Suspension system for automotive vehicle or the like

• US 5,358,305 A
• Filed: 06/25/1991
• Issued: 10/25/1994
• Est. Priority Date: 08/13/1987
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Fujishiro, Takeshi, Hanai, Toshimichi, Takahashi, Sadahiro, Kaneko, Takanobu
• Primary Examiner(s): Mitchell, David M.
• Assistant Examiner(s): Pike, Andrew C.
• Application Number:
  US07/718,929
• Time in Patent Office: 1,218 Days
• Field of Search: 296/63, 296/65.1, 296/68.1, 296/, 180/89.13, 180/89.14, 180/282, 280/707, 280/714, 188/299, 188/319, 267/131, 267/175, 267/177, 248/559, 248/566, 248/574, 248/592, 364/424.05
• US Class Current: 296/65.02
• CPC Class Codes: B60G 2600/184 Semi-Active control means
• CPC Class Codes: B60N 2/0224 Non-manual adjustments, e.g. with electrical operation
• CPC Class Codes: B60N 2/502 attached to the base of the seat B60N2/504 takes precedence
• CPC Class Codes: B60N 2/505 Adjustable suspension including height adjustment
• CPC Class Codes: B60N 2/506 Seat guided by rods
• CPC Class Codes: B60N 2/508 Scissors-like structure
• CPC Class Codes: B60N 2/522 characterised by dampening means
• CPC Class Codes: B60N 2/544 Compression or tension springs B60N2/542 takes precedence

Abstract

A seat suspension is provided that has a damper unit which is connected between the seat and the chassis on which the seat is mounted. The damper can be switched between soft and hard settings. The damper switching is controlled based on the relative position of the seat and one of the relative or absolute velocity of the seat. When the seat and the chassis are moving in the same direction the damper is set to soft, (producing a low damping effect), while when the seat and chassis are moving in opposite directions the damper is switched to hard (producing a high damping effect).

Claims

1. In a vehicle provided with a chassis and a seat, a seat suspension system for controllably suspending said seat on said chassis, said seat suspension system comprising:

a spring;

a vibration damper, said vibration damper being self-contained and without an external source of fluid under pressure, said damper including a device for varying damping characteristics of the same;

structural members which operatively interconnect said seat and said chassis, said vibration damper being connected at a first end to said seat and at a second end to said chassis;

a sensor, said sensor being arranged to sense a position of said seat relative to said chassis; and

a control circuit,

said control circuit being arranged to be exclusively responsive to an instantaneous output of said sensor and to control said damper;

wherein said control circuit includes means for determining a position which is indicative of the damper being in a neutral position wherein it is neither compressed or elongated,

means for comparing the instantaneous output of the sensor with respect to the neutral position to determine the relative position of the seat with respect to said chassis,

means for assigning a first polarity to the sensor output if the vibration damper is elongated beyond said neutral position and assigning a second polarity to the output if the vibration damper is compressed beyond said neutral position,

means for determining a relative velocity of the seat from said sensor output,

means for assigning a first polarity to the relative velocity when the seat is moving in a first direction away from said neutral position and a second polarity to the relative velocity when the seat is moving in a second direction away from said neutral position,

means for comparing the polarities of the relative position and the relative velocity of said seat, and

means for conditioning said damper to produce first suspension characteristics when the polarities of the relative position and relative velocity are the same and conditioning said damper to produce second suspension characteristics when the polarities are different.

2. A seat suspension system as claimed in claim 1, further comprising:

tension control means operatively connected to said spring for varying a tension force in said spring, said spring being operatively connected with the structural members of the suspension in a manner such that as the tension force varies then a bias applied to the structural members varies and thus varies a height at which said seat tends to be supported with respect to said chassis.

3. A method of suspending a vehicle seat on a vehicle chassis, comprising the steps of:

interconnecting said seat and said chassis with a damper capable of producing first and second damping characteristics;

sensing a relative position of said seat with respect to said chassis with a sensor exclusively measuring seat displacement;

determining a relative velocity of said seat with respect to said chassis;

assigning a positive sign to said relative position when the relative position is above a predetermined neutral value, and a negative sign when the relative position is below the neutral value;

assigning the positive sign to said relative velocity when said seat is moving in a first direction away from the neutral position and the negative sign when said seat is moving in a second direction away from the neutral position;

controlling said damper to produce only the first damping characteristic when the signs of said relative position and relative velocity are the same; and

controlling said damper to produce only the second damping characteristic when the signs of said relative position and relative velocity are different.

4. In a vehicle, an apparatus comprising:

a chassis;

a seat;

a seat suspension for suspending said seat on said chassis, said seat suspension including a spring and a vibration damper, said damper being self-contained and without an external source of fluid under pressure and including an arrangement for discretely varying damping characteristics of the same, said suspension further including structural members which operatively interconnect said seat and said chassis, said damper being connected between said seat and said chassis and said spring being connected to said structural members;

a first sensor arranged to sense a position of said seat relative to said chassis and to provide a corresponding output;

a second sensor arranged to sense an acceleration of said seat and to provide a corresponding output; and

a control circuit arranged to be exclusively responsive to the outputs of said first and second sensors and to control the damping characteristics of said vibration damper in accordance with a predetermined control schedule;

wherein said control circuit includes;

(1) means for assigning a first polarity to the output of said first sensor if said first sensor indicates that a length of the damper is being elongated beyond a predetermined neutral value and assigning a second polarity to the output of said first sensor if said first sensor indicates that the damper is being compressed beyond said predetermined neutral value;

(2) means for determining a relative velocity of the seat with respect to the chassis from the output of said second sensor;

(3) means for assigning the first polarity to the relative velocity when the seat is moving in a first direction and the second polarity to the relative velocity when the seat is moving in a second direction;

(4) means for comparing the polarities of the relative position and the velocity of said seat; and

(5) means for conditioning said damper to produce first predetermined suspension characteristics when the polarities of said relative position and relative velocity are the same and conditioning said damper to produce second predetermined suspension characteristics when the polarities are different.

5. A seat control system as claimed in claim 4, further comprising:

tension control means operatively connected to said spring for varying a tension in said spring in a manner such as to vary a bias force to thereby vary a height at which said seat tends to be supported above said chassis.

6. A method of suspending a vehicle seaton a vehicle chassis, comprising the steps of:

interconnecting said seat and said chassis with a damper capable of producing first and second damping characteristics;

sensing a position of said seat relative to said chassis;

determining a velocity of said seat relative to said chassis;

assigning a positive sign to said relative position when a relative displacement between the seat and the chassis is increasing beyond a predetermined neutral position, and a negative sign when the relative displacement is decreasing beyond said predetermined neutral position;

assigning the positive sign to said velocity when the seat is moving in a first direction and the negative sign when the seat is moving in a second direction;

controlling said damper to produce only said first damping characteristic when the signs of said relative position and relative velocity are the same; and

controlling said damper to produce only said second damping characteristic when the signs of said relative position and relative velocity are different.

7. In an automotive vehicle, a seating apparatus with controllably adjustable seating, comprising:

a chassis;

a seat having a mass which is small as compared with a mass of said chassis; and

a suspension for suspending said seat on said chassis said suspension comprising

a spring operatively arranged with respect to said suspension so as to apply a base force which controls a height of the seat above said chassis,

a damper including damper control means for discretely varying a damping effect provided by the damper between predetermined high and low levels, said damper being operatively connected between said seat and said chassis,

a displacement sensor operatively disposed for detecting a relative displacement between said seat and said chassis, and

control means, operatively connected between said displacement sensor and said damper control means and exclusively responsive to said displacement sensor, for varying the damping effect of the damper, said control means including means for establishing a neutral seat position as a control parameter, means for deriving the relative displacement between said seat and said chassis, means for assigning a positive polarity to the relative displacement when the seat is moving upwardly from said neutral position and a negative polarity when the seat is moving downwardly from said neutral position, means for deriving a relative velocity between said seat and said chassis from an output of said displacement sensor and means for assigning the positive polarity to the relative velocity when the seat is moving upwardly and the negative polarity when the seat is moving downwardly, and means for outputting a control signal to the damper control means to produce said low damping level when the polarities of said relative displacement and relative velocity are the same and to produce the high damping level when the polarities of said relative displacement and said relative velocity are different.

8. In an automotive vehicle, a seating apparatus with controllably adjustable seating, comprising:

a chassis;

a seat having a means which is small as compared with the mass of said chassis; and

a suspension for suspending said seat on said chassis, said suspension comprising

a spring operatively arranged with respect to said suspension so as to apply a bias force which controls a height of the seat above said chassis,

a damper including damper control means for discretely varying a damping effect provided by the damper between predetermined high and low levels, said damper being operatively connected between said seat and said chassis,

a displacement sensor operatively disposed for detecting a relative displacement between said seat and said chassis, and

control means, operatively connected between said displacement sensor and said damper control means and exclusively responsive to said displacement sensor, for varying the damping effect of the damper, said control means including means for establishing a neutral seat position as a control parameter, means for deriving a relative velocity from an output of said displacement sensor, means subtracting said neutral position from the relative displacement indicated by said displacement sensor, means, when the outcome of the subtraction is positive, for comparing the relative velocity with a predetermined value and setting the damper to said low level if the relative velocity is greater than said predetermined value and setting said damper to said high level if the relative velocity is lower than said predetermined value, and means, when the outcome of the subtraction is negative, for comparing the relative velocity with said predetermined value and setting the damper to said high level if the relative velocity is greater than said predetermined value and setting said damper to said low level if the relative velocity is lower than said predetermined value.

9. In combination, an automotive vehicle comprising:

a chassis;

a seat, said seat having a mass which is small as compared with the mass of said chassis; and

a suspension for suspending said seat on said chassis, said suspension comprising;

a spring, said spring being operatively arranged with said suspension so as to apply a bias which controls the height of the seat above said chassis;

a damper, said damper including control means for discretely varying the damping effect provided by the damper between high and low levels, said damper being operatively connected between said seat and said chassis;

a displacement sensor operatively connected to said seat;

an accelerometer disposed on said seat;

control means operatively connected between said displacement sensor, said accelerometer and said damper control means, said control means including circuitry means for;

deriving a relative velocity between said seat and said chassis from the output of said displacement sensor, assigning a positive polarity to the relative velocity when the seat is moving upward, and assigning a negative polarity when the seat is moving downward;

deriving the absolute velocity of said seat from an output of said accelerometer, assigning a positive polarity to the absolute velocity when the seat is moving upward, and assigning a negative polarity when the seat is moving downward;

outputting a control signal to the damper control means which sets said damper to produce the low damping level when the polarities of the relative velocity and the absolute velocity are the same and outputting a control signal to said damper control means which sets said damper to produce said high damping level when the polarities of the relative velocity and the absolute velocity are different.

10. In combination, an automotive vehicle comprising:

a chassis;

a seat, said seat having a mass which is small as compared with the mass of said chassis; and

a suspension for suspending said seat on said chassis, said suspension comprising;

a spring, said spring being operatively arranged with said suspension so as to apply a bias which controls the height of the seat above said chassis;

a damper, said damper including control means for discretely varying the damping effect provided by the damper between first and second levels, said damper being operatively connected between said and said chassis;

a displacement sensor operatively connected to said seat;

an accelerometer disposed on said seat;

control means operatively connected between said displacement sensor, said accelerometer and said damper control means, said control means including circuitry means for;

deriving the relative velocity between said seat and said chassis from an output of said displacement sensor;

deriving the absolute velocity of said seat from an output of said accelerometer;

comparing, in the event that the absolute velocity is greater than or equal to a first predetermined value, the relative velocity with a second predetermined value, setting the damper to said second level in the event that the relative velocity is less than said second predetermined value, and setting the damper to said first level in the event that the relative velocity is greater than said second predetermined value; and

comparing, in the event that the absolute velocity is less than said first predetermined value, the relative velocity with said second predetermined value and setting said damper to said first level in the event that the relative velocity is lower than said second predetermined value and setting said damper to said second level in the event that the relative velocity is higher than said second predetermined value.

11. A method of suspending a vehicle seat on a vehicle chassis, comprising the steps of:

interconnecting said seat and said chassis with a damper capable of producing first and second damping characteristics;

sensing a relative position of said seat with respect to said chassis;

determining a relative velocity of said seat with respect to said chassis;

assigning a positive sign to said relative position when the relative position is above a predetermined neutral value, and a negative sign when the relative position is below the neutral value;

assigning a positive sign to said relative velocity when said seat is moving in a first direction away from the neutral position and a negative sign when said seat is moving in a second direction away from the neutral position;

controlling said damper to produce the first damping characteristic when the signs of said relative position and relative velocity are the same; and

controlling said damper to produce the second damping characteristic when the signs of said relative position and relative velocity are different,

wherein said damper is controlled to produce the first or second damping characteristic only in response to sensing of said relative position and said relative velocity of said seat with respect to said chassis.