JPH037546B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a power system that variably controls steering force in response to vehicle speed using a control characteristic selected from a plurality of steering force control characteristics by a switch operation. This invention relates to a steering device.

(Prior art) Conventionally, in a power steering device that variably controls the steering force in response to the vehicle speed through electronic control by a microcomputer, as shown in Fig. 1, for example, H ，
Three types of steering force control characteristics, N and L, are defined, and the driver can select one of the control characteristics by operating a switch according to his/her judgment, and the steering force can be controlled in response to vehicle speed according to the selected control characteristic. I have to.

However, with such conventional power steering devices equipped with a control characteristic selection function, it is expected that the switch for selecting the control characteristics will break down after long periods of use, and switch failure is likely to occur. If this occurs, the switch signal may not be obtained at all even if the switch is selectively operated, or two or more switch signals may be obtained, and in either case, one of the H, N, and L control characteristics may not be obtained. The operator does not know which one to select, and is forced to make a decision based on the steering feel.

Also, considering the loss of the selection function due to a switch failure, if the difference in steering force between the H, N, and L control characteristics is increased, the steering sensation will be distorted when the wrong control characteristic is selected due to a switch failure. As a result, even if three types of control characteristics are provided, the difference in steering force due to switching of control characteristics cannot be increased. There was a problem of not being able to produce enough.

(Object of the Invention) The present invention has been made in view of such conventional problems, and provides a vehicle speed-sensitive power steering device having at least three types of steering force control characteristics selected by switch operation. To provide a power steering device which minimizes changes in steering sensation by appropriately selecting steering force control characteristics in the event of a switch failure, and can sufficiently compensate for differences in steering force for each control characteristic. purpose.

(Structure of the Invention) In order to achieve this object, the present invention has at least three types of steering force characteristics that differ in steering force with respect to vehicle speed, and selects the steering force control characteristic by operating a selection switch. In a power steering device that variably controls steering force in response to vehicle speed according to control characteristics, when a switch failure of the selection switch is detected, control provides an intermediate steering force for vehicle speed among a plurality of control characteristics. This allows you to select characteristics.

(Embodiment) FIG. 2 is a circuit block diagram showing an embodiment of the present invention.

First, to explain the configuration, 1 is a control unit, which has a built-in controller 2 using a microcomputer, and the output of a vehicle speed sensor 3 that detects the vehicle speed is connected to the controller 2 as an input, and the controller 2 is set to the controller 2. A selection switch circuit 4 for selecting any one of the three types of steering characteristics H, N, and L is connected as an input.

The selection switch circuit 4 has a changeover switch 5 with changeover contacts H, N, and L, and a resistor R is connected to each changeover terminal.
1 and parallel connected diodes D1, D2, D
Battery voltage +Vb is applied through 3, and when the changeover switch 5 is in the connected position, the switch signal for the controller 2 is pulled to the L level, and when the changeover switch 5 is in the open position, the battery voltage +Vb is applied and an H level output is generated. There is.

The control output of the steering force in response to the vehicle speed by the controller 2 is given to the base of the power transistor 6, the collector of the power transistor 6 is connected to an actuator 7 for variable control of the steering force, and the emitter of the power transistor 6 is connected to an actuator 7 for variable control of the steering force. is connected to a current detection resistor 8 that detects the drive current of the actuator 7, and feeds back a detection voltage corresponding to the drive current of the current detection resistor 8 to the controller 2, and causes the actuator 7 to flow due to the conduction of the transistor 6 due to the control output of the controller 2. The drive current can be controlled at constant current.

Further, power is supplied to the control unit 1 and the actuator 7 by turning on the ignition switch 9, and the output from the ignition switch 9 is supplied to the power fuses 10 and 11 provided separately.
Power is supplied through two systems via the .

FIG. 3 is a circuit block diagram showing the specific circuit configuration of the controller 2 in the embodiment of FIG. 2 together with the selection switch circuit 4. Three signal lines from the selection switch circuit 4 are input to the pattern selection circuit 12. The pattern selection circuit 12 outputs a selection signal of a steering force control characteristic based on a switch signal that becomes L level among the switch signals generated by operating the changeover switch 5 of the selection switch circuit 4. The output of the pattern selection circuit 12 is given to a memory circuit 13, and the memory circuit 13 stores in advance three types of steering force control characteristics, H, N, and L shown in the graph of FIG. Control characteristics corresponding to H, N, and L selection signals from the selection circuit 12 are read out. The output of the memory circuit 13 is given to the vehicle speed sensitive control circuit 14, and the vehicle speed sensitive control circuit 14 receives the detected vehicle speed input from the vehicle speed sensor 3 according to the control characteristics read out from the memory circuit 13 by selection by the selection switch circuit 4. It calculates the steering force and outputs a control signal for controlling the current of the power transistor 6 shown in FIG.

On the other hand, the three signal lines from the selection switch circuit 4 are also input connected to the failure detection circuit 15, and the failure detection circuit 15 selects when only one of the three switch signals is at L level. It is assumed that the switch circuit 4 is normal, and when all three switch signals go to H level or two or more switch signals go to L level, it is determined that the selection switch circuit 4 is malfunctioning, and the storage circuit 13 In contrast, a selection signal is output for a control characteristic N that provides an intermediate steering force with respect to the vehicle speed among the three control characteristics H, N, and L shown in FIG. Furthermore, the failure detection circuit 15 detects the pattern selection circuit 1 when a failure is detected.
2, and outputs a prohibition signal to pattern selection circuit 1.
2 is prohibited from selecting the control characteristics.

Next, the operation of the above embodiment will be explained with reference to the flowchart of FIG.

The operation of the power steering device is performed by supplying battery power by turning on the ignition switch 9, and after completing the predetermined initial processing, the fifth
Execute the flow shown in the figure.

At this time, if the changeover switch 5 of the selection switch circuit 4 has selected the changeover terminal H, that is, the control characteristic H, as shown in FIGS. At this time, the switch signal of the switching terminal N is H.
Since it is at the level, the process advances to the next judgment block b, and the switch signal from the switching terminal H is checked. At this time, since the changeover switch 5 has been switched to the changeover terminal H, the switch signal in determination block b is at L level, and since the switch signal due to the selection of control characteristic H has been obtained, the process proceeds to block f. , sets the H flag for selecting the control characteristic H, and in the next judgment block c, judges the switch signal from the switching terminal L of the selection switch circuit 4, and at this time, the switch signal from the switching terminal L goes to H level. Discrimination block d based on certain things
Then, the number n of flags is compared and determined.

In this normal process, only the H flag is obtained in block f, so the number of flags n=1, and the process proceeds to block h, where the control characteristic corresponding to flag H, that is, the control characteristic selected by selection switch circuit 4, is determined. According to H, variable control of the steering force is performed in response to vehicle speed.

Furthermore, even if another control characteristic N or L is selected by the selection switch circuit 4, if N is selected, the N flag will be obtained in block e, and if control characteristic L is selected, the L flag will be obtained in block g. In this case as well, since the number of flags n is 1, variable control of the steering force in response to the vehicle speed is performed in block h by selecting a control characteristic according to the flag N or L.

Next, if a switch failure occurs in the selection switch circuit 4, all the switch signals will become H level, or two or more switch signals will become L level. In the event of a failure in the selection switch circuit 4, the determination blocks a to c
When the number of flags n obtained in the process leading to is greater than n=0 or n=2, it is determined that the selection switch is malfunctioning. In this way, when a switch failure is determined, block i uniquely selects control characteristic N, which is an intermediate characteristic between control characteristics H and L, and switches to variable control of steering force that is sensitive to vehicle speed. Well,
Further, the process proceeds to block j, in which a failure of the selection switch is alerted to the driver by lighting up an alarm lamp provided on the instrument panel or the like.

The processing shown in the flowchart of FIG. 5 can be realized not only by the circuit block of FIG. 3 but also by program control of a microcomputer.

Note that the above embodiment takes as an example the case where three types of control characteristics with different steering forces are used for the vehicle speed, but the same method can be applied to other embodiments in which three or more types of control characteristics are used. The present invention can be applied to three or more types of control characteristics, and when a failure of the selection switch is detected, it is sufficient to fixedly select a control characteristic located in the middle among a plurality of control characteristics having different steering forces with respect to vehicle speed.

(Effects of the Invention) As described above, according to the present invention, there are at least three types of steering force control characteristics in which the steering force differs with respect to the vehicle speed, and a selection switch is provided to select one of the plurality of steering force control characteristics. In a power steering device that variably controls the steering force in response to the vehicle speed according to the selected control characteristic, when a failure of the selection switch is detected, the intermediate Since the control characteristic that provides the steering force is selected, the steering characteristic that provides the largest steering force or the smallest steering force relative to the vehicle speed is switched to an intermediate control characteristic upon detection of a failure in the selection switch. Changes in force are minimized, and changes in steering feel due to fail-safe operation in the event of a failure of the selection switch can be suppressed to ensure safe steering operation. In addition, when a failure is detected in the selection switch, the control characteristic is switched to a control characteristic with an intermediate steering force to minimize changes in steering force, so the difference in steering force for each control characteristic can be made sufficiently large. It is possible to appropriately change the steering feel by switching the characteristics.

[Brief explanation of the drawing]

Fig. 1 is a graph diagram showing conventional steering force control characteristics, Fig. 2 is a circuit block diagram showing an embodiment of the present invention, and Fig. 3 is a block diagram showing an embodiment of the controller in Fig. 2. 4 is a graph showing control characteristics of steering force used in an embodiment of the present invention, and FIG. 5 is a flowchart showing control processing according to an embodiment of the present invention. 1: Control unit, 2: Controller, 3: Vehicle speed sensor, 4: Selection switch circuit, 5: Changeover switch, 6: Power transistor, 7: Actuator, 8: Current detection resistor, 9: Ignition switch, 10, 11: Power switch, 12: Pattern selection circuit, 13: Memory circuit, 14: Vehicle speed sensitive control circuit, 15: Failure detection circuit.

Claims (1)

[Scope of Claims] 1. A storage means storing at least three types of steering force control characteristics having different steering forces with respect to vehicle speed, a selection switch for selecting the control characteristics stored in the storage means, and a selection switch for selecting the control characteristics stored in the storage means; A power steering device comprising a vehicle speed sensitive control means for variable control of steering force in response to vehicle speed according to control characteristics, wherein when a failure of the selection switch is detected, the plurality of steering forces stored in the storage means are A power steering device comprising: a failure selection means for selecting a steering force control characteristic that provides an intermediate steering force with respect to a vehicle speed among the control characteristics and setting the selected steering force control characteristic to the front vehicle speed sensing means.