected to a directional control valve 1 in a first group of directional control valves via a center bypass passage 3, a flow-combining circuit 5 communicating the flow-combining valve 2 and a supply port of a flow-combining directional control valve 4 with each other, and a combined-flow-driven actuator 20 controlled by the flow-combining directional control valve 4, and performs overall power control such that a total value of input torques to the two hydraulic pumps 15,18 does not exceed an output torque from an engine 30.
    Type: Application
    Filed: December 4, 2001
    Publication date: September 26, 2002
    Inventors: Kinya Takahashi, Yoshizumi Nishimura, Yusaku Nozawa, Mitsuhisa Tougasaki
  • Patent number: 6453585
    Abstract: To permit forcedly stopping combining flows of pressure fluid from two hydraulic pumps when a load pressure on a combined-flow-driven actuator in which the flows of pressure fluid are combined together exceeds a predetermined pressure and hence to permit driving the combined-flow-driven actuator with the pressure fluid from only one of the hydraulic pumps, a hydraulic drive system is provided with a flow-combining valve 2 connected to a directional control valve 1 in a first group of directional control valves via a center bypass passage 3, a flow-combining circuit 5 communicating the flow-combining valve 2 and a supply port of a flow-combining directional control valve 4 with each other, and a combined-flow-driven actuator 20 controlled by the flow-combining directional control valve 4, and performs overall power control such that a total value of input torques to the two hydraulic pumps 15,18 does not exceed an output torque from an engine 30.
    Type: Grant
    Filed: December 4, 2001
    Date of Patent: September 24, 2002
    Assignee: Hitachi Construction Machinery Co., Ltd.
    Inventors: Kinya Takahashi, Yoshizumi Nishimura, Yusaku Nozawa, Mitsuhisa Tougasaki
  • Patent number: 6438952
    Abstract: A hydraulic circuit system having a load sensing system including a hydraulic pump, a plurality of hydraulic actuators driven by a hydraulic fluid delivered from the hydraulic pump, a plurality of control valves disposed between the hydraulic pump and the plurality of acutators, a signal detecting hydraulic line to which a signal pressure based on a maximum load pressure among the plurality of hydraulic actuators is introduced, and pump control means for controlling a delivery pressure of the hydraulic pump to be held higher than the signal pressure by a predetermined value.
    Type: Grant
    Filed: October 24, 2000
    Date of Patent: August 27, 2002
    Assignee: Hitachi Construction Machinery Co., Ltd.
    Inventors: Yusaku Nozawa, Mitsuhisa Tougasaki, Yoshizumi Nishimura, Kinya Takahashi
  • Patent number: 6422009
    Abstract: A fixed throttle 12 is provided in a delivery line 11a of a fixed pump 11 driven by an engine 9 for rotation together with a hydraulic pump 1, and a differential pressure detecting valve 31 is provided in association with the fixed throttle 12 to detect a differential pressure across the fixed throttle 12 and to output a pressure lower than the detected differential pressure by a predetermined value. The output of the differential pressure detecting valve 31 is introduced, as a signal pressure, to a pressure bearing section 5c of a load sensing valve 5, thereby setting a target differential pressure. With that arrangement, a pressure in link with an engine revolution speed can be directly employed as the set differential pressure of the load sensing valve, and the structure of the load sensing valve can be avoided from being complicated.
    Type: Grant
    Filed: January 23, 2001
    Date of Patent: July 23, 2002
    Assignee: Hitachi Construction Machinery Co., Ltd.
    Inventors: Yusaku Nozawa, Mitsuhisa Tougasaki, Yoshizumi Nishimura, Kinya Takahashi
  • Patent number: 6408876
    Abstract: It is an object of the present invention to provide a control valve which can reduce the number of external lines connected to a hydraulic remote control valve. A control valve 1 for controlling hydraulic cylinders 2,2′ is provided, in one 26 of spool covers, with fluid passages 27,27′, a shuttle valve 28 for selecting higher one of pilot pressures to be transmitted to these fluid passages 27,27′, and a fluid passage 29 for transmitting the pressure selected by the shuttle valve 28. The fluid passages 27,27′ are in communication with pressure fluid ports 25,25′ as connection ports for pilot lines 24a,24c. The control valve 1 is also provided, in the other spool cover 32, with fluid passages 33,33′, a shuttle valve 34 for selecting higher one of pilot pressures to be transmitted to these fluid passages 33,33′, and a fluid passage 35 for transmitting the pressure selected by the shuttle valve 34.
    Type: Grant
    Filed: October 13, 2000
    Date of Patent: June 25, 2002
    Assignee: Hitachi Construction Machinery Co., Ltd.
    Inventors: Yoshizumi Nishimura, Yusaku Nozawa, Kinya Takahashi, Mitsuhisa Tougasaki
  • Patent number: 6378302
    Abstract: A hydraulic line slit 20 formed in a valve body 50 of a flow distribution valve 5-1, a control chamber 70, and a hydraulic line 31-1 are connected to a signal transmitting hydraulic line 9. A lap portion 32 is formed in the hydraulic line slit 20, the lap portion 32 having a check valve function with a lap amount X when the valve body 50 is in a cutoff position. A 2-position, 3-way valve 11 is disposed in the hydraulic line 31-1. The valve 11 connects the control chamber 70 of the flow distribution valve 5-1 to only the signal transmitting hydraulic line 9 when an external signal F is not applied, and to both the signal transmitting hydraulic line 9 and a lower-pressure detecting hydraulic line 35, which is connected an outlet passage 5b of a flow distribution valve 5-2 on the side of a hydraulic actuator 3-2, when the external signal F is applied.
    Type: Grant
    Filed: October 31, 2000
    Date of Patent: April 30, 2002
    Assignee: Hitachi Construction Machinery Co., Ltd.
    Inventors: Yusaku Nozawa, Mitsuhisa Tougasaki, Yoshizumi Nishimura, Kinya Takahashi
  • Patent number: 6327959
    Abstract: A recovery check valve 26 and a piston valve 27 are axially slidably disposed within a spool 2 in coaxial relation. An axial fluid passage 32 is formed within a cylindrical portion 27a of the piston valve 27, and a seat portion 33 for the recovery check valve is formed at an open end of the cylindrical portion 27a. The cylindrical portion 37a of the piston valve is formed with a hole 36 through which a hydraulic fluid in the fluid chamber 32 is introduced to a bridge passage 21 when the spool 2 is operated so as to introduce a hydraulic fluid from a hydraulic pump to the bottom side of a hydraulic cylinder. Fluid passages 40, 31 are formed within the spool so that a hydraulic fluid in the bridge passage 21 is introduced to the closed end of the piston valve through the fluid passages when the spool is operated in the opposite direction. With such a structure, the size of the valve apparatus can be set to the same size as the directional control valve not provided with the recovery check valve.
    Type: Grant
    Filed: July 13, 2000
    Date of Patent: December 11, 2001
    Assignee: Hitachi Construction Machinery
    Inventors: Kinya Takahashi, Yoshizumi Nishimura, Yusaku Nozawa, Nobuhiko Ichiki, Mitsuhisa Tougasaki
  • Patent number: 6135149
    Abstract: Pressure compensating valves disposed at inlet sides of directional control valves are each configured with a step-shaped spool having a larger diameter portion and smaller diameter portions and pressure receiving chambers are provided to sandwich the larger diameter portion such that a pump delivery pressure and an inlet pressure of a metering throttle of the directional control valve acts in the chambers, respectively, and further pressure receiving chambers are provided at respective ends of the smaller diameter portions such that an outlet pressure of the metering throttle and a signal pressure act in the chambers, respectively. A check valve operated by the outlet pressure of the metering throttle is fitted in the smaller diameter end portion positioned on the side of the pressure receiving chamber to reduce the pump delivery pressure and produce a signal pressure.
    Type: Grant
    Filed: August 11, 1999
    Date of Patent: October 24, 2000
    Assignee: Hitachi Construction Machinery Co., Ltd.
    Inventors: Yusaku Nozawa, Yoshizumi Nishimura, Nobuhiko Ichiki, Minoru Aoki, Kinya Takahashi
  • Patent number: 5957159
    Abstract: A pair of directional control valves 8 and a pair of hold check valves 9 are disposed respectively between a pair of metering notches 6, which are formed in a land 4-1 of a spool 2 and have functions of both flow rate control and direction control, and a pair of actuator ports A, B. Each hold check valve comprises a valve body 90 in the form of a hollow spool having a seat portion 12 formed on an outer periphery and being subject to a pressure developed in an outlet passage 10 communicating with one of the actuator ports to act in the valve-closing direction. Each flow distribution valve comprises a valve body 80 being slidably fitted in the valve body 90 and having a front surface positioned to face an inlet passage 7 communicating with the metering notch and a rear surface positioned to face an control pressure chamber 30 communicating with a signal detecting hydraulic line.
    Type: Grant
    Filed: September 17, 1998
    Date of Patent: September 28, 1999
    Assignee: Hitachi Construction Machinery Co., Ltd.
    Inventors: Kinya Takahashi, Yoshizumi Nishimura, Yusaku Nozawa, Nobuhiko Ichiki, Minoru Aoki