Electrical shock absorber

• US 8,596,430 B2
• Filed: 06/17/2010
• Issued: 12/03/2013
• Est. Priority Date: 06/17/2010
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Ogawa, Atsushi
• Primary Examiner(s): SCHWARTZ, CHRISTOPHER P
• Application Number:
  US13/321,094
• Publication Number:
  US 20120186920A1
• Time in Patent Office: 1,265 Days
• Field of Search: 188/267, 188/267.1, 188/267.2, 280/124.108, 280/5.51
• US Class Current: 188/267
• CPC Class Codes: B60G 17/015 the regulating means comprising electric or electronic elements B60G17/002, B60G17/005 take precedence
• CPC Class Codes: B60G 17/06 Characteristics of dampers , e.g. mechanical dampersB60G17/015 takes precedence
• CPC Class Codes: B60G 2300/60 Vehicles using regenerative power
• CPC Class Codes: F16F 15/03 using magnetic or electromagnetic means F16F9/53, F16F15/005 take precedence
• CPC Class Codes: F16F 15/035 by use of eddy or induced-current damping dynamo-electric brakes of the eddy-current type H02K49/04
• CPC Class Codes: F16F 2232/06 Translation-to-rotary conversion
• CPC Class Codes: H02P 3/12 by short-circuit or resistive braking

Abstract

An electrical shock absorber 20 of the present embodiment includes a motor 21, which is rotated by approaching and separating motions between sprung and unsprung members which approach and separate from each other; and an electric circuit 50, which connects the electric terminals of the motor 21 so as to cause current to flow through the motor 21. The electric circuit 50 includes P-channel JFETs 56, 60. The gate of the P-channel JFET 56, 60 is connected to one electric terminal of the motor 21, and the source of the P-channel JFET 56, 60 is connected to the other electric terminal of the motor 21. Therefore, the induced voltage is applied to the gate. The induced voltage represents the stroke speed of the electrical shock absorber 20. Therefore, the gate voltage VGS is changed on the basis of the above-mentioned relative speed such that the gate voltage VGS increases with the stroke speed of the electrical shock absorber 20. By means of changing the gate voltage VGS in this manner, the magnitude of the induced current flowing through the electric circuit 50 is limited by the P-channel JFETs 56, 60 on the basis of the characteristic of the P-channel JFET 56, 60 in terms of change of drain-source current iDS with the gate voltage VGS.

Claims

1. An electrical shock absorber comprising:

a motor which is rotated by approaching and separating motions between first and second members which approach and separate from each other; and

an electric circuit which connects two electric terminals provided on the motor so as to cause current to flow through the motor,

the electrical shock absorber being configured such that, when the motor is rotated by an approaching motion or separating motion between the first and second members, an induced voltage appears between the two electric terminals, and an induced current flows through the motor and the electric circuit, whereby the electrical shock absorber generates a damping force against the approaching motion or separating motion between the first and second members,

a P-channel junction field effect transistor provided in the electric circuit;

the P-channel junction field effect transistor connected to the electric circuit such that the induced current flowing through the electric circuit can flow through a drain-source path of the P-channel junction field effect transistor, wherein

the P-channel junction field effect transistor limits the magnitude of the induced current flowing through the electric circuit by using an electrical characteristic of the P-channel junction field effect transistor in terms of change of a drain-source current iDS with a gate voltage VGS which is applied to the P-channel junction field effect transistor and is changed on the basis of relative speed between the first member and the second member such that the magnitude of a drain-source current iDs decreases as the gate voltage VGS of the P-channel junction field effect transistor increases.

2. An electrical shock absorber according to claim 1, wherein the gate voltage VGS is changed on the basis of the magnitude of the induced voltage.

3. An electrical shock absorber according to claim 2, wherein the gate of the field effect transistor is connected to the electric circuit such that the gate voltage VGS changes on the basis of the magnitude of the induced voltage.

4. An electrical shock absorber according to claim 1, wherein the electric circuit includes a first connection path in which the P-channel junction field effect transistor is provided, and a second connection path in which a resistor element is provided and which is connected in parallel to the first connection path.

5. An electrical shock absorber according to claim 4, wherein

a resistor element is provided in the first connection path;

and

the P-channel junction field effect transistor limits the magnitude of current flowing through the first connection path on the basis of the characteristic of the P-channel junction field effect transistor in terms of change of the drain-source current iDS with the gate voltage VGS.

6. An electrical shock absorber according to claim 1, wherein

the electric circuit includes a first electric circuit through which a current flows when the motor rotates in one direction as a result of an approaching motion between the first member and the second member, and a second electric circuit through which a current flows when the motor rotates in the other direction as a result of a separating motion between the first member and the second member;

and

the P-channel junction field effect transistor is provided in each of the first electric circuit and the second electric circuit.

7. An electrical shock absorber according to claim 6, wherein

the first electric circuit includes a first connection path in which the P-channel junction field effect transistor is provided and a second connection path in which a resistor element is provided and which is connected in parallel to the first connection path;

and

the second electric circuit includes a first connection path in which the P-channel junction field effect transistor is provided and a second connection path in which a resistor element is provided and which is connected in parallel to the first connection path of the second electric circuit.

8. An electrical shock absorber according to claim 7, wherein

a resistor element is provided in each of the first connection path of the first electric circuit and the first connection path of the second electric circuit;

the P-channel junction field effect transistor provided in the first connection path of the first electric circuit limits the magnitude of the current flowing through the first connection path of the first connection circuit on the basis of the characteristic of the P-channel junction field effect transistor provided in the first connection path of the first electric circuit in terms of change of the drain-source current iDS with the gate voltage VGS; and

the P-channel junction field effect transistor provided in the first connection path of the second electric circuit limits the magnitude of the current flowing through the first connection path of the second electric circuit on the basis of the characteristic of the P-channel junction field effect transistor provided in the first connection path of the second electric circuit in terms of change of the drain-source current iDS with the gate voltage VGS.