JPH0419064B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applied to a power steering device that adjusts an assist force for steering operation in response to an electric signal, and generates a vehicle speed signal according to the traveling speed of the vehicle. and a steering angle signal generating means that generates a steering angle signal corresponding to the steering angle. The present invention relates to a control device for a power steering device.

[Conventional technology]

This type of control device for a power steering device is known, for example, from Japanese Patent Laid-Open No. 57-209471. According to this control device, when the steering angle is larger than the set angle, as the vehicle speed increases and as the steering angle increases, the assisting force for the occupant's steering operation is gradually reduced, and the occupant's operating force is accordingly reduced. Gradually make it heavier.

[Problem to be solved by the invention]

In the conventional device described above, the steering assist force is determined by the steering angle in any steering state as long as the vehicle is traveling at the same speed. Therefore, for example, when a passenger operates the steering wheel in a direction approaching the neutral position while the vehicle is traveling at the same speed, the operating force is heavy at the beginning of the steering operation, making it difficult to quickly return the steering wheel to the neutral position, which may affect the running stability of the vehicle. may be damaged.

The present invention has been made in view of the above problems, and an object thereof is to provide a control device for a power steering device that can control steering assist force without impairing the running stability of a vehicle. do.

[Means for Solving the Problems] In order to achieve the above object, a control device for a power steering device of the present invention is adapted to a power steering device that adjusts an auxiliary force for a steering operation in response to an electric signal, and The vehicle speed signal and the steering angle signal are received from a vehicle speed signal generating means that generates a vehicle speed signal corresponding to the traveling speed of the vehicle, and a steering angle signal generating means that generates a steering angle signal corresponding to the steering angle, and the vehicle speed and the steering angle are determined. In a control device for a power steering device that reduces the auxiliary force as the angle increases, the steering operation determines whether the direction of the steering operation is toward a neutral position of the steering wheel or a direction away from the neutral position of the steering wheel. direction determining means; and based on the results of the steering operation direction determining means,
When the same vehicle speed signal is generated by the vehicle speed signal generating means, adjusting means increases the auxiliary force when the steering direction is approaching the neutral position than when the steering direction is moving away from the neutral position. Its gist is to provide the following.

[Effect]

With the above configuration, while traveling at the same speed, the steering assist force decreases as the steering angle increases if the steering direction is away from the neutral position, and decreases as the steering angle approaches the neutral position. By means of the adjusting means, it is increased more than in the direction away from the neutral position. In other words, while traveling at the same speed,
When the steering wheel is operated in a direction away from the neutral position, the assisting force decreases as the steering angle increases, making the steering operation heavier.
Conversely, when the steering wheel is steered in a direction approaching the neutral position, the auxiliary force becomes larger than before, the steering operation becomes lighter, and the steering wheel can be quickly returned to the neutral position.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of this embodiment.

In FIG. 1, a vehicle speed signal generating means 1 is installed on the output shaft of a transmission 10, and generates a pulse signal having a frequency proportional to the vehicle speed using an electromagnetic pickup method or the like, and inputs it to a control circuit 2.
Alternatively, it is configured to be attached to the analog speedometer 11 and input a pulse signal similar to that described above to the control circuit 2.

The steering signal generating means 4 is connected to the steering shaft 1
2, and has a configuration as shown in FIG. 6, and is configured to input to the control circuit 2 an analog voltage signal having a level value corresponding to the steering operation position, that is, the steering operation position.

The auxiliary force adjusting means 3 includes an oil tank 13, an oil pump 15 which is rotationally driven by an engine 14 and whose discharge amount is adjusted by a drive signal from the control circuit 2, and an auxiliary force proportional to the discharge amount from the oil pump 15. occurs, steering wheel 1
The main component is a power cylinder 18 that applies an auxiliary force to the power transmission mechanism that finally changes the front wheels 17, 17 into a swinging motion by the rotational operation force of the power cylinder 18.

To conceptually explain this auxiliary force adjustment means 3,
As shown in FIG. 2, the oil in the oil tank 13 is converted into high-pressure oil by the vane pump 19 in the oil pump 15, and a flow rate control valve 20 is provided in the passage between the discharge side of the vane pump 19 and the inflow side of the power cylinder 18. The oil flow rate supplied to the power cylinder 18 is adjusted by adjusting the auxiliary force. Here, the flow rate control valve 20 includes a solenoid coil 21 through which a drive current from the control circuit 2 flows, and an electromagnetic plunger 22. As the amount of current flowing through the solenoid coil 21 increases, the amount of displacement of the electromagnetic plunger 22 increases. The oil flow rate is reduced. Incidentally, reference numeral 23 is a flow control valve for keeping the pressure of high-pressure oil supplied to the power cylinder 18 constant.

FIG. 3 shows an electrical block diagram of this embodiment.

In FIG. 3, the control circuit 2 has a configuration including a microcomputer, and mainly uses the vehicle speed detection means 1.
The waveform shaping circuit 24 that shapes the waveform of a pulse signal having a frequency proportional to the vehicle speed from the waveform shaping circuit 2
The interrupt command signal is sent to the microprocessor unit (MPU) based on the shaped pulse signal from 4.
25, and an A/D converter 28 that converts the analog voltage signal from the steering operation detection means 4 into a digital signal and sends it to the data bus on the common bus 27. A read-only memory (ROM) 29 in which control programs necessary for data processing are stored in advance, and a random access memory (RAM) 30 in which data necessary for data processing are temporarily written and read are An MPU 2 that executes data processing according to the control program, finally calculates auxiliary amount data corresponding to the auxiliary force, and sets a count value corresponding to the duty ratio of the pulse signal corresponding to the data to a down count 31.
5 amplifies the power of the pulse signal from the down count 31 and the common bus 27 consisting of a data bus, an address bus, and a control bus, and energizes the solenoid coil 21 of the auxiliary force adjustment means 3 with the amplified pulse signal, that is, the drive signal. Power amplifier circuit 32
It is equipped with Note that reference numerals 33 and 34 in the figure represent a key switch and an on-vehicle battery, respectively.

Next, while referring to the flowchart in Figure 4,
Processing by the MPU 25 will be explained.

When the key switch 33 is turned on and the engine is started, step 100 is first executed to perform initial settings for subsequent processing.

Next, step 101 is executed to calculate vehicle speed data V _B and write the vehicle speed data V _B to a predetermined address in RAM 30 . In performing this vehicle speed calculation process, the vehicle speed data V B is actually calculated by executing an interrupt routine (not shown) that starts interrupt processing every time an interrupt command signal is sent from the interrupt control unit ₂₆ . Although it is created, it is well known so its explanation will be avoided.

Next, step 102 is executed, the vehicle speed data V _B is read from the RAM 30, the reference steering operation speed V _SO is calculated from the function f (V _B ) having the vehicle speed V _B as a parameter, and the reference steering operation speed data V _SO is transferred to the RAM 30.
Write to the predetermined address of 0. Here, the reference steering operation speed V _SO is calculated by V _SO =-K ₀ V _B + K ₁ (both K ₀ and K ₁ are positive constants), as shown by the line L1 in FIG. 5, for example.

Next, step 103 is executed to take in the digital signal corresponding to the current steering operation position P via the A/D converter 28, that is, the current steering operation position data P, and also to take in the digital signal corresponding to the current steering operation position P through the A/D converter 28. The previous steering operation position data P' written in a predetermined address is read out from the RAM 30, and the above steering operation position data P,
From P' and the time t required from the previous execution of step 103 to the current execution of step 103, (P-P')/
t, that is, the steering operation speed V _S is calculated, and the steering operation speed data V _S and steering operation position data P, P' are respectively written to predetermined addresses in the RAM 30.

Next, step 104 is executed, the steering operation speed data V _S is read from the RAM 30, and the steering operation speed data is read out from the RAM 30.
Whether V _S is "0" or more, that is, the direction of the steering operation is to the right (including when traveling straight) as is clear from the potentiometer-type steering operation detection means 4 shown in FIG. After the judgment, the steering operation speed data V _S is stored in the RAM.
30 predetermined addresses.

If it is determined that the steering operation direction is right, then step 105 is executed to obtain the steering operation position data P.
Steering neutral position (reference value) data read from the RAM 30 and stored in advance in the ROM 29 corresponding to the steering neutral position, that is, P _C in FIG.
Read P _C and compare the above steering operation position P with the reference value P _C to determine whether the steering operation position P is larger than the reference value P _C , that is, whether the front wheels are facing to the right with respect to the straight-ahead direction. At the same time, after the determination, the steering operation position data P is written to a predetermined address in the RAM 30.

If it is determined that the front wheels are facing to the left, then step 106 is executed and the vehicle speed data _VB is stored in RAM3.
Calculate the linear solenoid current starting from 0 and having an inversely proportional relationship to the auxiliary amount using the formula I=a ₀ V _B + a ₁ (1), and store the linear solenoid current data I at a predetermined address in the RAM 30. Write. This data I is then set in the down counter 31 as a count value corresponding to the duty ratio of the pulse signal energized to the solenoid coil 21 of the auxiliary force adjustment means 3 in step 118, which will be described later. The solenoid coil 21 of the auxiliary force adjustment means 3 is energized via the power amplifier circuit 32, and the power cylinder 18
The oil flow rate supplied to the engine is determined, and the auxiliary force is determined.

In this case, when the steering operation direction is to the right and the front wheels are facing to the left with respect to the straight-ahead direction, in other words, when the steering operation is performed so as to return to the neutral position of the steering after turning left, which is the so-called return direction. for,
The linear solenoid current I is set to increase as the vehicle speed increases, with only the vehicle speed as a parameter.
In other words, the auxiliary force is maintained at a constant value regardless of the magnitude of the steering operation speed at the same vehicle speed, as shown by the area partitioned by the vertical axis and the line L1 in FIG. 5, and by the broken line. It is made to decrease as it increases.

Therefore, when returning the steering after turning to the left, the assisting force is greater than before, so the steering can be quickly returned to the neutral position.

On the other hand, as a result of executing step 105, if it is determined that the steering operation position P is larger than the reference value _PC , that is, the front wheels are facing to the right with respect to the straight-ahead direction, then step 107 is executed, The steering operation speed data V _S and the standard steering operation speed data V _SO are each read from the RAM 30, and the steering operation speed V _S is read out from the RAM 30.
is larger than the standard steering operation speed _VSO .

If the steering operation speed V _S is less than or equal to the reference steering operation speed V _SO , then step 106 is executed as in the case of returning the steering as described above, and the linear solenoid current I is determined using only the vehicle speed as a parameter.

On the other hand, if the steering operation speed V _S is larger than the standard steering operation speed V _SO , then step 108 is executed, and the steering operation speed V _S is higher than the steering operation speed V _S ′ calculated at the previous program execution. Determine whether the steering operation speed is large or not, and determine whether the steering operation speed V _S is the steering operation speed
If it is larger than V _S ', the steering operation speed data V _S ' is updated in step 109, and on the other hand, if the steering operation speed V _S is less than or equal to the steering operation speed V _S ', the process proceeds to step 110. Steering operation speed data
After replacing the steering operation speed data V _S ' with a large value as V _S , step 119 is performed, and then step 111 or step 120 is executed.

In step 119, it is determined whether the steering operation position P is equal to or greater than the reference position θ ₀ corresponding to the set angle, that is, to which side of the boundary indicated by line L2 in FIG. 5 it belongs. Here, when the steering operation position P is equal to or greater than the reference position θ ₀ , it means, for example, a value just before the minimum turning radius determined by the vehicle speed and vehicle characteristics, and if it exceeds this value, there is a possibility that the vehicle will overturn. defined as meaning. The reference position θ ₀ is determined by θ ₀ =−K ₂ V _B +K ₃ (where K ₂ and K ₃ are positive constants) in accordance with the vehicle speed V _B , and is determined to be smaller as the speed increases.

In step 111, the linear solenoid current I is expressed by the formula I = (a ₂ V + _{a 3 )} | V _S | + C (2) (where a ₂ , a ₃ , C are constants), and the linear solenoid current data I is stored in RAM30.
write to the given address. And this data I
Similar to the data I obtained by executing step 106 described above, in step 118 described later, the data is set in the down counter 31 as a corresponding count value, and is sent to the solenoid coil 21 of the auxiliary force adjustment means 3 via the power amplification circuit 32. is energized, the oil flow rate supplied to the power cylinder 18 is determined, and the auxiliary force is determined.

On the other hand, when the steering angle exceeds the reference position θ ₀ (Fig. 5, strong region), in step 120, the vehicle speed is
Calculate the linear solenoid current using the formula I = (a ₄ V _B + a ₅ ) | P | + C' (where a ₄ , a ₅ , and C' are constants) using V _B and steering operation position P as parameters, The result is written to a predetermined address in RAM 30. This data is also applied to the counter 31 in step 118 for adjusting the auxiliary force.

In this way, when the steering operation direction is to the right, the front wheels are facing to the right with respect to the straight-ahead direction, and the steering operation speed is higher than the reference steering operation speed,
That is, when the steering operation is a right turn that is relatively similar to sudden handling, the linear solenoid current I
uses vehicle speed and steering operation speed as parameters, and increases as the vehicle speed and steering operation speed increase. In other words, the auxiliary force decreases as the steering operation speed increases at the same vehicle speed, as shown by the solid line in the area above the reference steering operation speed V _SO in Figure 5, and this decrease The degree increases as the vehicle speed increases.

Therefore, the sharper the right turn is made, the smaller the auxiliary force is, which makes it difficult for undesirable phenomena such as the vehicle to lean significantly due to sudden steering at high speed to occur, providing a stable steering feel. When the steering angle further increases and exceeds the reference angle (θ ₀ ), the assisting force is significantly reduced to prevent instability of the vehicle body due to excessive steering.

On the other hand, even if it is determined that the steering direction is to the left by executing step 104, the same processing as described above is executed when the steering direction is to the right. Here, steps 112 and 113 for executing this process,
Step 114, Step 115 and Step 1
16 perform the same functions as step 105, step 107, step 108, step 109, and step 110, respectively.

When the linear solenoid current I is determined in step 106, 111 or 120, step 117 is then executed to update the steering operation position data P.

Next, step 118 is executed, the linear solenoid current data I calculated in steps 106, 111, and 120 described above is read out from the RAM 30, a count value corresponding to the data I is set in the down counter 31, and step 101 is executed. return.

The down counter 31 to which the above count value has been set is at a high level until the count value is decremented by the clock signal and reaches ``0'', and after reaching ``0'', the down counter 31 remains at a high level until a new count value is set again. outputs a low-level pulse signal to the power amplification circuit 32, which amplifies the pulse signal and energizes the solenoid coil 21 of the auxiliary force adjustment means 3.

Melenoid coil 21 energized with a pulse signal
generates a magnetic attraction force corresponding to the duty ratio (pulse width) of the pulse signal, and this magnetic attraction force determines the amount of displacement of the electromagnetic plunger 20 and the flow rate of oil supplied to the power cylinder 18.

The above linear solenoid current I corresponds to the average current of the pulse signal energized to the solenoid coil 21, and the displacement amount of the electromagnetic plunger 22 and the above linear melenoid current I are in a positive proportional relationship. Needless to say.

In this embodiment, steps 104, 105, and 112 in the flowchart of FIG. 4 correspond to the steering operation direction determining means, and steps 106, 111, and 120 correspond to the adjusting means.

In the above-described embodiment, the reference steering operation speed was calculated based on the vehicle speed, and the assistance amount was also calculated using calculations, but the present invention is not limited to this, and the reference steering operation speed data The auxiliary amount data may be stored in advance in a storage means such as ROM as a data table in association with vehicle speed and steering operation speed, and this data table may be indexed when necessary.

Further, although the above embodiment includes the counter 31, the MPU 25 can
A configuration may be adopted in which the Hals signal having the calculated duty ratio is outputted to the power amplifier circuit 32 at regular intervals.

Also, MPU25, ROM29, and RAM30 are 1
Needless to say, a chip configuration may also be used.

〔Effect of the invention〕

As described above, in the present invention, when the steering operation direction determining means determines that the steering operation direction is a direction approaching the neutral position of the steering wheel while the vehicle is traveling at the same speed, the adjustment means moves the steering operation direction from the neutral position. The steering assist force is increased compared to when the steering wheel is moving away from the steering wheel, and the steering wheel is more easily stabilized near the neutral position, which has the excellent effect of improving the running stability of the vehicle.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of an embodiment of the present invention, Fig. 2
The figure is a schematic configuration diagram of the auxiliary force adjusting means in the same figure, Figure 3 is an electrical block diagram of this embodiment, Figure 4 is a flowchart for explaining the processing, and Figure 5 is the operation of this embodiment. The characteristic diagram and FIG. 6 each show an equivalent circuit of the steering operation detection means. 1... Vehicle speed signal generation means, 2... Control circuit, 3
...Auxiliary force adjustment means, 4...Steering signal generation means.

Claims (1)

[Claims] 1. Adapted to a power steering device that adjusts auxiliary force for steering operation in response to an electric signal,
Receiving the vehicle speed signal and the steering angle signal from the vehicle speed signal generating means that generates a vehicle speed signal corresponding to the running speed of the vehicle and the steering angle signal generating means generating a steering angle signal corresponding to the steering angle, In a control device for a power steering device that reduces the auxiliary force as the steering angle increases, the control device determines whether the direction of the steering operation is toward the neutral position of the steering wheel or away from the neutral position of the steering wheel. a steering direction determining means; and based on the results of the steering operation direction determining means,
When the same vehicle speed signal is generated by the vehicle speed signal generating means, adjusting means increases the auxiliary force when the steering direction is approaching the neutral position than when the steering direction is moving away from the neutral position. A control device for a power steering device, comprising: .