Solenoid driving circuit for automatic transmission

• US 5,251,091 A
• Filed: 06/18/1991
• Issued: 10/05/1993
• Est. Priority Date: 06/18/1990
• Status: Expired due to Term

• Current Assignee: Aisin AW Company Limited (Aisin Corp.)
• Original Assignee: Aisin AW Company Limited (Aisin Corp.)
• Inventors: Yamada, Kunihiro, Ito, Yasunobu
• Primary Examiner(s): Gaffin, Jeffrey A.
• Application Number:
  US07/717,193
• Time in Patent Office: 840 Days
• Field of Search: 361/152.4, 361/160, 361/194, 361/205, 361/42, 361/45, 361/49, 307/9.1, 307/10.1, 251/129.05, 123/490
• US Class Current: 361/152
• CPC Class Codes: F16H 2061/0258 Proportional solenoid valve
• CPC Class Codes: F16H 2061/1208 with diagnostic check cycles; Monitoring of failures
• CPC Class Codes: F16H 2061/1232 Bringing the control into a predefined state, e.g. giving priority to particular actuators or gear ratios
• CPC Class Codes: F16H 2061/1268 Electric parts of the controller, e.g. a defect solenoid, wiring or microprocessor
• CPC Class Codes: F16H 59/24 dependent on the throttle opening
• CPC Class Codes: F16H 61/0251 Elements specially adapted for electric control units, e.g. valves for converting electrical signals to fluid signals
• CPC Class Codes: F16H 61/12 Detecting malfunction or potential malfunction, e.g. fail safe in control of hydrostatic gearing F16H61/4192; Circumventing or fixing failures
• CPC Class Codes: F16H 61/686 with orbital gears
• CPC Class Codes: G01R 31/007 using microprocessors or computers

Abstract

A solenoid driving circuit for an automatic transmission in which a potential difference compensating device, such as a Darlington-connected transistor circuit, switching transistor, and/or diode, is connected between a resistance element and a power ground, and a controlling device monitors voltage values at opposite sides of the resistor element so as to detect a current value flowing across a solenoid. The controlling device determines whether the detected value of the current flowing across the solenoid is abnormal, and the controlling device shuts off the current of a solenoid driving device when it is abnormal. The potential difference compensating device is provided with a switching device, and the controlling device turns off the switching device when the monitoring current value is abnormal. This circuit prevents an excessive current from flowing to the solenoid and an excessive discharge from the potential difference compensating device to the power ground owing to a short circuit with the supply line of a battery.

Claims

1. A solenoid driving circuit for an automatic transmission for a vehicle, comprising:

a solenoid disposed in a hydraulic controller of the automatic transmission for a vehicle, said hydraulic controller controlling hydraulic pressure supplied thereto;

solenoid driving means for driving said solenoid with an actuating current;

setting means for setting a value for said actuating current;

a resistance element electrically connected in series with said solenoid;

a Darlington-connected transistor circuit electrically connected between the resistance element and a power ground;

first detecting means for detecting a voltage of a connecting point between the solenoid and the resistance element, said first detecting means being connected to a signal ground;

second detecting means for detecting a voltage of a connecting point between the resistance element and the Darlington-connected transistor circuit, said second detecting means being connected to the signal ground;

monitoring current determining means for receiving the detected voltages of the first and second detecting means and for calculating a monitoring current as a function of a voltage difference between opposite ends of the resistance element;

controlling means for effecting feedback control of the actuating current by comparing the calculated monitoring current with the set value and generating an error signal on the basis of said comparing, said actuating current being corrected to said set value responsive to said error signal, said controlling mens being connected to a signal ground; and

wherein said controlling means includes abnormality determining means for determining if the calculated monitoring current is abnormal and for turning off said Darlington-connected transistor circuit when the monitoring current value is determined to be abnormal.

2. The solenoid driving circuit of claim 1 further comprising a pulse width modulated signal outputting means for receiving a basic pulse width signal from said setting means and said error signal and for outputting a pulse width modulated signal at a constant, predetermined frequency to said solenoid driving means.

3. A solenoid driving circuit for an automatic transmission for a vehicle, comprising:

a solenoid disposed in a hydraulic controller of the automatic transmission for a vehicle, said hydraulic controller controlling hydraulic pressure supplied thereto;

solenoid driving means for driving said solenoid with an actuating current;

setting means for setting a value for said actuating current;

a resistance element electrically connected in series with said solenoid;

a switching transistor in series with a diode electrically connected between the resistance element and a power ground;

first detecting means for detecting a voltage of a connecting point between the solenoid and the resistance element, said first detecting means being connected to a signal ground;

second detecting means for detecting a voltage of a connecting point between the resistance element and the switching transistor, said second detecting means being connected to the signal ground;

monitoring current determining means for receiving the detected voltages of the first and second detecting means and for calculating a monitoring current as a function of a voltage difference between opposite ends of the resistance element;

controlling means for effecting feedback control of the actuating current by comparing the calculated monitoring current with the set value and generating an error signal on the basis of said comparing, said actuating current being corrected to said set value responsive to said error signal, said controlling means being connected to a signal ground; and

wherein said controlling means includes abnormality determining means for determining if the calculated monitoring current is abnormal and for turning off said switching transistor when the monitoring current value is determined to be abnormal.

4. The solenoid driving circuit of claim 3 further comprising a pulse width modulated signal outputting means for receiving a basic pulse width signal from said setting means and said error signal and for outputting a pulse width modulated signal at a constant, predetermined frequency to said solenoid driving means.