JP2005132168A - Power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power steering device capable of preventing a sense of incompatibility of a driver even when an input current command value is rapidly reduced. <P>SOLUTION: A steering angle system reduction rate Δbθ and a steering angular velocity system reduction rate Δbω per unit time of a steering angle system current command value Ibθ and a steering angular velocity system current command value Ibω are calculated. Magnitudes of the calculated reduction rates Δbθ and Δbω are compared with magnitudes of reference reduction rates Δaθ and Δaω, respectively. When Δaθ ≥ Δbθ, and Δaω ≥ Δbω, the actual steering angle system current command value Ibθ and the steering angular velocity system current command value Ibω are outputted. When Δaθ < Δbθ, and Δaω < Δbω, a steering angle system reference current command value Iaθ and a steering angular velocity system reference current command value Iaω based on the reference reduction rates Δaθ and Δaω are specified, and a value out of these specified steering angle system and steering angular system, whichever is the larger, is selected and outputted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power steering apparatus provided with a flow control valve for preventing energy loss.

As a power steering device provided with a flow control valve for preventing energy loss, there is one already disclosed in Patent Document 1 by the applicant of the present application.
As shown in FIG. 34, this conventional apparatus has one end of the spool 1 of the flow rate control valve V facing one pilot chamber 2 and the other end of the spool 1 facing the other pilot chamber 3.
A pump P is always in communication with the one pilot chamber 2 through a pump port 4. The one pilot chamber 2 communicates with the inflow side of the steering valve 9 that controls the power cylinder 8 via the flow path 6 → the variable orifice a → the flow path 7.

  On the other hand, in the other pilot chamber 3, a spring 5 is interposed and communicated with the inflow side of the steering valve 9 through a flow path 10 and a flow path 7. Therefore, the pilot chambers 2 and 3 communicate with each other through the flow path 6 → the variable orifice a → the flow path 7 → the flow path 10, and the pressure upstream of the variable orifice a is applied to one pilot chamber 2. The downstream pressure acts on the other pilot chamber 3. The opening of the variable orifice a is controlled by a solenoid current command value SI for the solenoid SOL.

The spool 1 maintains a position where the acting force of one pilot chamber 2 and the acting force of the other pilot chamber 3 and the spring force of the spring 5 are balanced, but at the balanced position, the opening degree of the tank port 11 is maintained. Is decided.
For example, when the pump P is driven by the operation of a pump drive source 12 such as an engine, pressure oil is supplied to the pump port 4 and a flow is generated in the variable orifice a. When a flow occurs in the variable orifice a in this way, a differential pressure is generated before and after that, and a pressure difference is generated in both pilot chambers 2 and 3 due to this differential pressure. Then, due to this pressure difference, the spool 1 moves from the normal position shown in the figure to the balance position against the spring 5.

  When the spool 1 moves from the normal position in this way, the opening degree of the tank port 11 increases, but the control flow rate QP guided from the pump P to the steering valve 9 side according to the opening degree of the tank port 11 at this time The distribution ratio with the return flow rate QT returned to the tank T or the pump P is determined. In other words, the control flow rate QP is determined according to the opening degree of the tank port 11.

  Thus, the fact that the control flow rate QP is controlled according to the opening degree of the tank port 11 ultimately determines the control flow rate QP according to the opening degree of the variable orifice a. This is because the moving position of the spool 1 that determines the opening of the tank port 11 is determined by the pressure difference between the pilot chambers 2 and 3, and this pressure difference is determined by the opening of the variable orifice a.

  Therefore, in order to control the control flow rate QP according to the vehicle speed and the steering situation, it is only necessary to control the opening of the variable orifice a, that is, the solenoid current command value SI for the solenoid SOL. This is because the opening of the variable orifice a can be arbitrarily controlled from the maximum to the minimum depending on the magnitude of the excitation current of the solenoid SOL.

On the other hand, the steering valve 9 to which the control flow rate QP is guided controls the supply amount to the power cylinder 8 in accordance with an input torque (steering torque) of a steering wheel (not shown). For example, if the steering torque is large, the switching amount of the steering valve 9 is increased to increase the supply amount to the power cylinder 8. Conversely, if the steering torque is small, the switching amount of the steering valve 9 is decreased to reduce the power cylinder. The supply amount to 8 is reduced. The power cylinder 8 exhibits a larger assist force as the pressure oil supply amount is larger, and the assist force is smaller as the supply amount is smaller.
Note that the switching amount of the steering torque and the steering valve 9 is set by a torsional reaction force such as a torsion bar (not shown).

  The required flow rate QM supplied to the power cylinder 8 as described above is controlled by the steering valve 9. The control flow rate QP supplied to the steering valve 9 is controlled by the flow rate control valve V as described above. Has been. Here, if the required flow rate QM required by the power cylinder 8 and the control flow rate QP determined by the flow rate control valve V are made as equal as possible, the energy loss on the pump P side can be kept low. This is because the energy loss on the pump P side is caused by the difference between the control flow rate QP and the required flow rate QM of the power cylinder 8.

  Therefore, in order to prevent the energy loss by making the control flow rate QP as close as possible to the required flow rate QM of the power cylinder 8, the opening degree of the variable orifice a is controlled in this conventional example. The opening degree of the variable orifice a is determined by the excitation current for the solenoid SOL as described above, and the controller C described below controls the excitation current.

  A steering angle sensor 14 and a vehicle speed sensor 15 are connected to the controller C. As shown in FIG. 35, the controller C specifies the current command value I1 based on the steering angle detected by the steering angle sensor 14, and also determines the current command value based on the steering angular velocity calculated by differentiating the steering angle. I2 is specified.

  The steering angle and the current command value I1 are determined on the basis of a theoretical value in which the relationship between the steering angle and the control flow rate QP is a linear characteristic. Further, the relationship between the steering angular velocity and the current command value I2 is also determined based on a theoretical value in which the relationship between the steering angular velocity and the control flow rate QP is a linear characteristic. However, the current command value I1 and the current command value I2 are both set to output zero unless the steering angle and the steering angular velocity exceed a certain set value. That is, when the steering wheel is in the neutral position or in the vicinity thereof, the current command values I1 and I2 are set to zero to make the neutral vicinity a dead band.

Further, the controller C outputs a steering angle current command value I3 and a steering angular velocity current command value I4 based on the detection value of the vehicle speed sensor 15.
The steering angle current command value I3 is set to 1 in the low speed range and to, for example, 0.6 in the maximum speed range. Further, the steering angular velocity current command value I4 is set to 1 in the low speed range and, for example, 0.8 in the maximum speed range. That is, the steering angle current command value controlled in the range of 1 to 0.8 is controlled by the steering angle current command value I3 controlled in the range of 1 to 0.6. It is made larger than I4.

  Since the steering angle current command value I3 is multiplied by the steering angle current command value I1, the multiplication result of the steering angle system current command value I5 decreases as the speed increases. . In addition, since the gain of the steering angle current command value I3 is set to be larger than the gain of the steering angular velocity current command value I4, the reduction rate increases as the speed increases. That is, the responsiveness is kept high in the low speed range, and the responsiveness is lowered in the high speed range. The reason why the responsiveness is changed in accordance with the vehicle speed in this way is generally that high responsiveness is not required during high-speed driving, and high responsiveness is almost always in the low speed range. .

On the other hand, for the current command value I2 based on the steering angular velocity, the steering angular velocity current command value I6 is output using the steering angular velocity current command value I4 as a limit value. The current command value I6 is also decreased according to the vehicle speed. However, since the gain of the steering angular velocity current command value I4 is smaller than the steering angular current command value I3, the rate of decrease of the current command value I6 is smaller than that of the current command value I5.
The reason why the limit value is set according to the vehicle speed is mainly to prevent the excessive assist force from being exerted during high-speed traveling.

The steering angle system current command value I5 and the steering angular velocity system current command value I6 output as described above are compared, and the larger value is adopted.
For example, when the vehicle is traveling at high speed, the steering is hardly operated suddenly, and therefore, the steering angle system current command value I5 is usually larger than the steering angular velocity system current command value I6. Therefore, in most cases, the current command value I5 for the steering angle system is selected during high speed traveling. In order to increase the safety and stability of the steering operation at this time, the gain of the current command value I5 is increased. That is, the higher the traveling speed, the higher the ratio of decreasing the control flow rate QP, thereby improving the safety and stability during traveling.

On the other hand, when the vehicle is traveling at a low speed, the steering is frequently operated suddenly. In many cases, the steering angular velocity is larger. For this reason, the current command value I6 of the steering angular velocity system is almost selected during low-speed traveling. When the steering angular velocity is large as described above, responsiveness is emphasized.
Therefore, when the vehicle is traveling at low speed, the gain of the current command value I6 of the steering angular velocity system is reduced with reference to the steering angular velocity in order to improve the operability of the steering operation, that is, the responsiveness. In other words, even when the traveling speed is increased to some extent, when the steering is suddenly operated, the control flow rate QP is sufficiently ensured to ensure responsiveness.

  The standby current command value I7 is added to the current command value I5 or I6 selected as described above. Then, a value obtained by adding the standby current command value I7 is output to the drive device 16 as a solenoid current command value SI.

  Since the standby current command value I7 is added in this way, the solenoid current command value SI is maintained at a predetermined magnitude even when the current command values based on the steering angle, the steering angular velocity, and the vehicle speed are all zero. Yes. Therefore, a predetermined flow rate is always supplied to the steering valve 9 side. From the viewpoint of preventing energy loss, if the required flow rate QM on the power cylinder 8 and steering valve 9 side is zero, it is ideal that the control flow rate QP of the flow control valve V is also zero.

  That is, to make the control flow rate QP zero means that the entire discharge amount of the pump P is returned from the tank port 11 to the pump P or the tank T. And since the flow path which returns from the tank port 11 to the pump P or the tank T is in the main body B and is very short, there is almost no pressure loss. Since there is almost no pressure loss, the driving torque of the pump P can be suppressed to the minimum, which leads to energy saving. From this point of view, when the required flow rate QM is zero, setting the control flow rate QP to zero is advantageous from the viewpoint of preventing energy loss.

Nevertheless, the reason why the standby flow rate QS composed of the standby current command value I7 is secured even when the required flow rate QM is zero is as follows.
First, it is for preventing the burn-in of the apparatus. That is, a cooling effect can be expected by circulating the standby flow rate QS to the apparatus.
Second, it is to ensure responsiveness. That is, if the standby flow rate QS is ensured as described above, the time to reach the target control flow rate QP can be shorter than when there is no standby flow rate QS. Since this time difference becomes responsiveness, the responsiveness can be improved by securing the standby flow rate QS.

  Thirdly, it is also for combating disturbances such as kickback and self-aligning torque. That is, when a drag due to disturbance, self-aligning torque or the like acts on the tire, it acts on the rod of the power cylinder 8. If the standby flow rate QS is not ensured, the tire will fluctuate due to the drag due to this disturbance and self-aligning torque. However, if the standby flow rate is secured, the tire will not wobble even if the above-described drag acts.

That is, since the pin of the power cylinder 8 is engaged with a pinion or the like for switching the steering valve 9, when the drag acts, the steering valve 9 is also switched, and the standby flow rate QS in a direction against the drag. Will be supplied. Therefore, if the standby flow rate QS is secured, the disturbance due to the kickback and the self-aligning torque can be countered.

Next, the operation of this conventional example will be described.
While the vehicle is traveling, a steering angle system current command value I5, which is a product of the solenoid current command value I1 based on the steering angle and the steering angle current command value I3, is output. At the same time, the steering angular velocity system current command value I6 is output. The current command value I6 is obtained by setting the steering angular velocity current command value I4 of the solenoid current command value I2 based on the steering angular velocity as a limit value.

  Then, the magnitude of the current command value I5 for the steering angle system and the current command value I6 for the steering angular velocity system is determined, and the standby current command value I7 is added to the larger current command value I5 or I6. The solenoid current command value SI at that time is determined. The solenoid current command value SI is mainly based on the steering angle system current command value I5 when the vehicle is traveling at high speed, and is mainly based on the steering angular velocity system current command value I6 when the vehicle is traveling at low speed.

A slit 13 is formed at the tip of the spool 1. The slit 13 allows one pilot chamber 2 and the variable orifice a to communicate with each other even when the spool 1 is in the normal position shown in the figure. That is, even when the spool 1 is in the normal position, the pressure oil supplied from the pump port 4 to the one pilot chamber 2 is supplied to the steering valve 9 via the slit 13 → the flow path 6 → the variable orifice a → the flow path 7. By supplying to the side, prevention of image sticking, prevention of disturbance such as kickback, and responsiveness are ensured.
In the figure, reference numerals 17 and 18 are throttles, and reference numeral 19 is a relief valve.

Japanese Patent Laid-Open No. 2001-260917 (pages 3 to 7, FIGS. 1 and 2)

  In the above-described conventional power steering apparatus, when the driver steers the steering wheel 60 deg in one direction from 60 deg in the other direction, for example, as shown in FIG. 36, current command values I1 and I2 of the steering angle system and the steering angular velocity system Returns to 0 in the vicinity of the neutral position and then returns again. That is, the current command values I1 and I2 draw a V shape near the neutral position, and the current command values I1 and I2 change rapidly. When such current command values I1 and I2 are directly output as the solenoid current command value SI, the control flow rate QP to the steering valve 9 also changes abruptly. Then, when the control flow rate QP to the steering valve 9 changes abruptly in this way, the steering torque required by the driver also changes abruptly, which causes the driver to feel uncomfortable.

  In addition, when the steering wheel is stopped in the large steering angle range, a current command value corresponding to the steering angle is output, so there is almost no sudden decrease in the control flow rate, but the steering wheel in the large steering angle range is generated. Is stopped in the small steering angle range, not only the current command value corresponding to the steering angle is decreased, but also the current command value for the steering angular velocity that has been output until then is not output. A sudden decrease occurs. When the current command value is suddenly reduced in this way, the control flow rate QP is suddenly reduced. As a result, there is a problem that the driver feels uncomfortable due to a sudden increase in the required steering torque.

  An object of the present invention is to provide a power steering device that does not give a driver a sense of incongruity even when an input current command value rapidly decreases.

  The present invention controls a steering valve for controlling a power cylinder, a variable orifice provided upstream of the steering valve, a solenoid for controlling the opening of the variable orifice, and a solenoid current command value SI for driving the solenoid. Controller, a steering state detection sensor connected to the controller and detecting a steering state such as a steering angle and a steering angular velocity, and pressure oil supplied from a pump according to the opening of the variable orifice and the tank Or a flow control valve that distributes to the pump side, and the controller presupposes a power steering device that specifies a solenoid current command value based on current command values corresponding to various signals from the steering situation detection sensor. .

  According to a first aspect of the present invention, in the apparatus, the controller includes a current command value characteristic storage unit, a delay control characteristic storage unit, and an execution unit, and the current command value characteristic storage unit includes a steering situation detection sensor. The actual steering angle system current command value Ibθ and the steering angular velocity system current command value Ibω based on the steering angle signal and the steering angular velocity signal are stored, and the delay control characteristic storage unit stores the steering angle system reference current command value Iaθ and the steering angular velocity. The steering angle system reference decrease rate Δaθ and the steering angular velocity system reference decrease rate Δaω that specify the system reference current command value Iaω are stored, and the execution unit stores the steering angle system current command value Ibθ and the steering angular velocity system current command value Ibω. The steering angle system reduction rate Δbθ and the steering angular velocity system reduction rate Δbω are calculated respectively, and the calculated reduction rates Δbθ and Δbω are compared with the reference reduction rates Δaθ and Δaω. In comparison, when Δaθ ≧ Δbθ and Δaω ≧ Δbω, the actual steering angle system current command value Ibθ and steering angular velocity system current command value Ibω are output, respectively, and when Δaθ <Δbθ and Δaω <Δbω, the reference The steering angle system reference current command value Iaθ and the steering angular velocity system reference current command value Iaω based on the decrease rates Δaθ and Δaω are specified, and any one of the specified steering angle system value and steering angular velocity system value is selected. The larger value is selected and output.

  In the second invention, the steering angle system reference reduction rate Δaθ and the steering angular speed system reference reduction rate Δaω in the first invention are kept at the minimum values when the vehicle speed is in the low speed range, and the vehicle speed increases in the medium speed range. It is characterized by increasing according to the maximum value in the high speed range.

  The third invention maintains the maximum value of the steering angle system reference decrease rate Δaθ in the first invention when the steering angular velocity is in a small region, and decreases in the middle region as the steering angular velocity increases. While the vehicle speed is in the low speed range, the steering angular velocity system reference reduction rate Δaω remains at the minimum value, increases in the medium speed range as the vehicle speed increases, and reaches the maximum value in the high speed range. It is characterized by keeping.

  In a fourth aspect of the invention, the steering angle reference reduction rate Δaθ in the first aspect of the invention is kept at a minimum value when the vehicle speed is in a low speed range, and increases with an increase in the vehicle speed in a medium speed range. Maintains the maximum value, while the steering angular velocity system reference decrease rate Δaω keeps the minimum value when the steering angle is in the small region, increases with the increase of the steering angle when it is in the middle region, and is the maximum value in the large region It is characterized by keeping.

  In the fifth aspect of the invention, the steering angle system reference decrease rate Δaθ in the first aspect of the invention is maintained at the highest value when the steering angular velocity is in a small region, and is decreased in the middle region as the steering angular velocity is increased. While the steering angle is kept at the minimum value, the steering angular velocity system reference decrease rate Δaω is kept at the minimum value when the steering angle is in the small region, increases with the increase of the steering angle when it is in the middle region, and is highest in the large region. It is characterized by keeping the value.

According to the first invention, even when the input steering angle system current command value and the steering angular velocity system current command value are suddenly decreased, a sudden fluctuation of the output current command value is caused by applying the delay control. Alleviated.
Accordingly, the rate of decrease in the supply flow rate to the steering valve can be controlled to be reduced, and the uncomfortable feeling that has conventionally occurred due to a sudden change in the required steering torque can be prevented.

  According to the second aspect, since the steering angle system reference reduction rate and the steering angular velocity system reduction rate are made variable according to the vehicle speed, fine control suitable for the actual traveling state can be performed.

  According to the third aspect of the invention, the steering angle reference reduction rate Δaθ is made variable according to the steering angular velocity, and the steering angular velocity system reference reduction rate Δaω is made variable according to the vehicle speed. Can do.

  According to the fourth aspect of the invention, the steering angle system reference decrease rate Δaθ is made variable according to the vehicle speed, and the steering angle speed system reference decrease rate Δaω is made variable according to the steering angle, so that fine control suitable for the actual running state is achieved. Can do.

  According to the fifth aspect of the invention, the steering angle system reference decrease rate Δaθ is made variable according to the steering angular velocity, and the steering angular velocity system reference decrease rate Δaω is made variable according to the steering angle. Can control.

1 to 5 show a first embodiment of the present invention. Since the configuration other than the controller C shown in FIG. 34 is exactly the same as the conventional example, only the controller C will be described below.
As shown in FIG. 1, the controller C specifies the current command value I1 based on the steering angle detected by the steering angle sensor 14, and also determines the current command value I2 based on the steering angular velocity calculated by differentiating the steering angle. Is identified. However, a steering angular velocity sensor may be provided separately, and the current command value I2 may be specified based on the steering angular velocity detected by the steering angular velocity sensor.

  The steering angle and the current command value I1 are determined based on a theoretical value in which the relationship between the steering angle and the control flow rate QP is a linear characteristic. Further, the relationship between the steering angular velocity and the current command value I2 is also determined based on a theoretical value in which the relationship between the steering angular velocity and the control flow rate QP is a linear characteristic.

  Further, the controller C outputs a steering angle current command value I3 and a steering angular velocity current command value I4 based on the detection value of the vehicle speed sensor 15. The current command value I3 decreases when the vehicle speed is zero or in the extremely low speed range, and outputs 1 when the vehicle speed exceeds a certain speed. Further, the current command value I4 is a value larger than 1 when the vehicle speed is zero or in the extremely low speed range, and 1 when the vehicle speed exceeds a certain speed. Of these current command values, the current command value I3 is multiplied by the current command value I1 of the steering angular system, and the current command value I4 is multiplied by the current command value I2 of the steering angular velocity system.

  The reason why the current command value I3 based on the vehicle speed is multiplied as described above is to prevent energy loss when the vehicle is stopped or in the extremely low speed range with the steering wheel turned off. For example, when entering the garage, the engine may be stopped for a while with the steering wheel turned off. Even in such a case, the current command value I1 corresponding to the steering angle is the solenoid current command value SI. As a result, a wasteful flow rate is supplied to the steering valve 9 side. In order to prevent such waste, the current command value I3 is multiplied to reduce the steering angle system current command value I1 when the vehicle speed is 0 or extremely low.

  However, if the current command value I3 is reduced as described above, the responsiveness when starting to turn the steering wheel from the state in which the steering wheel is maintained deteriorates, so that the current command value I4 that outputs a large value at the vehicle speed of 0 or extremely low speed range. Is multiplied by the current command value I2 of the steering angular velocity system to ensure responsiveness.

When the current command value I3 based on the vehicle speed is multiplied, the current command value (I1 × I3) after the multiplication is subjected to delay control in the delay control unit, and the current command value after the delay control is further calculated based on the vehicle speed. Multiply by the set current command value I5.
Further, the current command value (I2 × I4) of the steering angular velocity system is also subjected to delay control by the delay control unit, and the current command value after this delay control is multiplied by the current command value I6 set based on the vehicle speed. .
The function of the delay control unit will be described in detail later.

  The current command values I5 and I6 are set to output 1 in the low speed range and output a decimal value less than 1 in the maximum speed range. Therefore, the input value is output as it is in the low speed range, but the output value decreases as the speed increases. That is, the responsiveness is kept high in the low speed range, and the responsiveness is lowered in the high speed range. The reason why the responsiveness is changed in accordance with the vehicle speed in this way is generally that high responsiveness is not required during high-speed driving, and high responsiveness is almost always in the low speed range. .

The current command values after the multiplication are output with current command values I7 and I8 set based on the vehicle speed as limit values. That is, when the value after multiplication exceeds the current command values I7 and I8 corresponding to the vehicle speed at that time, the excess is cut and the current command value within the limit value is output. I have to. The limit value based on the vehicle speed is set in this way in order to prevent an excessive assist force from being exerted during high speed traveling.
The current command values I7 and I8 are also decreased according to the vehicle speed, but the gain is set smaller than the gain of the current command values I5 and I6.

Next, the steering angle system current command value suppressed within the limit value as described above is compared with the steering angular velocity system current command value, and the larger value is adopted. The larger current command value becomes the basic current command value Id.
When the basic current command value Id is obtained in this way, the standby current command value Is is added to the basic current command value Id. However, instead of adding the standby current command value Is as it is, a value obtained by multiplying the standby current command value Is by the current command value I9 set based on the vehicle speed is added.

The current command value I9 based on the vehicle speed is 1 in the low speed range, but gradually decreases as the vehicle speed increases in the medium speed range. Then, the minimum value is kept at the high speed range. Therefore, a value obtained by multiplying the current command value I9 based on the vehicle speed by the current command value Is for standby is output as it is in the low speed range and gradually decreases from the medium speed range to the high speed range. In the high speed range, the minimum value is maintained. If the standby current command value is reduced in the high speed range, waste of the standby flow rate in the high speed range can be prevented.
Even in the high speed range, the value obtained by multiplying the current command value I9 and the current command value Is is set so as not to become zero.

  When the standby current command value (Is × I9) is added to the basic current command value Id as described above, the added value is output to the drive device 16 (see FIG. 34) as the solenoid current command value SI. Then, the driving device 16 outputs an exciting current corresponding to the solenoid current command value SI to the solenoid SOL.

  As described above, the solenoid current command value SI is controlled. For example, as shown in FIG. 2, the small steering angle on the right side slightly exceeds the neutral position from the state where the steering wheel is steered to the left side. In the case of the conventional example where there is no delay control, the steering angle system current command value Ibθ changes as shown by the solid line in FIG. That is, the steering angle system current command value Ibθ gradually decreases as the steering angle decreases, and maintains a constant level when a predetermined steering angle is reached. On the other hand, the current command value Ibω of the steering angular velocity system maintains a constant value while operating the steering as shown by a broken line, and rapidly decreases when the steering wheel operation is stopped.

  Assuming that the solenoid current command value SI is controlled based on the current command value of the steering angular velocity system, the assist force by the power cylinder 8 rapidly decreases when the operation of the steering wheel is stopped. When the assist force decreases rapidly in this way, the steering or holding torque required to steer or hold the steering wheel increases rapidly as shown by the broken line in FIG. If the steering torque increases rapidly in this way, the steering cannot be reliably performed or the driver feels uncomfortable.

Therefore, in order to prevent such inconvenience, the delay control unit performs its function. The delay control unit will be described below.
The delay control unit includes a current command value characteristic storage unit, a delay control characteristic storage unit, and an execution unit that executes delay control.
The current command value characteristic storage unit has a function of storing a steering angle system current command value (I1 × I3) and a steering angular velocity system current command value (I2 × I4). Hereinafter, the steering angle system current command value (I1 × I3) is referred to as “actual steering angle system current command value Ibθ”, and the steering angular velocity system current command value (I2 × I4) is represented by “ The actual steering angular velocity system current command value Ibω ”.

  The delay control characteristic storage unit stores a steering angle system reference decrease rate Δaθ and a steering angular velocity system reference decrease rate Δaω. The steering angle system reference decrease rate Δaθ is a value for specifying the steering angle system reference current command value Iaθ indicated by the two-dot chain line in FIG. 3, and the steering angular velocity system reference decrease rate Δaω is indicated by the one-dot chain line in FIG. This is a value for specifying the steering angular velocity system reference current command value Iaω, and these reference reduction rates Δaθ and Δaω are determined by experiments or the like.

  FIG. 5 shows a control flow by the delay control unit, but the control content of the steering angle system and the control content of the steering angular velocity system are basically the same. Therefore, hereinafter, the steering angle system control and the steering angular velocity system control will be described using FIG. 5 in common. However, in FIG. 5, the symbols “θ” representing the steering angle system and “ω” representing the steering angular velocity system are omitted.

First, the delay control of the steering angle system will be described.
In step 0, the steering angle system reference reduction rate Δaθ is captured and stored in the delay control characteristic storage unit. Next, in step 1, the actual steering angle system current command value Ibθ (t1) at time t1 is detected, and in step 2, the time t1 and the detected value Ibθ (t1) are stored.
In step 3, an actual steering angle system current command value Ibθ (t2) at a time t2 after a predetermined time has elapsed is detected. In step 4, the time t2 and the detected value Ibθ (t2) are stored.

  In step 5, the steering angle system current command value Ibθ (t1) is compared with the steering angle system current command value Ibθ (t2). When Ibθ (t2) is smaller than Ibθ (t1), that is, when the current command value decreases, the process proceeds to step 6 to decrease the actual steering angle system current command value Ibθ per unit time Δbθ. Is calculated.

  In step 7, the reduction rate Δbθ is compared with a prestored steering angle system reference reduction rate Δaθ. Then, when it is determined that the steering angle system reference decrease rate Δaθ is smaller than the actual decrease rate Δbθ, the process proceeds to step 8 to output the steering angle system reference current command value Iaθ based on the steering angle system reference decrease rate Δaθ. . When the steering angle system current command value Iaθ is output in this way, a value larger than the actual steering angle system current command value Ibθ is output.

  In step 9, the steering angle system current command value Iaθ is compared with the actual steering angle system current command value Ibθ (t2). When the steering angle system reference current command value Iaθ is larger than the actual steering angle system current command value Ibθ (t2), the process returns to step 8, and the steering angle system reference current based on the steering angle system reference decrease rate Δaθ continues. Continue to output the command value Iaθ.

On the other hand, when the steering angle system reference current command value Iaθ becomes smaller than the actual steering angle system current command value Ibθ (t2), the routine proceeds to step 10, and the control is performed with the actual steering angle system current command value Ibθ (t2). Will do.
In step 11, t2 is replaced with t1, and Ib (t2) is replaced with Ib (t1). And it returns to step 2 again and repeats the said procedure.

On the other hand, if it is determined in step 5 above that Ibθ (t2) is greater than Ibθ (t1), that is, if the current command value has increased, the process proceeds to step 10 to determine the actual steering angle system current. The command value Ibθ (t2) is output.
Further, when it is determined in step 7 that the actual steering angle system decrease rate Δbθ is smaller than the steering angle system reference decrease rate Δaθ, the process proceeds to step 10 and the actual steering angle system current command value Ibθ (t2). ) Is output. That is, when the current command value decreases but does not decrease so rapidly, control is performed with the actual steering angle system current command value Ibθ (t2).

Next, the delay control of the steering angular velocity system will be described.
As shown in FIG. 5, in step 0, the steering angular velocity system reference decrease rate Δaω is taken in and stored in the delay control characteristic storage unit. Next, in step 1, the actual steering angular velocity system current command value Ibω (t1) at time t1 is detected, and in step 2, the time t1 and the detected value Ibω (t1) are stored.
In step 3, an actual steering angular velocity system current command value Ibω (t2) at a time t2 after a predetermined time has elapsed is detected. In step 4, the time t2 and the detected value Ibω (t2) are stored.

  In step 5, the steering angular velocity system current command value Ibω (t1) is compared with the steering angular velocity system current command value Ibω (t2). When Ibω (t2) is smaller than Ibω (t1), that is, when the current command value is decreased, the process proceeds to step 6 to decrease the actual steering angular velocity system current command value Ibω per unit time Δbω. Is calculated.

  In step 7, the decrease rate Δbω is compared with a prestored steering angular velocity system reference decrease rate Δaω. Then, when it is determined that the steering angular velocity system reference reduction rate Δaω is smaller than the actual reduction rate Δbω, the routine proceeds to step 8 where the steering angular velocity system reference current command value Iaω based on the steering angular velocity system reference reduction rate Δaω is output. . When the steering angular velocity system current command value Iaω is output in this way, a value larger than the actual steering angular velocity system current command value Ibω is output.

  In Step 9, the steering angular velocity system reference current command value Iaω is compared with the actual steering angular velocity system current command value Ibω (t2). If the steering angular velocity system reference current command value Iaω is larger than the actual steering angular velocity system current command value Ibω (t2), the process returns to step 8 and the steering angular velocity system reference current based on the steering angular velocity system reference decrease rate Δaω is continued. Continue to output the command value Iaω.

On the other hand, when the steering angular velocity system reference current command value Iaω is smaller than the actual steering angular velocity system current command value Ibω (t2), the routine proceeds to step 10 where the actual steering angular velocity system current command value Ibω (t2) is controlled. Will do.
In step 11, t2 is replaced with t1, and Ib (t2) is replaced with Ib (t1). And it returns to step 2 again and repeats the said procedure.

On the other hand, if it is determined in step 5 that Ibω (t2) is larger than Ibω (t1), that is, if the current command value has increased, the process proceeds to step 10 to determine the actual steering angular velocity system current. Command value Ibω (t2) is output.
Further, when it is determined in step 7 that the actual steering angular velocity system reduction rate Δbω is smaller than the steering angular velocity system reference reduction rate Δaω, the process proceeds to step 10, and the actual steering angular velocity system current command value Ibω (t2 ) Is output. That is, when the current command value is decreasing but not decreasing so rapidly, the actual steering angular velocity system current command value Ibω (t2) is used for control.

  As described above, according to the first embodiment, the actual steering angle system current command value Ibθ and the actual steering angular velocity system current command value Ibω are decreased, and the decrease rate Δbθ and Only when it is determined that Δbω is larger than the steering angle system reference reduction rate Δaθ and the steering angular velocity system reference reduction rate Δaω, the steering angle system reference current based on the steering angle system reference reduction rate Δaθ and the steering angular velocity system reference reduction rate Δaω. The command value Iaθ and the steering angular velocity system reference current command value Iaω are output.

  In this way, as indicated by the two-dot chain line and the one-dot chain line in FIG. 4, the steering torque required by the driver also gradually increases, so the actual steering angle system current command value Ibθ or the steering angular velocity system current command value An abrupt increase in steering torque that occurs when based on Ibω can be suppressed. Therefore, it is possible to stabilize the steering state and prevent the driver from feeling uncomfortable.

In the second embodiment shown in FIGS. 6 to 10, the steering angle system reference reduction rate Δaθ and the steering angular speed system reference reduction rate Δaω in the delay control unit are made variable in accordance with the vehicle speed. That is, in this second embodiment, as shown in FIG. 10, the procedure from step 1 to step 6 is the same as that of the first embodiment, but the vehicle speed v is detected in step 7, and the vehicle speed is detected in step 8. The steering angle system reference reduction rate Δaθ and the steering angular velocity system reference reduction rate Δaω corresponding to v are set.
Note that the procedure from Step 9 to Step 13 corresponds to the procedure from Step 7 to Step 11 of the first embodiment, and the contents thereof are the same.

  In step 8, as shown in FIG. 6, a coefficient K1 (K2) determined according to the vehicle speed is multiplied by the reference reduction rate Δaθ (Δaω). The coefficient K1 (K2) determined according to the vehicle speed is a constant value less than 1 when the vehicle speed is in the low speed range, but increases as the vehicle speed increases when the vehicle speed is in the middle speed range. In the high speed range, the coefficient K1 (K2) becomes 1.

  Therefore, as shown in FIG. 7, when the steering wheel is steered from the left side to the right side, the steering angle system reference current command value Iaθ determined by the steering angle system reference reduction rate Δaθ is, as shown by the two-dot chain line in FIG. When the vehicle speed is in the low speed range, the current command value Iaθ1 has a gentle slope, and when the vehicle speed is in the high speed range, the current command value Iaθ2 has a steep slope. If the vehicle speed is in the middle speed range, the current command value Iaθ3 has a slope between the current command values Iaθ1 and Iaθ2.

  Further, the steering angular velocity system reference current command value Iaω determined by the steering angular velocity system reference reduction rate Δaω becomes a current command value Iaω1 having a gentle slope when the vehicle speed is in a low speed region, as shown by a one-dot chain line in FIG. In the high speed range, the current command value Iaω2 has a steep slope. If the vehicle speed is in the middle speed range, the current command value Iaω3 has a slope between the current command values Iaω1 and Iaω2.

If the reference decrease rates Δaθ and Δaω when the vehicle speed is in the low speed range are reduced, the change in the output current command value is reduced, so that a rapid increase in steering torque in the low speed range is suppressed as shown in FIG. can do. Therefore, it is possible to smoothly perform steering when the vehicle is in a low speed range.
On the other hand, when the vehicle speed is changed from the medium speed range to the high speed range, the reference decrease rates Δaθ and Δaω increase accordingly, so that the change in the output current command value also increases. However, in the high speed range, the change in the current command value As a result, the steering wheel feels neutral, and the handling stability is improved accordingly.

  That is, according to the second embodiment, the reference reduction rates Δaθ and Δaω are kept at the minimum values when the vehicle speed is in the low speed range, increase with the increase of the vehicle speed in the medium speed range, and are highest in the high speed range. Since the control is performed so as to maintain the value, finer control suitable for the actual running state is possible.

  In the third embodiment shown in FIGS. 11 to 15, the steering angle system reference decrease rate Δaθ in the steering angle system delay control unit is made variable in accordance with the steering angular velocity, and the steering angle speed system reference in the steering angle speed system delay control unit is made. The decrease rate Δaω is made variable according to the vehicle speed. That is, in the third embodiment, the steering angle reference reduction rate Δaθ in the second embodiment is made variable in accordance with the steering angular velocity instead of the vehicle speed. Therefore, in FIG. 15 showing the delay control of the steering angle system, the procedure from Step 1 to Step 6 and the procedure from Step 9 to Step 13 are the same as those in the second embodiment. In step 8, the steering angle system reference reduction rate Δaθ corresponding to the steering angular velocity is set.

  In step 8, as shown in FIG. 11, a coefficient K3 determined according to the steering angular velocity is multiplied by the reference reduction rate Δaθ. The coefficient K3 determined according to the steering angular velocity maintains a value of 1 when the steering angular velocity is a small region, and decreases according to the steering angular velocity when the steering angular velocity is a middle region. When the steering angular velocity is in a large region, the coefficient K3 is less than 1.

  Therefore, as shown in FIG. 12, when the steering wheel is steered from the left side to the right side, the reference current command value Iaθ determined by the steering angle system reference reduction rate Δaθ is, as shown by the two-dot chain line in FIG. If it is in the small region, the current command value Iaθ1 has a steep slope, and if the steering angular velocity is in the large region, the current command value Iaθ2 has a gentle slope. If the steering angular velocity is in the middle region, the current command value Iaθ3 having a slope between the Iaθ1 and Iaθ2 is obtained.

  If the reference decrease rate Δaθ in the large region of the steering angular velocity is reduced, the change in the output current command value Iaθ2 is reduced. Therefore, as shown in FIG. 14, the steering angular velocity suppresses a rapid increase in steering torque in the large region. can do. The case where the steering angular velocity is in a large region is mostly the case where the vehicle is at a low speed. Therefore, by reducing the reference reduction rate Δaθ when the steering angular velocity is in the large region, steering when the vehicle is in the low speed region can be performed smoothly.

  On the other hand, if the reference decrease rate Δaθ increases as the steering angular velocity decreases, the change in the current command value also increases, resulting in a neutral feel of the steering wheel. However, the steering angular velocity decreases. It can be guessed that there is a tendency to become. Therefore, by increasing the reference reduction rate Δaθ as the steering angular velocity decreases, the steering stability when the vehicle speed is in the high speed range can be improved.

  As described above, according to the third embodiment, the steering angular speed reference reduction rate Δaω is variably controlled according to the vehicle speed, while the steering angular speed reference reduction rate Δaθ is set so that the steering angular speed is in a small region. The maximum value is maintained, and the control is performed so as to decrease as the steering angular velocity increases in the middle region and to maintain the minimum value in the large region, so that finer control according to the actual traveling state is possible.

  In the fourth embodiment shown in FIGS. 16 to 19, the steering angle system reference decrease rate Δaθ in the steering angle system delay control unit is made variable according to the vehicle speed, and the steering angle speed system reference decrease in the steering angle speed system delay control unit is made. The rate Δaω is made variable according to the steering angle. That is, in the fourth embodiment, the steering angular velocity system reference reduction rate Δaω in the second embodiment is made variable according to the steering angle instead of the vehicle speed. Therefore, in FIG. 10 showing the delay control of the steering angular velocity system, the procedure from Step 1 to Step 6 and the procedure from Step 9 to Step 13 are the same as those in the second embodiment. In step 8, the steering angular velocity system reference decrease rate Δaω corresponding to the steering angle is set.

In step 8, as shown in FIG. 16, a coefficient K6 determined according to the steering angle is multiplied by the reference reduction rate Δaω. The coefficient K6 determined according to the steering angle is less than 1 if the steering angle is in the small region, but increases as the steering angle increases when the steering angle is in the middle region. When the steering angle becomes a large region, the coefficient K6 maintains a value of 1.
Therefore, as shown in FIG. 17, when the steering wheel is steered from the left side to the right side, the reference current command value Iaω determined by the steering angular velocity system reference reduction rate Δaω has a small steering angle as shown by the one-dot chain line in FIG. When the steering angle is in the region, the current command value Iaω1 has a gentle slope. When the steering angle is in the large region, the current command value Iaω2 has a steep slope.

  If the steering angular velocity system reference decrease rate Δaω when the steering angle is in the small region is reduced, the change in the output current command value is reduced. Therefore, as shown in FIG. 19, the steering angle is in the small region. An abrupt increase in steering torque can be suppressed. Therefore, an increase in the steering torque in the small steering angle region is suppressed, and smooth steering is possible.

On the other hand, as the steering angle increases, when the steering angular velocity system reference decrease rate Δaω increases, the decrease rate of the current command value also increases, resulting in a neutral feeling of the steering wheel. Therefore, steering stability can be improved.
As described above, according to the fourth embodiment, the steering angle system reference decrease rate Δaθ is variably controlled according to the vehicle speed, while the steering angle speed system reference decrease rate Δaω is set so that the steering angle is in a small region. Sometimes the minimum value is maintained, and when it is in the middle region, it increases with the increase of the steering angle, and in the large region, it is configured to maintain the maximum value, so finer control according to the actual running state is possible It becomes.

  In the fifth embodiment shown in FIGS. 20 to 23, the steering angle system reference decrease rate Δaθ in the steering angle system delay control unit is made variable according to the steering angular velocity, and the steering angle speed system reference in the steering angle speed system delay control unit is made. The decrease rate Δaω is made variable according to the steering angle. That is, the fifth embodiment is a combination of the steering angle system delay control portion in the third embodiment and the steering angular velocity system delay control portion in the fourth embodiment.

  The control flow in the steering angle system is the same as that in the third embodiment, and a coefficient K7 determined according to the steering angular velocity is multiplied by the reference reduction rate Δaθ. The coefficient K7 maintains a value of 1 when the steering angular velocity is in a small region, and decreases according to the steering angular velocity when the steering angular velocity is in a middle region. When the steering angular velocity is in a large region, the coefficient K7 is less than 1.

  The control flow in the steering angular velocity system is the same as that in the fourth embodiment. That is, the coefficient K8 determined according to the steering angle is multiplied by the reference reduction rate Δaω. The coefficient K6 is less than 1 when the steering angle is in the small region, but increases as the steering angle increases when the steering angle is in the middle region. When the steering angle becomes a large region, the coefficient K6 maintains a value of 1.

  According to the fifth embodiment, as shown in FIG. 21, when the steering wheel is steered from the left side to the right side, the reference current command value Iaθ determined by the steering angle system reference decrease rate Δaθ is indicated by a two-dot chain line in FIG. As shown, when the steering angular velocity is in a small region, the current command value Iaθ1 has a steep slope, and when the steering angular velocity is in a large region, the current command value Iaθ2 has a gentle slope. If the steering angular velocity is in the middle region, the current command value Iaθ3 has a slope between Iaθ1 and Iaθ2.

  Further, the reference current command value Iaω determined by the steering angular velocity system reference reduction rate Δaω becomes a current command value Iaω1 having a gentle slope if the steering angle is in a small region, as shown by a one-dot chain line in FIG. In this case, the current command value Iaω2 has a steep slope.

  As described above, in the steering angle system, if the steering angle system reference decrease rate Δaθ when the steering angular velocity is in a large region is reduced, the change in the output steering angle system current command value is reduced. As shown, a sudden increase in steering torque when the steering angular velocity is in a large region can be suppressed. When the steering angular velocity is in the large region, the vehicle speed is almost always low. Therefore, when the steering angular velocity is in the large region, the vehicle is operated in the low speed region by reducing the steering angle system reference decrease rate Δaθ. Steering can be performed smoothly.

  Further, as the steering angle system reference decrease rate Δaθ increases as the steering angular velocity decreases, the change in the current command value also increases, resulting in a neutral feeling of the steering wheel. However, the steering angular velocity decreases because the vehicle It can be inferred that it tends to be in the high speed range. Therefore, by increasing the reference reduction rate Δaθ as the steering angular velocity decreases, it is possible to improve the steering stability when the vehicle is in the high speed range.

On the other hand, in the steering angular velocity system, if the steering angular velocity system reference decrease rate Δaω when the steering angle is in a small region is reduced, the change in the output current command value is reduced. Therefore, as shown in FIG. A sudden increase in the steering torque when is in a small region can be suppressed. Therefore, an increase in the steering torque in the small steering angle region is suppressed, and smooth steering is possible.
Further, as the steering angle increases, when the steering angular velocity system reference decrease rate Δaω increases, the decrease rate of the current command value also increases, so that the steering wheel feels neutral. Therefore, steering stability can be improved.

  That is, according to the fifth embodiment, the steering angle system reference decrease rate Δaθ is maintained at the highest value when the steering angular velocity is in the small region, and is decreased in accordance with the increase of the steering angular velocity in the middle region, and in the large region. While maintaining the minimum value, the steering angular velocity system reference decrease rate Δaω is kept at the minimum value when the steering angle is in the small region, and increases with the increase of the steering angle when the steering angle is in the middle region. Therefore, finer control according to the actual running state is possible.

  The sixth embodiment shown in FIGS. 24 to 28 is provided with a delay control unit and a current command value maintaining unit to prevent a sudden change in the solenoid current command value SI causing discomfort. is there. That is, in the sixth embodiment, as shown in FIG. 24, a predetermined control is applied to the current command value (I1 × I3) of the steering angle system by the delay control unit or the current command value maintaining unit, and the steering angular velocity system A predetermined control is applied to the current command value (I2 × I4) by the delay control unit or the current command value maintaining unit.

Since the function of the delay control unit is the same as that of the delay control unit of the first to fifth embodiments, a detailed description thereof is omitted here.
On the other hand, the current command value maintaining unit has a function of maintaining a constant current command value to be output, but the function is turned on and off by a signal from the vehicle speed determination unit.
The vehicle speed determination unit determines that the vehicle speed is low when the vehicle speed detected by the vehicle speed sensor is equal to or less than a predetermined value, and turns on the function of the current command value maintaining unit at this time. Further, when the vehicle speed detected by the vehicle speed sensor exceeds a certain value, it is determined that the vehicle speed is high, and at this time, the function of the current command value maintaining unit is turned off.

  FIG. 28 shows the control flow of the sixth embodiment, but the control content of the steering angle system and the control content of the steering angular velocity system are basically the same. Therefore, hereinafter, the steering angle system control and the steering angular velocity system control will be described using FIG. 28 in common. In FIG. 28, however, the symbols “θ” representing the steering angle system and “ω” representing the steering angular velocity system are omitted.

First, the delay control of the steering angle system will be described.
In step 0, the steering angle system reference reduction rate Δaθ is taken in and stored in the delay control characteristic storage unit. Next, in step 1, the actual steering angle system current command value Ibθ (t1) at time t1 is detected, and in step 2, the time t1 and the detected value Ibθ (t1) are stored.
In step 3, an actual steering angle system current command value Ibθ (t2) at a time t2 after a predetermined time has elapsed is detected. In step 4, the time t2 and the detected value Ibθ (t2) are stored.

  In step 5, the steering angle system current command value Ibθ (t1) is compared with the steering angle system current command value Ibθ (t2). When Ibθ (t2) is smaller than Ibθ (t1), that is, when it is determined that the current command value has decreased, the routine proceeds to step 6 where the actual steering angle system current command value Ibθ per unit time is determined. A steering angle system reduction rate Δbθ is calculated.

  In step 7, the vehicle speed is detected, and in step 8, the vehicle speed determination unit determines whether the vehicle speed is low or high. If the vehicle speed determination unit determines that the vehicle speed is high, the process proceeds to step 9 to set the steering angle system reference decrease rate Δaθ. When the steering angle system reference decrease rate Δaθ is set in this way, in step 10, the steering angle system reference decrease rate Δaθ is compared with the actual steering angle system reference decrease rate Δbθ. When it is determined that the steering angle system reference reduction rate Δaθ is smaller than the actual steering angle system reduction rate Δbθ, the process proceeds to step 11 and a steering angle system reference current command based on the steering angle system reference reduction rate Δaθ. The value Iaθ is output.

  When the steering angle system reference current command value Iaθ is output in this way, a value larger than the actual steering angle system current command value Ibθ is output as shown by a two-dot chain line in FIG. Therefore, as shown in FIG. 27, since a sudden increase in steering torque can be suppressed, a sense of discomfort given to the driver can be prevented.

  In step 12, the steering angle system reference current command value Iaθ is compared with the actual steering angle system current command value Ibθ (t2), and the steering angle system reference current command value Iaθ is compared with the actual steering angle system current command value Ibθ ( If it is greater than t2), the vehicle speed is detected in step 13, and it is determined in step 14 whether the vehicle speed is high or low. Then, when the speed is high, the process returns to the above step 10, and when the steering angle system reduction rate Δaθ is smaller than the actual steering angle system reduction rate Δbθ, the steering angle system reference current command based on the steering angle system reference reduction rate Δaθ. Control will continue with the value Iaθ.

  On the other hand, if it is determined at step 14 that the speed is low, the routine proceeds to step 17 where the steering angle system current command value Iaθ output at that time is maintained as shown in FIG. If the steering angle system current command value Iaθ is maintained in this way, as shown in FIG. 27, the steering torque does not increase any more, so that a sense of incongruity caused by an increase in the steering torque can be prevented more reliably.

  In step 18, it is determined whether or not the steering angle system reference current command value Iaθ maintained constant is larger than the actual steering angle system current command value Ibθ. If the steering angle system reference current command value Iaθ is larger than the actual steering angle system current command value Ibθ (t2), the process proceeds to step 16 where t2 is replaced with t1 and Ibθ (t2) is replaced with Ibθ (t1). replace. And it returns to step 2 again and repeats the said procedure.

  On the other hand, when the steering angle system current command value Iaθ maintained constant in step 18 becomes equal to or less than the actual steering angle system current command value Ibθ (t2), the actual steering angle system current command value Ibθ (t2). ) (Step 15). Then, the process proceeds to step 16 and returns to step 2 in the same manner as described above.

  If it is determined in step 5 that Ibθ (t2) is larger than Ibθ (t1), the process proceeds to step 15 to output the actual steering angle system current command value Ibθ (t2). In such a case, the steering state is shown as being steered from the neutral steering angle, and thus the steering force is in a direction to increase. In such a situation, if the current command value Ibθ is delayed, an excessive steering force is caused. become. Therefore, as described above, the actual steering angle system current command value Ibθ (t2) is output.

  Further, when it is determined in step 10 that the steering angle system reference decrease rate Δaθ is larger than the actual steering angle system decrease rate Δbθ, the process proceeds to step 15 and the actual steering angle system current command value Ibθ (t2). ) Is output. That is, when the current command value is decreasing but not decreasing so rapidly, the actual steering angle system current command value Ib (t2) is controlled.

  On the other hand, if it is determined in step 8 that the speed is low, the process proceeds to step 17 where the actual steering angle system current command value Ibθ output at that time is maintained at the steering angle system current command value Iaθ. However, the steering angle system current command value Iaθ output at this time corresponds to the actual steering angle system current command value Ibθ. Therefore, when the steering wheel is operated at a low speed, the current command value does not decrease at all.

Next, the delay control of the steering angular velocity system will be described.
In step 0, the steering angular velocity system reference reduction rate Δaω is taken in and stored in the delay control characteristic storage unit. Next, in step 1, the actual steering angular velocity system current command value Ibω (t1) at time t1 is detected, and in step 2, the time t1 and the detected value Ibω (t1) are stored.
In step 3, an actual steering angular velocity system current command value Ibω (t2) at a time t2 after a predetermined time has elapsed is detected. In step 4, the time t2 and the detected value Ibω (t2) are stored.

  In step 5, the steering angular velocity system current command value Ibω (t1) is compared with the steering angular velocity system current command value Ibω (t2). When Ibω (t2) is smaller than Ibω (t1), that is, when it is determined that the current command value has decreased, the routine proceeds to step 6 where the actual steering angular velocity system current command value Ibω per unit time is determined. A steering angular velocity system reduction rate Δbω is calculated.

  In step 7, the vehicle speed is detected, and in step 8, the vehicle speed determination unit determines whether the vehicle speed is low or high. When the vehicle speed determination unit determines that the vehicle speed is high, the process proceeds to step 9 to set the steering angular velocity system reference decrease rate Δaω. When the steering angular velocity system reference reduction rate Δaω is set in this way, in step 10, the steering angular velocity system reference reduction rate Δaω is compared with the actual steering angular velocity system reduction rate Δbω. When it is determined that the steering angular velocity system reference reduction rate Δaω is smaller than the actual steering angular velocity system reduction rate Δbω, the routine proceeds to step 11 and a steering angular velocity system reference current command based on the steering angular velocity system reference reduction rate Δaω. The value Iaω is output.

  When the steering angular velocity system reference current command value Iaω is output in this way, a value larger than the actual steering angular velocity system current command value Ibω is output, as shown by a one-dot chain line in FIG. Therefore, as shown in FIG. 27, since a sudden increase in steering torque can be suppressed, a sense of discomfort given to the driver can be prevented.

  In step 12, the steering angular velocity system reference current command value Iaω is compared with the actual steering angular velocity system current command value Ibω (t2), and the steering angular velocity system reference current command value Iaω is determined as the actual steering angular velocity system current command value Ibω ( If it is greater than t2), the vehicle speed is detected in step 13, and it is determined in step 14 whether the vehicle speed is high or low. Then, when the speed is high, the process returns to the above step 10, and when the steering angular velocity system reduction rate Δaω is smaller than the actual steering angular velocity system reduction rate Δbω, the steering angular velocity system reference current command based on the steering angular velocity system reference reduction rate Δaω. Control will continue with the value Iaω.

  On the other hand, if it is determined at step 14 that the speed is low, the routine proceeds to step 17 where the steering angular velocity system current command value Iaω output at that time is maintained as shown in FIG. If the steering angular velocity system current command value Iaω is maintained in this way, as shown in FIG. 27, the steering torque does not increase any more, so that the uncomfortable feeling caused by the increase in the steering torque can be prevented more reliably.

  In step 18, it is determined whether or not the steering angular velocity system reference current command value Iaω that is maintained constant is larger than the actual steering angular velocity system current command value Ibω. When the steering angular velocity system reference current command value Iaω is larger than the actual steering angular velocity system current command value Ibω (t2), the routine proceeds to step 16, where t2 is replaced with t1, and Ibθ (t2) is replaced with Ibθ (t1). replace. And it returns to step 2 again and repeats the said procedure.

  On the other hand, when the steering angular velocity system current command value Iaω, which is maintained constant in step 18, becomes equal to or less than the actual steering angular velocity system current command value Ibω (t2), the actual steering angular velocity system current command value Ibω (t2). ) (Step 15). Then, the process proceeds to step 16 and returns to step 2 in the same manner as described above.

  If it is determined in step 5 that Ibω (t2) is larger than Ibω (t1), the process proceeds to step 15 to output the actual steering angular velocity system current command value Ibω (t2). In such a case, the steering state is shown as being steered from the neutral steering angle, and thus the steering force is in the direction of increasing. In such a situation, if the current command value Ibω is delayed, an excessive steering force is caused. become. Therefore, as described above, the actual steering angular velocity system current command value Ibω (t2) is output.

  Further, when it is determined in step 10 that the steering angular velocity system reference reduction rate Δaω is larger than the actual steering angular velocity system reduction rate Δbω, the process proceeds to step 15 and the actual steering angular velocity system current command value Ibω (t2 ) Is output. That is, when the current command value is decreasing but not decreasing so rapidly, the actual steering angular velocity system current command value Iω (t2) is controlled.

  On the other hand, if it is determined in step 8 that the speed is low, the process proceeds to step 17 where the actual steering angular velocity system current command value Ibω output at that time is maintained at the steering angular velocity system current command value Iaω. However, the steering angular velocity system current command value Iaω output at this time corresponds to the actual steering angular velocity system current command value Ibω. Therefore, when the steering wheel is operated at a low speed, the current command value does not decrease at all.

  In the sixth embodiment, when the actual current command value Ibθ (Ibω) is decreasing and it is determined that the decrease rate Δbθ (Δbω) is larger than the reference decrease rate Δaθ (Δaω). Only, the reference current command value Iaθ (Iaω) based on the reference decrease rate Δaθ (Δaω) is output. In this way, as shown in FIG. 26, the steering torque required for the driver is gradually reduced as indicated by the two-dot chain line for the steering angle system and as indicated by the one-dot chain line for the steering angular velocity system. Decrease. Therefore, the amount of change in the steering torque can be suppressed to be smaller than that based on the actual current command value Ibθ (Ibω), and a sense of incongruity caused by a sudden change in the steering torque can be prevented.

  In particular, when the vehicle speed is low, the current command value Iaθ (Iaω) is maintained at the actual current command values Ibθ (t2) and Ibω (t2) that are output at that time. While smooth steering is possible, it is possible to give a sharp and neutral feeling when traveling at high speed.

  On the other hand, in the seventh embodiment shown in FIGS. 29 to 33, on / off switching of the current command value maintaining unit in the sixth embodiment is controlled by the steering angular velocity determining unit for the steering angular system, and the steering angular velocity system is controlled. Is controlled by the steering angle determination unit.

  FIG. 33 shows the control of the steering angle system of the seventh embodiment. The procedure from Step 1 to Step 6, the procedure from Step 10 to Step 12, and the procedure of Step 15 and Step 16 are exactly the same as in the sixth embodiment. However, in the seventh embodiment, the steering angular velocity is detected in step 7, and the magnitude of the steering angular velocity is determined in step 8. Similarly to steps 7 and 8, the steering angular velocity is detected also in step 13, and the magnitude of the steering angular velocity is determined in step 14.

  In step 8 and step 14, when it is determined that the steering angular velocity is larger than a predetermined value, the process proceeds to step 17, and the current command value Iaθ output at that time is maintained. When the steering angular velocity is large, the vehicle is often traveling at a low speed. Therefore, in the seventh embodiment, the vehicle speed is predicted based on the steering angular velocity, and the control suitable for the traveling state can be performed as in the sixth embodiment.

  On the other hand, when the steering angular velocity is low, the vehicle is often traveling at a high speed. Therefore, if it is determined in step 8 and step 14 that the steering angular velocity is equal to or less than a predetermined value, the reference decrease is made. When the rate Δaθ is smaller than the actual decrease rate Δbθ, the reference current command value Iaθ is output, and in the opposite case, the actual current command value Ibθ is output.

On the other hand, with respect to the steering angular velocity system, when it is determined in step 8 and step 14 that the steering angle is smaller than a predetermined value, the routine proceeds to step 17, and the steering angular velocity system current command value Iaω output at that time is maintained. To do.
On the other hand, if it is determined in step 8 and step 14 that the steering angle is greater than or equal to a predetermined value, the steering angular velocity system is reduced when the steering angular velocity system reference reduction rate Δaω is smaller than the actual steering angular velocity system reduction rate Δbω. The reference current command value Iaω is output, and in the opposite case, the actual steering angular velocity system current command value Ibω is output.
According to the seventh embodiment thus configured, smooth steering can be achieved, and a sharp and neutral feeling can be provided.

  In the first to seventh embodiments, the coefficient is multiplied to control the reference reduction rate Δaθ (Δaω) variably, but instead of multiplying the coefficient, it is based on a prestored table value. The reference reduction rate Δaθ (Δaω) may be variably controlled.

  In the first to seventh embodiments, the limiters having the current command values I7 and I8 as limit values are individually set immediately after the current command values I5 and I6 are multiplied as gains. However, the limiters are individually set. Instead of setting, a limiter having a current command value corresponding to the vehicle speed as a limit value may be set uniformly to the value after adding the standby current command value.

Further, instead of individually multiplying the current command values I5 and I6 based on the vehicle speed, the value after the magnitude determination may be uniformly multiplied with the current command value based on the vehicle speed as a gain.
Furthermore, a limiter having a current command value corresponding to the vehicle speed as a limit value may be uniformly set to the value after adding the standby current command value, or the value after the magnitude determination is based on the vehicle speed. The current command value may be uniformly multiplied as a gain.

  In the first to seventh embodiments, the opening of the variable orifice a of the flow control valve V is controlled by the controller C so that the control flow QP is not wasted. This is controlled by adjusting the opening degree of the tank port 11 as shown in FIG. That is, the control flow rate QP is controlled by circulating an unnecessary flow rate of the oil discharged from the pump P to the tank T via the tank port 11. The flow path for guiding the oil discharged from the pump P to the tank port 11 is very short because it is inside the main body B.

  Accordingly, there is almost no pressure loss in the circulating flow path, and therefore the oil temperature hardly increases. That is, in the first to seventh embodiments, the flow rate control valve V is configured to circulate a flow rate other than the control flow rate QP to the tank T via the tank port 11, so that the increase in the oil temperature is suppressed. An effect can also be obtained.

It is a control block diagram of the controller C of 1st Embodiment. It is explanatory drawing which shows the relationship between a steering angle and time. It is explanatory drawing which shows the relationship between an electric current command value and time. It is explanatory drawing which shows the relationship between the required steering torque and time. It is a control flowchart of the controller C of 1st Embodiment. It is a control block diagram of the controller C of 2nd Embodiment. It is explanatory drawing which shows the relationship between a steering angle and time. It is explanatory drawing which shows the relationship between an electric current command value and time. It is explanatory drawing which shows the relationship between the required steering torque and time. It is a control flow figure of controller C of a 2nd embodiment. It is a control block diagram of the controller C of 3rd Embodiment. It is explanatory drawing which shows the relationship between a steering angle and time. It is explanatory drawing which shows the relationship between an electric current command value and time. It is explanatory drawing which shows the relationship between the required steering torque and time. It is a control flow figure of controller C of a 3rd embodiment. It is a control block diagram of the controller C of 4th Embodiment. It is explanatory drawing which shows the relationship between a steering angle and time. It is explanatory drawing which shows the relationship between an electric current command value and time. It is explanatory drawing which shows the relationship between the required steering torque and time. It is a control block diagram of controller C of a 5th embodiment. It is explanatory drawing which shows the relationship between a steering angle and time. It is explanatory drawing which shows the relationship between an electric current command value and time. It is explanatory drawing which shows the relationship between the required steering torque and time. It is a control block diagram of controller C of a 6th embodiment. It is explanatory drawing which shows the relationship between a steering angle and time. It is explanatory drawing which shows the relationship between an electric current command value and time. It is explanatory drawing which shows the relationship between the required steering torque and time. It is a control flow figure of controller C of a 6th embodiment. It is a control block diagram of controller C of a 7th embodiment. It is explanatory drawing which shows the relationship between a steering angle and time. It is explanatory drawing which shows the relationship between an electric current command value and time. It is explanatory drawing which shows the relationship between the required steering torque and time. It is a control flow figure of controller C of a 7th embodiment. It is a general view of the conventional apparatus. It is a control block diagram of a conventional controller C. It is the graph which showed the change of the current command value at the time of the conventional steering.

Explanation of symbols

V Flow control valve P Pump SOL Solenoid T Tank a Variable orifice 8 Power cylinder 9 Steering valve C Controller 14 Steering angle sensor 15 Vehicle speed sensor SI Solenoid current command value Is Current command value for standby

Claims (5)

  A steering valve for controlling the power cylinder; a variable orifice provided upstream of the steering valve; a solenoid for controlling the opening of the variable orifice; a controller for controlling a solenoid current command value SI for driving the solenoid; A steering situation detection sensor that detects a steering situation such as a steering angle and a steering angular velocity and is connected to the controller, and pressure oil supplied from the pump is supplied to the steering valve side and the tank or pump side according to the opening of the variable orifice. In a power steering apparatus in which the controller specifies a solenoid current command value based on current command values corresponding to various signals from the steering situation detection sensor, the controller A command value characteristic storage unit, a delay control characteristic storage unit, The current command value characteristic storage unit stores an actual steering angle system current command value Ibθ and a steering angular velocity system current command value Ibω based on the steering angle signal and the steering angular velocity signal from the steering situation detection sensor. The delay control characteristic storage unit stores a steering angle system reference reduction rate Δaθ and a steering angular velocity system reference reduction rate Δaω that specify the steering angle system reference current command value Iaθ and the steering angular velocity system reference current command value Iaω, and executes The steering angle system current command value Ibθ and the steering angular velocity system current command value Ibω respectively calculate the steering angle system decrease rate Δbθ and the steering angular velocity system decrease rate Δbω per unit time, and the calculated decrease rates Δbθ and Δbω, respectively. The magnitudes of the reference reduction rates Δaθ and Δaω are respectively compared. When Δaθ ≧ Δbθ and Δaω ≧ Δbω, the actual steering angle system current command value Ibθ and the steering angular velocity system current index are compared. The command value Ibω is output, respectively, and when Δaθ <Δbθ and Δaω <Δbω, the steering angle system reference current command value Iaθ and the steering angular velocity system reference current command value Iaω based on the reference decrease rates Δaθ and Δaω are specified, and A power steering apparatus characterized by selecting and outputting the larger one of the specified steering angle system value and steering angular velocity system value.   The steering angle system reference decrease rate Δaθ and the steering angular velocity system reference decrease rate Δaω keep the minimum value when the vehicle speed is in the low speed range, increase as the vehicle speed increases in the medium speed range, and reach the maximum value in the high speed range. The power steering apparatus according to claim 1, wherein the power steering apparatus is maintained.   The steering angle reference reduction rate Δaθ maintains the highest value when the steering angular velocity is in the small region, decreases with the increase of the steering angular velocity in the middle region, and maintains the minimum value in the large region, while the steering angular velocity system reference 2. The power according to claim 1, wherein the reduction rate Δaω is kept at a minimum value when the vehicle speed is in a low speed range, increases with an increase in the vehicle speed at a medium speed range, and keeps a maximum value at a high speed range. Steering device.   The steering angle system reference decrease rate Δaθ keeps the minimum value when the vehicle speed is in the low speed range, increases as the vehicle speed increases in the medium speed range, and keeps the maximum value in the high speed range, while decreasing the steering angular speed system reference decrease The rate Δaω is maintained at a minimum value when the steering angle is in a small region, increases with an increase in the steering angle when in a middle region, and maintains a maximum value in a large region. Power steering device.   The steering angle reference reduction rate Δaθ maintains the highest value when the steering angular velocity is in the small region, decreases with the increase of the steering angular velocity in the middle region, and maintains the minimum value in the large region, while the steering angular velocity system reference 2. The reduction rate Δaω maintains a minimum value when the steering angle is in a small region, increases with an increase in the steering angle when the steering angle is in a middle region, and maintains a maximum value in a large region. Power steering device.

Images