JPH0228143Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is designed to adjust the steering force (response) between high speed (heavy steering force) and stationary steering (light steering force) when the vehicle speed sensor fails. The present invention relates to an electronically controlled power steering device that obtains appropriate steering force at low and high speeds.

In addition to a normal power steering device, the electronically controlled power steering device changes the hydraulic characteristics relative to the steering force depending on the vehicle speed by controlling the hydraulic pressure acting on the reaction plunger installed in the input shaft of the gearbox. This is a device that obtains appropriate steering characteristics according to any vehicle speed and steering condition. In such an electronically controlled power steering device, if the vehicle speed sensor that detects the vehicle speed fails, the vehicle speed is treated as zero, so the steering force becomes lighter at high speeds, resulting in poor running stability.

This idea was made in view of the above points,
The purpose of this is to maintain a moderate steering force at low and high speeds by adjusting the steering force (response) between high speed (heavy steering force) and stationary steering (light steering force) when the vehicle speed sensor fails. An object of the present invention is to provide an electronically controlled power steering device that achieves the following.

Hereinafter, an electronically controlled power steering device according to an embodiment of the invention will be described with reference to the drawings. In the figure, an ignition pulse IGP output from an ignition device (not shown) of the engine is input to a waveform shaping circuit 11 via a diode DI. This waveform shaping circuit 11 outputs a pulse signal corresponding to the ignition pulse IGP, that is, a pulse signal corresponding to the engine rotational speed. Further, the output of the waveform shaping circuit 11 is input to an F/V (frequency/voltage) conversion circuit 12, which outputs a voltage proportional to the frequency of the pulse signal. In other words, the output of the F/V conversion circuit 12 becomes a voltage proportional to the engine speed. Further, the output of the F/V conversion circuit 12 is inputted to a comparison circuit 13, so that the engine rotation speed is a constant rotation speed (for example,
2300rpm) or higher. This constant rotation speed (2300 rpm) is higher than the engine rotation speed when idling when the automatic engine yoke is engaged. In other words, when the car is stopped, the output of the comparison circuit 13 is at L level, and the output of the comparison circuit 13 is at L level.
3 outputs an H level signal when the engine speed is 2300 rpm or higher.

Further, the output of the comparison circuit 13 is input to a timer circuit 14. This timer circuit 14 outputs an H level signal when the output of the comparator circuit 13 continues to be at H level for a certain period of time (for example, 13 seconds). In other words, the timer circuit 14 outputs an H level signal when the engine speed remains at 2300 rpm or more for 13 seconds or more.

Next, 15 is a vehicle speed sensor that detects vehicle speed. This vehicle speed sensor 15 replaces the rotation (vehicle speed) of the output gear of the transmission with a pulse signal. A pulse signal proportional to the vehicle speed output from the vehicle speed sensor 15 is input to a waveform shaping circuit 16. This waveform shaping circuit 16
outputs a pulse signal according to the on/off state of the switch 15S in the vehicle speed sensor 15. The output of this waveform shaping circuit 16 is input to an F/V (frequency/voltage) conversion circuit 17. This F/V conversion circuit 17
outputs a voltage signal proportional to vehicle speed. By the way, when the car is running, this F/V conversion circuit 1
The output of comparator 171 in 7 is H level, L level.
Outputs levels alternately and repeatedly. The output of the comparison circuit 13 is connected to the output of the comparator 171 via the diode D2 in the timer circuit 14. The output of the timer circuit 14 is grounded via a relay coil 18l in the relay 18. Further, the output of the timer circuit 14 is connected to a contact a in a relay 18. In addition, the relay switch 18S of the relay 18 has a contact a when the relay coil 18l is not excited.
Closed on the side. Further, the contact b of the relay 18 is supplied with a voltage that is 1/2 of the power supply voltage Vc. Further, a contact point C within the relay 18 is connected to a solenoid drive circuit 19. Connected to this solenoid drive circuit 19 is a solenoid coil 20 that drives a solenoid valve that controls the pressure acting on a reaction plunger provided in the input shift portion of the gearbox. When the current flowing through the solenoid coil 20 increases, the hydraulic pressure acting on the reaction plunger is controlled to decrease. This solenoid drive circuit 19 has an input voltage (that is, the potential of contact C)
A current flows through the solenoid in inverse proportion to . In other words, when the vehicle speed is high, the output voltage of the F/V conversion circuit 17 becomes large, but the solenoid coil 20
The current flowing through becomes smaller. On the other hand, when the vehicle speed is low, the output voltage of the F/V conversion circuit 17 becomes small, but the current flowing through the solenoid coil 20 becomes large. Here, the potential of the contact b is a potential that maintains the current flowing through the solenoid coil 20 at an intermediate current value between when the vehicle speed is high and when the vehicle speed is low.

Next, the operation of one embodiment of the invention constructed as described above will be explained. A waveform shaping circuit 16 based on the signal output from the vehicle speed sensor 15,
A voltage proportional to the vehicle speed is inputted to the solenoid drive circuit 19 via the F/V conversion circuit 17 via the relay switch 18S. This solenoid drive circuit 1
Reference numeral 9 supplies a current to a solenoid coil 20 in inverse proportion to an input voltage proportional to the vehicle speed. That is, when the vehicle speed is low, the current flowing through the solenoid coil 20 becomes large, and the pressure acting on the reaction force plunger becomes small, so that the steering force becomes light. On the other hand, when the vehicle speed is high, the current flowing through the solenoid coil 20 becomes small, so the steering force becomes heavy.

By the way, the ignition pulse IGP output from the engine's ignition device is generated by a waveform shaping circuit 11,
A voltage proportional to the engine speed is output from the F/V conversion circuit 12 to a comparison circuit 13 via the F/V conversion circuit 12 . Since this comparator circuit 13 outputs an H level signal when the engine speed is 2300 rpm or more, the timer circuit 14 starts a timing operation. Here, when the vehicle speed sensor 15 is not malfunctioning, the output of the comparator 171 repeatedly outputs H level and L level, so when the output of the comparator 171 becomes L level, the timer circuit 14 Since the charge stored in the capacitor C is discharged through the diode D2, the timer circuit 14 stops its timekeeping operation.
In this way, if the vehicle speed sensor 15 is not malfunctioning, the electric charge charged in the capacitor C is discharged via the diode D2 before the timer circuit 14 clocks 13 seconds, so the timer circuit 14 outputs an H level signal. is not output. Therefore, relay switch 1
8S is closed to the contact a side, and as described above, the current flowing through the solenoid coil 20 is controlled by the voltage output from the F/V conversion circuit 17.
That is, as the vehicle speed increases, the current flowing through the solenoid coil 20 decreases, and the hydraulic pressure acting on the reaction plunger increases, so that the steering force becomes heavier. Furthermore, as the vehicle speed decreases, the current flowing through the solenoid coil 20 increases and the steering force becomes lighter.

By the way, if the vehicle speed sensor 15 is out of order due to a disconnection or the like and the output pulse cannot be obtained, the comparator 171 of the F/V conversion circuit 17
The output is always at H level. Therefore, as when the vehicle speed sensor 15 is not malfunctioning, the charge on the capacitor C in the timer circuit 14 is transferred to the diode D2.
is not discharged through. Therefore, when the engine speed remains at 2300 rpm or more for 13 seconds, the timer circuit 14 outputs an H level signal. Therefore,
The relay coil 18l is excited and the relay switch 18S closes to the contact b side. As a result, the solenoid drive circuit 19 receives an intermediate voltage output from the F/V conversion circuit 17 between high speed and low speed. As a result, the current flowing through the solenoid coil 20 is set to an intermediate value between high speed and low speed, and therefore the steering wheel steering force is also set to a value intermediate between low speed and high speed. Therefore, even if the vehicle speed sensor 15 is out of order and the vehicle is driven at high speed, an appropriate steering force can be obtained and driving stability can be maintained. In other words, if the vehicle speed sensor 15 is out of order, it is possible to prevent the vehicle speed from being determined to be zero and the steering force from becoming lighter. Therefore, even if the vehicle speed sensor 15 breaks down while the vehicle is running, the steering force can be maintained at an intermediate level to maintain running stability.

As detailed above, according to this invention, if the vehicle speed sensor fails, the steering force (response) is adjusted between high speed (heavy steering force) and low speed stationary steering (light steering force). Thus, it is possible to provide an electronically controlled power steering device that can generate an appropriate steering force at low and high speeds even if the vehicle speed sensor fails.

[Brief explanation of the drawing]

The drawing is a diagram showing an electronically controlled power steering device according to an embodiment of the invention. 13... Comparison circuit, 14... Timer circuit, 15
...Vehicle speed sensor, 17...F/V conversion circuit, 18
... Relay, 19 ... Solenoid drive circuit, 20
...Solenoid coil.

Claims (1)

[Scope of utility model registration request] In an electronically controlled power steering device having a solenoid valve that controls pressure acting on a reaction plunger provided in an input shaft portion of a gearbox, an engine rotation speed detection means for detecting the rotation speed of an engine, and the engine rotation speed detection means a timer for detecting whether the engine rotational speed continues to be above a certain number of rotations for a certain period of time; a vehicle speed detection means for detecting the vehicle speed; and when a vehicle speed pulse is detected by the vehicle speed detection means, the timer a first voltage generating means for generating a voltage corresponding to the vehicle speed detected by the vehicle speed detecting means; and a first voltage generating means for generating a voltage intermediate between the voltage output from the first voltage generating means. the second voltage generating means, the solenoid coil that drives the solenoid valve, and the second voltage generating means when a certain period of time is measured by the timing means; and means for exciting the solenoid coil by the first voltage generating means.