Patents by Inventor Yohei Katayama

Yohei Katayama 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).

  • Publication number: 20140291088
    Abstract: The present invention provides a shock absorber having improved performance and durability. A damping force generation mechanism 30a includes a spring member 106a. The spring member 106a includes radially extending spring portions 117 having high spring constants and circumferentially extending spring portions 118 having low spring constants. The respective radially extending spring portions 117 and the respective circumferentially extending spring portions 118 are integrally configured so that respective biasing forces thereof act dynamically linearly. Further, an annular stepped portion 74, which limits strokes of the respective circumferentially extending spring portions 118, is provided on an opposite end side cylindrical wall portion 71 of a pilot body 49.
    Type: Application
    Filed: March 21, 2014
    Publication date: October 2, 2014
    Applicant: HITACHI AUTOMOTIVE SYSTEMS, LTD.
    Inventors: Yohei KATAYAMA, Hiroki OHARA, Sadatomo MATSUMURA
  • Patent number: 8800729
    Abstract: During either of the extension and compression strokes, hydraulic liquid flows from a cylinder upper chamber into a reservoir through an annular passage and a damping force control mechanism, and a damping force is generated by the damping force control mechanism. The check valve is provided with a sub-check valve in parallel thereto, which opens in a very low piston speed region to allow the hydraulic liquid to flow through an orifice passage. These check valves are opened successively as the piston speed increases, thereby generating a sufficiently small damping force in the very low piston speed region during the compression stroke of the piston rod, and obtaining a moderate damping force when the piston speed increases.
    Type: Grant
    Filed: March 19, 2012
    Date of Patent: August 12, 2014
    Assignee: Hitachi Automotive Systems, Ltd.
    Inventors: Hiroyuki Yabe, Yohei Katayama, Takashi Nezu
  • Patent number: 8794400
    Abstract: A damping force adjustable hydraulic shock absorber, in which response delay of a pressure control valve and self-excited vibration of a valve body can be prevented. A damping force is generated by controlling an oil flow between an annular oil passage (21) and a reservoir (4) generated by sliding movement of a piston in a cylinder with use of a back-pressure type main valve (27) and a pressure control valve (28). The damping force is directly generated by the pressure control valve, and valve-opening pressure of the main valve is adjusted by adjusting an inner pressure of a back-pressure chamber. In the pressure control valve, a valve spring is disposed between a valve body and a plunger. A mass of the valve body is sufficiently less than that of the plunger, and a spring stiffness of the valve spring is higher than that of a plunger spring.
    Type: Grant
    Filed: March 31, 2009
    Date of Patent: August 5, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Takao Nakadate, Takashi Nezu, Yohei Katayama, Shigeo Katayama, Hiroyuki Yabe
  • Patent number: 8798859
    Abstract: [Object] The present invention provides a suspension control apparatus that allows miniaturization of a solenoid valve. [Solution] When a controller is started up by a power source controller (a power source unit), the controller switches a control current from 0 ampere to a maximum current value I6 at the same time as the startup. After that, the control shifts to normal control. As a result, even if a hysteresis of a damping force characteristic is large relative to the control current, it is possible to promptly move a solenoid valve to a position to be used in the normal control.
    Type: Grant
    Filed: January 31, 2012
    Date of Patent: August 5, 2014
    Assignee: Hitachi Automotive Systems, Ltd.
    Inventors: Toru Uchino, Ryusuke Hirao, Yohei Katayama, Hiroyuki Yabe, Hiroki Ohara
  • Patent number: 8651252
    Abstract: A frequency-dependent mechanism provided at the lower end of a piston rod includes a tubular housing displaceable in an inner tube, together with the piston rod as one unit, and further includes a free piston and O-rings. A shutter of a passage area varying mechanism is provided with an axially extending inner hole, orifices, and oil grooves. The opening area between oil holes 3C and the orifices 33B is changed according to the rotational position of the shutter. The opening area between oil holes 3D and 3E and the oil grooves 33C and 33D and the opening area between oil holes 3F and 3G and the oil grooves 33E and 33F are also variably adjusted according to the rotational position of the shutter.
    Type: Grant
    Filed: December 28, 2011
    Date of Patent: February 18, 2014
    Assignee: Hitachi Automotive Systems, Ltd.
    Inventors: Yohei Katayama, Takao Nakadate, Kenji Noda, Mikio Yamashita, Fumiyuki Yamaoka
  • Publication number: 20130275003
    Abstract: [Object] The present invention provides a suspension control apparatus that allows miniaturization of a solenoid valve. [Solution] When a controller is started up by a power source controller (a power source unit), the controller switches a control current from 0 ampere to a maximum current value I6 at the same time as the startup. After that, the control shifts to normal control. As a result, even if a hysteresis of a damping force characteristic is large relative to the control current, it is possible to promptly move a solenoid valve to a position to be used in the normal control.
    Type: Application
    Filed: January 31, 2012
    Publication date: October 17, 2013
    Inventors: Toru Uchino, Ryusuke Hirao, Yohei Katayama, Hiroyuki Yabe, Hiroki Ohara
  • Patent number: 8544619
    Abstract: A fluid pressure shock absorber in which valve opening of the main valve is controlled by an inner pressure of a backpressure chamber. A first piston (3) and a second piston (4) coupled to a piston rod (10) are fitted in a cylinder (2) such that a piston chamber (2C) is defined between the first and second pistons. An extension-side main valve (18) and a compression-side main valve (23) are provided in the piston chamber (2C). Valve opening of the main valves is controlled by an extension-side backpressure chamber (19) and a compression-side backpressure chamber (24). A compression-side check valve (13) and an extension-side check valve (16) are provided at the first piston (3) and the second piston (4). During an extension stroke of the piston rod (10), the compression-side check valve (13) is closed, whereby action of a pressure of a cylinder upper chamber (2A) on the compression-side main valve (23) is prevented.
    Type: Grant
    Filed: March 27, 2008
    Date of Patent: October 1, 2013
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyuki Yamaguchi, Yohei Katayama, Hiroyuki Hayama, Takashi Nezu
  • Publication number: 20120305348
    Abstract: Provided is a suspension apparatus capable of preventing excessive increase in damping force due to a sudden input from the road surface when the damping force is adjusted to a minimum value during running. A damping force control type hydraulic shock absorber (1) includes a damping force adjusting valve (25) which adjusts a damping force by a current supplied to a pressure control valve for controlling a pilot pressure. A control device (ECU) outputs a minimum control current I=0.5 A to cause the damping force control type hydraulic shock absorber (1) to generate a minimum damping force. When the minimum control current is supplied, the pressure control valve of the damping force adjusting valve (25) is always opened. Thus, an increase of the damping force caused by a rapid increase of the pilot pressure due to the sudden input from the road surface is suppressed.
    Type: Application
    Filed: February 12, 2010
    Publication date: December 6, 2012
    Inventors: Yohei Katayama, Takashi Nezu
  • Publication number: 20120247889
    Abstract: During either of the extension and compression strokes, hydraulic liquid flows from a cylinder upper chamber into a reservoir through an annular passage and a damping force control mechanism, and a damping force is generated by the damping force control mechanism. The check valve is provided with a sub-check valve in parallel thereto, which opens in a very low piston speed region to allow the hydraulic liquid to flow through an orifice passage. These check valves are opened successively as the piston speed increases, thereby generating a sufficiently small damping force in the very low piston speed region during the compression stroke of the piston rod, and obtaining a moderate damping force when the piston speed increases.
    Type: Application
    Filed: March 19, 2012
    Publication date: October 4, 2012
    Inventors: Hiroyuki Yabe, Yohei Katayama, Takashi Nezu
  • Publication number: 20120160624
    Abstract: A frequency-dependent mechanism provided at the lower end of a piston rod includes a tubular housing displaceable in an inner tube, together with the piston rod as one unit, and further includes a free piston and O-rings. A shutter of a passage area varying mechanism is provided with an axially extending inner hole, orifices, and oil grooves. The opening area between oil holes 3C and the orifices 33B is changed according to the rotational position of the shutter. The opening area between oil holes 3D and 3E and the oil grooves 33C and 33D and the opening area between oil holes 3F and 3G and the oil grooves 33E and 33F are also variably adjusted according to the rotational position of the shutter.
    Type: Application
    Filed: December 28, 2011
    Publication date: June 28, 2012
    Inventors: Yohei KATAYAMA, Takao Nakadate, Kenji Noda, Mikio Yamashita, Fumiyuki Yamaoka
  • Patent number: 7757826
    Abstract: A first piston and a second piston coupled to a piston rod are fitted in a cylinder, and an intermediate chamber is formed between the first and second pistons. A compression-side check valve and an extension-side check valve are provided at the first piston and the second piston. An extension-side main valve and a compression-side main valve are disposed in the intermediate chamber. A downstream side of a damping force adjusting valve is connected to the intermediate chamber. Inner pressures of an extension-side backpressure chamber and a compression-side backpressure chamber are adjusted by the damping force adjusting valve, whereby valve opening of the extension-side and compression-side main valves is controlled. Hydraulic fluid of the downstream side of the damping force adjusting valve is first sent into the intermediate chamber, and then is sent to a cylinder upper chamber or a cylinder lower chamber.
    Type: Grant
    Filed: March 21, 2008
    Date of Patent: July 20, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyuki Hayama, Yohei Katayama, Takashi Nezu
  • Publication number: 20090272611
    Abstract: A first piston and a second piston coupled to a piston rod are fitted in a cylinder, and an intermediate chamber is formed between the first and second pistons. A compression-side check valve and an extension-side check valve are provided at the first piston and the second piston. An extension-side main valve and a compression-side main valve are disposed in the intermediate chamber. A downstream side of a damping force adjusting valve is connected to the intermediate chamber. Inner pressures of an extension-side backpressure chamber and a compression-side backpressure chamber are adjusted by the damping force adjusting valve, whereby valve opening of the extension-side and compression-side main valves is controlled. Hydraulic fluid of the downstream side of the damping force adjusting valve is first sent into the intermediate chamber, and then is sent to a cylinder upper chamber or a cylinder lower chamber.
    Type: Application
    Filed: March 21, 2008
    Publication date: November 5, 2009
    Inventors: Hiroyuki Hayama, Yohei Katayama, Takashi Nezu
  • Publication number: 20090242339
    Abstract: An object of the present invention is to provide a damping force adjustable hydraulic shock absorber, in which response delay of a pressure control valve and self-excited vibration of a valve body can be prevented. A damping force is generated by controlling an oil flow between an annular oil passage 21 and a reservoir 4 generated by a sliding movement of a piston in a cylinder with use of a back-pressure type main valve 27 and a pressure control valve 28. The damping force is directly generated by the pressure control valve 28, and a valve-opening pressure of the main valve 27 is adjusted by adjusting an inner pressure of a back-pressure chamber 53. In the pressure control valve 28, a valve spring 57 is disposed between a valve body 56 and a plunger 34. A mass of the valve body 56 is sufficiently less than that of a plunger 34, and a spring stiffness of the valve spring 57 is higher than that of a plunger spring 36.
    Type: Application
    Filed: March 31, 2009
    Publication date: October 1, 2009
    Inventors: Takao Nakadate, Takashi Nezu, Yohei Katayama, Shigeo Katayama, Hiroyuki Yabe
  • Publication number: 20080257668
    Abstract: An object of the present invention is to generate a stable damping force and enhance durability of a main valve in a hydraulic shock absorber in which valve opening of the main valve is controlled by an inner pressure of a backpressure chamber. A first piston 3 and a second piston 4 coupled to a piston rod 10 are fitted in a cylinder 2 such that a piston chamber 2C is defined between the first and second pistons 3, 4. An extension-side main valve 18 and a compression-side main valve 23 are provided in the piston chamber 2C. Valve opening of the main valves is controlled by an extension-side backpressure chamber 19 and a compression-side backpressure chamber 24. A compression-side check valve 13 and an extension-side check valve 16 are provided at the first piston 3 and the second piston 4. During an extension stroke of the piston rod 10, the compression-side check valve 13 is closed, whereby action of a pressure of a cylinder upper chamber 2A on the compression-side main valve 23 is prevented.
    Type: Application
    Filed: March 27, 2008
    Publication date: October 23, 2008
    Inventors: Hiroyuki Yamaguchi, Yohei Katayama, Hiroyuki Hayama, Takashi Nezu
  • Patent number: 6981577
    Abstract: In a controllable damping force shock absorber, a piston member connected to a piston rod is disposed in a cylinder in which a magnetic fluid is contained. A disc valve having an extension-stroke pressure-receiving portion and a compression-stroke pressure-receiving portion is provided in the piston member, and a pilot chamber is formed on a rear side of the disc valve. A coil is provided adjacent to passages communicated with the pilot chamber. By energizing the coil, a magnetic field that acts on the magnetic fluid flowing through the passages is generated, changing the viscosity of the magnetic fluid to control a damping force. A valve-opening pressure of the disc valve is controlled according to the pressure in the pilot chamber, such a way that the magnetic fluid exposed to the magnetic field can flow at a low flow rate, thus achieving low power consumption.
    Type: Grant
    Filed: February 26, 2004
    Date of Patent: January 3, 2006
    Assignee: Kabushiki Kaisha Hitachi Seisakusho
    Inventors: Yohei Katayama, Hiroyuki Matsumoto, Kenichi Nakamura, Masaaki Uchiyama
  • Patent number: 6817454
    Abstract: A piston connected to a piston rod is slidably fitted in a cylinder having a hydraulic fluid sealed therein. First and second poppet valves having different valve opening characteristics are provided in first and second extension main passages, respectively. A pilot control valve is provided in a sub-passage. The control pressure of the pilot control valve is adjusted by a proportional solenoid, thereby controlling damping force. At the same time, the pressure at the upstream side of the pilot control valve is introduced into back-pressure chambers to adjust the valve opening pressures of the first and second poppet valves. Because the first and second poppet valves are sequentially opened or closed, damping force can be controlled stepwisely, and ideal damping force characteristics can be obtained.
    Type: Grant
    Filed: December 11, 2002
    Date of Patent: November 16, 2004
    Assignee: Tokico Ltd.
    Inventors: Takashi Nezu, Yohei Katayama
  • Publication number: 20040188200
    Abstract: In a controllable damping force shock absorber, a piston member connected to a piston rod is fittingly disposed in a cylinder in which a magnetic fluid is sealably contained. A disc valve having an extension-stroke pressure-receiving portion and a compression-stroke pressure-receiving portion is provided in the piston member, and a pilot chamber is formed on a rear side of the disc valve. A coil is provided adjacent to passages communicated with the pilot chamber. By energizing the coil for excitation, a magnetic field that acts on the magnetic fluid flowing through the passages is generated, thus changing the viscosity of the magnetic fluid to thereby control a damping force. A valve-opening pressure of the disc valve is controlled according to the pressure in the pilot chamber, in such a way that the magnetic fluid exposed to the magnetic field can be flowed at a low flow rate, thus achieving low power consumption.
    Type: Application
    Filed: February 26, 2004
    Publication date: September 30, 2004
    Inventors: Yohei Katayama, Hiroyuki Matsumoto, Kenichi Nakamura, Masaaki Uchiyama
  • Publication number: 20030106753
    Abstract: A piston connected with a piston rod is slidably fitted in a cylinder having a hydraulic fluid sealed therein. First and second poppet valves having different valve opening characteristics are provided in first and second extension main passages, respectively. A pilot control valve is provided in a sub-passage. The control pressure of the pilot control valve is adjusted by a proportional solenoid, thereby controlling damping force. At the same time, the pressure at the upstream side of the pilot control valve is introduced into back-pressure chambers to adjust the valve opening pressures of the first and second poppet valves. Because the first and second poppet valves are sequentially opened or closed, damping force can be controlled stepwisely, and ideal damping force characteristics can be obtained.
    Type: Application
    Filed: December 11, 2002
    Publication date: June 12, 2003
    Inventors: Takashi Nezu, Yohei Katayama
  • Publication number: 20020121416
    Abstract: A free piston defines a gas chamber in a cylinder, an interior of which is divided into a rod-side chamber and a bottom-side chamber by a piston. An accumulator having a gas chamber is connected to the rod-side chamber by a first oil line, midway of which is provided a damping-force generating unit. Also, the bottom-side chamber and the first oil line are communicated to each other by a communication line, midway of which is provided a spring-constant switchover valve for communication and shut-off of the communication line. Accordingly, when the spring-constant switchover valve puts the communication line in communication, the two gas chambers are compressed to make a spring constant small, thereby making comfort in a vehicle favorable. Meanwhile, the spring-constant switchover valve shuts off the communication line, only one of the gas chambers is compressed to make the spring constant large, thereby limiting a contracting displacement of a piston rod and suppressing rolling of the vehicle.
    Type: Application
    Filed: February 15, 2002
    Publication date: September 5, 2002
    Inventors: Yohei Katayama, Takashi Nezu, Kenichi Nakamura