Pressure control system for suspension

• US 5,024,459 A
• Filed: 12/27/1989
• Issued: 06/18/1991
• Est. Priority Date: 12/28/1988
• Status: Expired due to Term

• Current Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Tagawa, Shinichi, Buma, Shuuichi, Kawanishi, Masaki, Sato, Kunihito, Yonekawa, Takashi, Onuma, Toshio, Ikemoto, Hiroyuki, Hamada, Toshiaki, Suzumura, Nobuyasu, Ohashi, Kaoru, Kokubo, Kouichi, Aburaya, Toshio
• Primary Examiner(s): Rice, Kenneth R.
• Application Number:
  US07/457,957
• Time in Patent Office: 538 Days
• Field of Search: 280/707
• US Class Current: 280/5.501
• CPC Class Codes: B60G 17/016 characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input B60G17/017 takes precedence
• CPC Class Codes: B60G 17/017 characterised by their use when the vehicle is stationary, e.g. during loading, engine start-up or switch-off
• CPC Class Codes: B60G 2202/15 Fluid spring
• CPC Class Codes: B60G 2204/80 Interactive suspensions; arrangement affecting more than one suspension unit
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/106 longitudinal with regard to vehicle, e.g. braking
• CPC Class Codes: B60G 2400/20 Speed
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/30 Propulsion unit conditions
• CPC Class Codes: B60G 2400/38 Speed of engine rotation
• CPC Class Codes: B60G 2400/41 Steering angle
• CPC Class Codes: B60G 2400/50 Pressure
• CPC Class Codes: B60G 2400/51 in suspension unit
• CPC Class Codes: B60G 2400/73 of other part than suspension unit
• CPC Class Codes: B60G 2500/10 Damping action or damper
• CPC Class Codes: B60G 2500/20 Spring action or springs
• CPC Class Codes: B60G 2500/30 Height or ground clearance
• CPC Class Codes: B60G 2600/04 Means for informing, instructing or displaying
• CPC Class Codes: B60G 2600/08 Failure or malfunction detecting means
• CPC Class Codes: B60G 2600/12 : Sampling or average detecting; Addition or substraction
• CPC Class Codes: B60G 2600/14 : Differentiating means, i.e. differential control
• CPC Class Codes: B60G 2600/16 : Integrating means, i.e. integral control
• CPC Class Codes: B60G 2600/20 : Manual control or setting means
• CPC Class Codes: B60G 2600/602 : high pass
• CPC Class Codes: B60G 2600/68 : Filtering means, e.g. fluid filters
• CPC Class Codes: B60G 2600/70 : Computer memory; Data storage, e.g. maps for adaptive control
• CPC Class Codes: B60G 2800/012 : Rolling condition
• CPC Class Codes: B60G 2800/014 : Pitch; Nose dive
• CPC Class Codes: B60G 2800/22 : Braking, stopping
• CPC Class Codes: B60G 2800/244 : Oversteer
• CPC Class Codes: B60G 2800/246 : Understeer

Abstract

A suspension pressure control system applies a pressure which is proportional to a current level supplied to a solenoid of a pressure control valve to a shock absorber associated with a suspension from the valve. When a pressure in a high pressure line which feeds a high pressure to the pressure control valve falls (rises), the pressure applied to the suspension is decreased (increased). Accordingly, the pressure in the high pressure line is detected by a sensor, and if it is low (high), the current level of the pressure control valve is corrected to a high value (low value). In order to prevent an abnormal pressure rise in the suspension which may be caused by an excessive pressure rise in the high pressure line during an idling operation of an engine, a correction which responds to the pressure of the high pressure line is chosen large when a vehicle speed is equal to zero or very low. In order to prevent an abnormality from occurring in the correction of the pressure which is attributable to an errorneous detected value during a failure of operation of sensor, such detected value is determined to be faulty, and in the event a fault occurred, the correction is modified to a given volume (0) which is allocated to a standard pressure in the high pressure line.

Claims

1. Pressure control system for suspension comprising

a pressure source for supplying a fluid which is drawn from a reservoir to a high pressure piping under a high pressure which delivers a hydraulic fluid to a suspension which is adapted to extend and shrink in response to a pressure supplied thereto;

a pressure control valve including a line pressure port communicating with the high pressure piping, a low pressure port communicating with a low pressure, an output port for delivering a pressure to the suspension, a target pressure space communicating with the high pressure piping through an orifice, a spool responsive to a pressure from the output port applied to its one end to be driven in a direction to reduce a degree of communication between the line pressure port and the output port and to increase a degree of communication between the low pressure port and the output port and also responsive to a pressure from the target pressure space applied to its other end to be driven in a direction to increase a degree of communication between the line pressure port and the output port and to reduce a degree of communication between the low pressure port and the output port, a valve element for defining a degree of communication between the target pressure space and the low pressure, and electrical drive means for driving the valve element in a direction to increase/decrease the degree of communication;

pressure detecting means for detecting a pressure in the high pressure piping;

command means for commanding a pressure value to be applied to the suspension;

correction means for correcting the pressure value from the command means in a manner dependent on the pressure detected by the pressure detecting means so as to increase the output value when detected pressure is low;

and electrical energization means for electrically energizing the pressure control valve in accordance with the pressure value as corrected by the correction means so as to deliver a pressure corresponding to the pressure value to the suspension.

2. Pressure control system according to claim 1 in which the correction means derives a compensating value proportional to a deviation of the pressure detected by the pressure detecting means from a predetermined standard value and adds the compensating value to the pressure value from the command means to provide a corrected pressure value.

3. Pressure control system according to claim 2 in which a ratio of the compensating value to the deviation assumes a relatively high, constant value when the pressure detected by the pressure detecting means is equal to or less than a first predetermined value, assumes a relatively small, constant value when the detected pressure is equal to or greater than a second predetermined value which is greater than the first value, and assumes a value between the both constant values which is inversely proportional to the pressure detected by the pressure detecting means when the detected pressure is between the first and the second value.

4. Pressure control system for suspension comprising

an onboard pressure source for supplying a fluid which is drawn from a reservoir to a high pressure piping under a high pressure which delivers a hydraulic fluid to an onboard suspension which is adapted to extend and shrink in response to a pressure supplied thereto;

a pressure control valve including a line pressure port communicating with the high pressure piping, a low pressure port communicating with a low pressure, an output port for delivering a pressure to the suspension, a target pressure space communicating with the high pressure piping through an orifice, a spool responsive to a pressure from the output port applied to its one end to be driven in a direction to reduce a degree of communication between the line pressure port and the output port and to increase a degree of communication between the low pressure port and the output port and also responsive to a pressure from the target pressure space applied to its other end to be driven in a direction to increase a degree of communication between the line pressure port and the output port and to reduce a degree of communication between the low pressure port and the output port, a valve element for defining a degree of communication between the target pressure space and the low pressure, and electrical drive means for driving the valve element in a direction to increase/decrease the degree of communication;

pressure detecting means for detecting a pressure in the high pressure piping;

vehicle speed detecting means for detecting a vehicle speed;

command means for commanding a pressure value to be applied to the suspension;

correction means for correcting the pressure value from the command means in accordance with a pressure detected by the pressure detecting means and a vehicle speed detected by the vehicle speed detecting means so as to increase the pressure value to a higher value when the detected pressure is high and to reduce the pressure value to a low value when the vehicle speed is high;

and electrical energization means for electrically energizing the pressure control valve in accordance with the pressure value as corrected by the correction means so as to apply a pressure corresponding to such pressure value to the suspension.

5. Pressure control system according to claim 4 in which the correction means calculates a first compensating value which inversely corresponds to the pressure detected by the pressure detecting means, and multiplies the first compensating value by a correction value which inversely corresponds to a vehicle speed detected by the vehicle speed detecting means to provide a second compensating value, which is added to the pressure value from the command means to derive a corrected pressure value.

6. Pressure control system according to claim 5 in which the first compensating value assumes a relatively high, constant value when the pressure detected by the pressure detecting means is equal to or less than a third predetermined value, assumes a relatively low, constant value when the detected value is equal to or above a fourth predetermined value which is greater than the third value, and assumes a value between the both constant values which is inversely proportional to the pressure detected by the pressure detecting means when the detected pressure is between the third and the fourth value;

and wherein the correction value which inversely corresponds to the vehicle speed assumes a relatively high, constant value when the vehicle speed detected by the vehicle speed detecting means is equal to or less than a fifth predetermined value, assumes a relatively small, constant value when the detected vehicle speed is equal to or greater than a sixth predetermined value which is greater than the fifth value, and assumes a value between the both constant values which is inversely proportional to the vehicle speed detected by the vehicle speed detecting means when the detected vehicle speed is between the fifth and the sixth value.

7. Pressure control system for suspension comprising

a pressure source for supplying a fluid which is drawn from a reservoir to a high pressure piping under a high pressure which delivers a hydraulic fluid to a suspension which is adapted to extend and shrink in response to a pressure supplied thereto;

a pressure control valve including a line pressure port communicating with the high pressure piping, a low pressure port communicating with a low pressure, an output port for delivering a pressure to the suspension, a target pressure space communicating with the high pressure piping through an orifice, a spool responsive to a pressure from the output port applied to its one end to be driven in a direction to reduce a degree of communication between the line pressure port and the output port and to increase a degree of communication between the low pressure port and the output port and also responsive to a pressure from the target pressure space applied to its other end to be driven in a direction to increase a degree of communication between the line pressure port and the output port and to reduce a degree of communication between the low pressure port and the output port, a valve element for defining a degree of communication between the target pressure space and the low pressure, and electrical drive means for driving the valve element in a direction to increase/decrease the degree of communication;

pressure detecting means for detecting a pressure in the high pressure piping;

command means for commanding a pressure value to be applied to the suspension;

abnormality detecting means for detecting a fault in the detecting operation of the pressure detecting means;

correction means for correcting the pressure value from the command means in accordance with the pressure detected by the pressure detecting means so as to correct the pressure value with a high compensating value when the pressure value is low, and for modifying the compensating value to a given value which is allocated to a predetermined pressure in the high pressure piping whenever the abnormality detecting means has detected a fault in the detecting operation;

and electrical energization means for electrically energizing the pressure control valve in accordance with the pressure value as corrected by the correction means so as to apply a pressure corresponding to such pressure value to the suspension.

8. Pressure control system according to claim 7 in which the correcting means calculates a first compensating value which inversely corresponds to a pressure detected by the pressure detecting means, modifies the first compensating value to a given value which is allocated to a predetermined pressure in the high pressure piping when a fault in the detecting operation is detected by the abnormality detecting means, and adds the first compensating value to the pressure value from the command means to derive a corrected pressure value.

9. Pressure control system according to claim 8 in which the first compensating value which inversely corresponds to the pressure detected by the pressure detecting means assumes a relatively high, constant value when the pressure detected by the pressure detecting means is equal to or less than a third predetermined value, assumes a relatively small, constant value when the detected pressure is equal to or greater than a fourth predetermined value which is greater than the third value, and assumes a value between the both constant values which is inversely proportional to the pressure detected by the pressure detecting means when the detected pressure is between the third and the fourth value.

10. Pressure control system for suspension comprising

an onboard pressure source for supplying a fluid drawn from a reservoir to a high pressure piping under a high pressure which delivers a hydraulic fluid to an onboard suspension which is adapted to extend and shrink in response to a pressure supplied thereto;

a pressure control valve including a line pressure port communicating with the high pressure piping, a low pressure port communicating with a low pressure, an output port for delivering a pressure to the suspension, a target pressure space communicating with the high pressure piping through an orifice, a spool responsive to a pressure from the output port applied to its one end to be driven in a direction to reduce a degree of communication between the line pressure port and the output port and to increase a degree of communication between the low pressure port and the output port and also responsive to a pressure from the target pressure space applied to its other end to be driven in a direction to increase a degree of communication between the line pressure port and the output port and to reduce a degree of communication between the low pressure port and the output port, a valve element for defining a degree of communication between the target pressure space and the low pressure, and electrical drive means for driving the valve element in a direction to increase/decrease the degree of communication;

pressure detecting means for detecting a pressure in the high pressure piping;

vehicle speed detecting means for detecting a vehicle speed;

command means for commanding a pressure value to be applied to the suspension;

abnormality detecting means for detecting a fault in the detecting operation of the pressure detecting means;

correction means for correcting the pressure value from the command means in accordance with a pressure detected by the pressure detecting means and a vehicle speed detected by the vehicle speed detecting means by using a compensating value which assumes a high value when the detected pressure is high and which assumes a low value when the detected pressure is high, and for modifying the compensating value to a given value which is allocated to a predetermined pressure in the high pressure piping whenever a fault in the detecting operation is detected by the abnormality detecting means;

and electrical energization means for electrically energizing the pressure control valve in accordance with the pressure value as corrected by the correction means so as to apply a pressure corresponding to such pressure value to the suspension.

11. Pressure control system according to claim 10 in which the correction means calculates a first compensating value which inversely corresponds to a pressure detected by the pressure detecting means, multiplies the first compensating value by a correction value which inversely corresponds to a vehicle speed detected by the vehicle speed detecting means to provide a second compensating value, modifies the second compensating value to a given value which is allocated to a predetermined pressure in the high pressure piping when a fault in the detecting operation is detected by the abnormality detecting means, and adds the second compensating value to the pressure value from the command means to derive a corrected pressure value.

12. Pressure control system according to claim 11 in which the first compensating value assumes a relatively high, constant value when a pressure detected by the pressure detecting means is equal to or less than a third predetermined value, assumes a relatively small, constant value when the detected pressure is equal to or greater than a fourth predetermined value which is greater than the third value, and assumes a value between the both constant values which is inversely proportional to a pressure detected by the pressure detecting means when the detected pressure is between the third and the fourth value;

and wherein the compensating value which inversely corresponds to the vehicle speed assumes a relatively high, constant value when a vehicle speed detected by the vehicle speed detecting means is equal to or less than a fifth predetermined value, assumes a relatively small, constant value when the detected vehicle speed is equal to or greater than a sixth predetermined value which is greater than the fifth value, and assumes a value between the both constant values which is inversely proportional to the vehicle speed detected by the vehicle speed detecting means when such vehicle speed is between the fifth and the sixth value.