JP4619191B2 - Power steering device - Google Patents

Description

  The present invention relates to a power steering apparatus provided with a flow rate control valve for controlling a flow rate guided to a power cylinder side.

As this type of device, one described in Patent Document 1 has been conventionally known, and FIGS. 2 and 3 show this conventional device. First, the configuration of the entire power steering apparatus will be described with reference to FIG.
A pump P is integrally incorporated in the main body B together with the spool 1 of the flow control valve V.
The spool 1 has one end facing one pilot chamber 2 and the other end facing the other pilot chamber 3. The one pilot chamber 2 is always in communication with the pump P through the pump port 4. A spring 5 is interposed in the other pilot chamber 3. The pilot chambers 2 and 3 thus configured communicate with each other via a variable orifice a that controls the opening degree according to the excitation current I of the solenoid SOL.

That is, 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. The other pilot chamber 3 communicates with the inflow side of the steering valve 9 via the flow path 10 and the flow path 7.
Therefore, both the pilot chambers 2 and 3 communicate with each other via the variable orifice a, and the pressure on the upstream side of the variable orifice a acts on one pilot chamber, and the pressure on the downstream side acts on the other pilot chamber 3. Will act.

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 are balanced. At the balanced position, the opening degree between the pump port 4 and the tank port 11 is maintained. Is decided.
Now, if the pump drive source 12 which consists of an engine etc. has stopped, pressure oil will not be supplied to the pump port 4. FIG. If no pressure oil is supplied to the pump port 4, no pressure is generated in the pilot chambers 2 and 3, so that the spool 1 maintains the illustrated normal position by the action of the spring 5.

When the pump P is driven from the above state and pressure oil is supplied to the pump port 4, a flow can be made to the variable orifice a, so that a pressure loss occurs there. Due to this pressure loss, a pressure difference is generated between the pilot chambers 2 and 3, and the spool 1 moves against the spring 5 according to the pressure difference and maintains the balance position.
As the spool 1 moves against the spring 5 in this way, the opening degree of the tank port 11 is increased, but the control flow rate guided to the steering valve 9 side according to the opening degree of the tank port 11 at this time A distribution ratio between QP and 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.

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

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 excitation current of the solenoid SOL.
This is because the opening of the variable orifice a is kept to a minimum when the solenoid SOL is in a non-excited state, and the opening is increased as the exciting current is increased.

  The steering valve 9 controls the supply flow rate 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 supply amount to the power cylinder 8 is increased, and if the steering torque is small, the supply flow rate is decreased accordingly. The switching amount of the steering torque and the steering valve 9 is determined by a torsional reaction force such as a torsion bar (not shown).

If the switching amount of the steering valve 9 is increased when the steering torque is large as described above, the assist force by the power cylinder 8 is increased accordingly. On the contrary, if the switching amount of the steering valve 9 is reduced, the assist force is reduced.
If the required (required) flow rate QM of the power cylinder 8 determined by the steering torque and the control flow rate QP determined by the flow control valve V are always equal, 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.

In order to make the control flow rate QP as close as possible to the required flow rate QM of the power cylinder 8 as described above, it is the excitation current for the solenoid SOL that controls the opening of the variable orifice a, and this excitation current is controlled. , Controller C.
A steering angle sensor 16 and a vehicle speed sensor 17 are connected to the controller C, and the excitation current of the solenoid SOL is controlled based on the output signals of both sensors.

In the figure, reference numeral 18 is a slit formed at the tip of the spool 1, and even when the spool 1 is at the position shown in the figure, one pilot chamber 2 always communicates with the flow path 7 via this slit 18. I am doing so. In other words, even when the spool 1 is in the illustrated state and the flow path 6 is closed, the oil discharged from the pump P is supplied to the steering valve 9 side through the slit 18. ing.
Although the flow rate is very small as described above, the pressure oil is supplied to the steering valve 9 side for the purpose of preventing seizure of the entire apparatus, preventing disturbance such as kickback, and ensuring responsiveness. Because. However, these objects can also be achieved by securing a standby flow rate, which will be described later, and a detailed description will be given later.

  Reference numeral 19 denotes a driver connected between the controller C and the solenoid SOL.

  The control system of the controller C is as shown in FIG. In other words, the steering angle signal from the steering angle sensor 16 and the vehicle speed signal from the vehicle speed sensor 17 are input to the controller C. Then, the controller C calculates the steering angle θ and the steering angular velocity ω from the steering angle signal. The required flow rate QM is estimated based on the steering angle θ and the steering angular velocity ω.

  The steering angle θ and the solenoid current command value I1 in FIG. 3 are determined based on theoretical values in which the relationship between the steering angle θ and the control flow rate QP is linear. Further, the relationship between the steering angular velocity ω and the solenoid current command value I2 is also determined based on a theoretical value in which the steering angular velocity ω and the control flow rate QP are linear characteristics.

However, if the steering angle θ and the steering angular velocity ω do not become a certain set value or more, both the command values I1 and I2 are output as zero. That is, when the steering wheel is neutral or in the vicinity thereof, the command values I1 and I2 are set to zero.
The solenoid current command value I1 for the steering angle θ and the solenoid current command value I2 for the steering angular velocity ω are stored in advance in the controller C as table values.

  The controller C outputs the steering angle current command value I3 and the steering angular velocity current command value I4 based on the output signal of the vehicle speed sensor 17, and the steering angle current command value I3 and The steering angular velocity current command value I4 is stored in advance in the controller C as a table value.

The steering angle current command value I3 is set to 1 in the low speed range and, 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 to, for example, 0.8 in the maximum speed range.
That is, the steering angle current command value I3 is controlled in the range of 1 to 0.6, while the steering angular speed current command value I4 is controlled in the range of 1 to 0.8. Therefore, the gain from the low speed range to the maximum speed range is greater for the steering angle current command value I3.

  The solenoid current command value I1 based on the steering angle θ is multiplied by the steering angle current command value I3 corresponding to the vehicle speed signal V. Therefore, the higher the vehicle speed signal V, the smaller the output value that is the multiplication result, that is, the steering angle system current command value I5. In addition, since the gain of the steering angle current command value I3 is larger than the gain of the steering angular velocity current command value I4, the reduction rate increases as the speed increases.

  On the other hand, for the solenoid current command value I2 based on the steering angular velocity ω, the steering angular velocity system current command value I6 is output with the steering angular velocity current command value I4 corresponding to the vehicle speed as a limit value. The steering angular velocity system current command value I6 is also decreased in accordance with the vehicle speed, but since the gain is smaller than the gain of the steering angular current command value I3, the steering angular velocity system current command value I6. The rate of decrease is smaller than that of the steering angle system current command value I5.

The steering angle system current command value I5 output as described above is compared with the steering angular velocity system current command value I6, and the large current command value I5 or I6 is adopted.
The reason for adopting the larger one in this way is as follows. In other words, since the steering is rarely operated suddenly at high speed, the steering angular velocity system current command value I6 is usually small and the steering angular system current command value I5 is large when the steering operation is performed. is there.

  Therefore, when traveling at high speed, the larger steering angle system current command value I5 is adopted while using the steering angle as a reference to improve the safety and stability of the steering operation. Moreover, by doing in this way, the higher the traveling speed, the higher the ratio of decreasing the control flow rate QP, and the more energy loss can be achieved.

On the other hand, when the vehicle is traveling at a low speed, the steering is frequently operated rapidly. Therefore, in many cases, the steering angular velocity is larger. Thus, when the steering angular velocity is large, responsiveness is important.
Therefore, when traveling at a low speed, the steering angular velocity system current command value I6 is adopted while using the steering angular velocity as a reference to improve the operability of the steering operation, that is, the responsiveness. In this way, even when the traveling speed is increased to some extent, when the steering is suddenly operated, the control flow rate QP can be sufficiently secured and priority can be given to responsiveness.

Even if the vehicle traveling speed is constant, the steering angular system current command value I5 may increase or the steering angular speed system current command value I6 may increase. For example, when the steering is steered at a certain angle and the steering is held at the position of the steering angle θ, the steering angular velocity ω becomes zero. In this case, although the vehicle speed is the same, the steering angular velocity system current command value I6 is initially large, and the steering angular system current command value I5 becomes larger after the steering is maintained.
However, in this apparatus, since the larger one of the current command values I5 and I6 is selected, any current command value is output under any traveling condition.

  If neither of the current command values I5 and I6 is output at the time of steering as described above, the control flow rate QP cannot be secured. If the control flow rate QP cannot be secured, the power cylinder 8 will move at the time of steering while losing the drag due to the self-aligning torque of the vehicle. If the power cylinder 8 moves without maintaining its position in this way, it is impossible to maintain the steering itself.

  However, as described above, since either one of the current command values I5 and I6 is used, neither of them becomes zero during the steering operation. In other words, since the steering angle θ is maintained even during steering, the solenoid current command value I1 can be secured. Therefore, the power required for steering can be maintained at the current command value I1.

  On the other hand, the steering may be suddenly operated even when traveling at high speed. At this time, since the steering angular velocity system current command value I6 increases, the steering angular velocity system current command value I6 is selected. However, since the steering angular velocity system current command value I6 becomes a value controlled within the limit value range of the steering angular velocity current command value I4, safety is sufficiently ensured.

Further, the standby current command value I7 is added to the current command value I5 or I6 selected as described above.
The standby current command I7 is for always supplying a predetermined current to the solenoid SOL of the variable orifice a. Thus, the variable orifice a supplied with the standby current command value I7 has a constant opening degree even if the solenoid current command value based on the steering angle θ, the steering angular velocity ω, and the vehicle speed is zero. While maintaining a constant standby flow rate.

Next, the operation of the conventional apparatus will be described.
When 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 solenoid current command value I2 based on the steering angular velocity is output as the steering angular velocity system current command value I6 with the steering angular velocity current command value I4 as the limit value.

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

However, even during low-speed running, the solenoid excitation current I is determined based on the steering angle system current command value I5 during steering.
Even when the vehicle is traveling at high speed, when the steering is suddenly operated, the excitation current I of the solenoid is determined based on the steering angular velocity system current command value I6.
JP 2001-260917 A

  The conventional device as described above controls the current command value according to the vehicle speed, but the vehicle speed sensor only detects the rotational speed of the wheel, and the controller determines the rotational speed of the wheel. The vehicle speed is calculated.

  Therefore, for example, if the wheel spins at a sudden start, the vehicle speed calculated by the controller increases according to the rotation speed. In other words, only the apparent vehicle speed increases even though the actual vehicle speed is low at a low speed.

  On the contrary, when a sudden brake is applied such that the wheels are locked, the vehicle speed calculated by the controller in accordance with the number of rotations is lowered. In other words, only the apparent vehicle speed is lowered although the actual vehicle speed is almost not decreased.

  Since the controller calculates the solenoid current command value based on the apparent vehicle speed, for example, at the time of sudden start as described above, there is some power shortage in the device. For this reason, the driver may feel uncomfortable that the steering wheel is caught for a moment. On the other hand, at the time of sudden braking as described above, the power of the device is slightly overrun. For this reason, the driver may feel uncomfortable as if the steering wheel is missing for a moment.

As a result, the above-described conventional apparatus has a problem that the driver feels uncomfortable when suddenly starting or braking.
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 suddenly starting and braking.

  The present invention assumes the following configuration. That is, a spool is incorporated in the main body, one end of the spool faces one pilot chamber that is always in communication with the pump port, and the other end of the spool faces the other pilot chamber with a spring interposed therebetween. An orifice is provided on the downstream side of the pilot chamber, and pressure oil is guided to the steering valve that controls the power cylinder through the orifice, while the pressure upstream of the orifice is used as the pilot pressure of the one pilot chamber, The pressure is set as the pilot pressure of the other pilot chamber, and the movement position of the spool is controlled by the pressure balance of both pilot chambers, and the control flow rate QP for guiding the pump discharge amount to the steering valve side according to the movement position, And the return flow rate QT to be recirculated to the tank or pump, Is a variable orifice that controls the opening according to the excitation current I of the solenoid, and a controller that controls the excitation current I of the solenoid of this variable orifice is provided, and a steering angle sensor is connected to this controller. The controller calculates or stores the steering angle θ and the steering angular velocity ω corresponding to the steering angle from the steering angle sensor, while the controller outputs a solenoid current command value I1 corresponding to the steering angle θ and a solenoid corresponding to the steering angular velocity ω. The current command value I2 is stored or calculated, and the excitation current I of the solenoid of the variable orifice is controlled based on these current command values I1 and I2.

The first invention presupposes the above-described device, and the arithmetic unit provided in the controller switches the switch to the normal control system, the special control system, or the return control system according to the output signal, and at regular intervals. A vehicle speed detection function for detecting the vehicle speed, a vehicle speed change calculation function for calculating the vehicle speed change amount ΔV per unit time, and a change in which the vehicle speed V0 calculated immediately before and the current vehicle speed change amount | ΔV | A function that determines whether the amount exceeds ΔVf, and when the change amount | ΔV | ≦ the set change amount ΔVf, it is determined that the vehicle is in normal operation without sudden start or sudden braking, and the switch is switched to the normal control system Te, a function of outputting a current command value based on the current instruction value I1 or I2 as a solenoid excitation current I, when the change amount ￨DerutaV￨> vARIATION amount Delta] Vf, Kyuhatsu Or determines that there is a sudden braking, switching the switch to the special control system, the current command value at the time of the sudden acceleration or sudden braking, the function of changing gradually the special current command value in a control time set in advance, When the change amount | ΔV | changes within the set change amount smaller than the set change amount ΔVf in the state of switching to the special control system, the switch is switched to the return control system and the current command value I1 or It is characterized in that it has a function of returning to a current command value based on I2.

According to a second aspect of the present invention, the arithmetic unit has a function of storing in advance a delay time for reaching the special control system current command value and causing the special control system current command value to be reached within the delay time. According to a third aspect of the present invention, the arithmetic unit has a function of previously storing a delay time for reaching the return control system current command value and allowing the return control system current command value to be reached within the delay time. It has the characteristics in the point.

  According to the first to third aspects of the invention, the driver does not feel uncomfortable in steering operation even during sudden start and sudden braking.

  FIG. 1 shows an embodiment of the present invention. In this embodiment, the overall structure is exactly the same as that of the conventional apparatus shown in FIG. Therefore, the detailed description regarding the whole structure shown in FIG. 2 is omitted, and in the following description, the description regarding FIG. 2 and the reference numerals used for the description are all incorporated. The feature of this embodiment is that a switch SW for switching is provided immediately after the steering angle system current command value 15 or the steering angular speed system current command value I6 is specified. Alternatively, the control system is switched during sudden change traveling such as sudden braking. However, in the following, each component of FIG.

  The control system of the controller C in this embodiment is as shown in FIG. In other words, the steering angle signal from the steering angle sensor 16 and the vehicle speed signal from the vehicle speed sensor 17 are input to the controller C. Then, the controller C calculates the steering angle θ and the steering angular velocity ω from the steering angle signal. The required flow rate QM is estimated based on the steering angle θ and the steering angular velocity ω.

  The steering angle θ and the solenoid current command value I1 in FIG. 1 are determined based on a theoretical value at which the relationship between the steering angle θ and the control flow rate QP is linear. Further, the relationship between the steering angular velocity ω and the solenoid current command value I2 is also determined based on a theoretical value in which the steering angular velocity ω and the control flow rate QP are linear characteristics.

However, if the steering angle θ and the steering angular velocity ω do not become a certain set value or more, both the command values I1 and I2 are output as zero. That is, when the steering wheel is neutral or in the vicinity thereof, the command values I1 and I2 are set to zero.
The solenoid current command value I1 for the steering angle θ and the solenoid current command value I2 for the steering angular velocity ω are stored in advance in the controller C as table values. However, in the present invention, the controller C may calculate the current command values I1 and I2 each time.

  The controller C outputs the steering angle current command value I3 and the steering angular velocity current command value I4 based on the output signal of the vehicle speed sensor 17, and the steering angle current command value I3 and The steering angular velocity current command value I4 is stored in advance in the controller C as a table value.

The steering angle current command value I3 is set to 1 in the low speed range and, 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 to, for example, 0.8 in the maximum speed range.
That is, the steering angle current command value I3 is controlled in the range of 1 to 0.6, while the steering angular speed current command value I4 is controlled in the range of 1 to 0.8. Therefore, the gain from the low speed range to the maximum speed range is set to be larger for the steering angle current command value I3.

  The solenoid current command value I1 based on the steering angle θ is multiplied by the steering angle current command value I3 corresponding to the vehicle speed signal V. Therefore, the higher the vehicle speed signal V, the smaller the output value that is the multiplication result, that is, the steering angle system current command value I5. In addition, since the gain of the steering angle current command value I3 is larger than the gain of the steering angular velocity current command value I4, the reduction rate increases as the speed increases.

  On the other hand, for the solenoid current command value I2 based on the steering angular velocity ω, the steering angular velocity system current command value I6 is output with the steering angular velocity current command value I4 corresponding to the vehicle speed as a limit value. The steering angular velocity system current command value I6 is also decreased according to the vehicle speed, but the gain is made smaller than the gain of the steering angular current command value I3. The rate of decrease is smaller than that of the steering angle system current command value I5.

The steering angle system current command value I5 output as described above is compared with the steering angular velocity system current command value I6, and the large current command value I5 or I6 is adopted.
The reason for adopting the larger one in this way is as follows. In other words, since the steering is rarely operated suddenly at high speed, the steering angular velocity system current command value I6 is usually small and the steering angular system current command value I5 is large when the steering operation is performed. is there.

  Therefore, when traveling at high speed, the larger steering angle system current command value I5 is adopted while using the steering angle as a reference to improve the safety and stability of the steering operation. Moreover, by doing in this way, the higher the traveling speed, the higher the ratio of decreasing the control flow rate QP, and the more energy loss can be achieved.

On the other hand, when the vehicle is traveling at a low speed, the steering is frequently operated rapidly. Therefore, in many cases, the steering angular velocity is larger. Thus, when the steering angular velocity is large, responsiveness is important.
Therefore, when traveling at a low speed, the steering angular velocity system current command value I6 is adopted while using the steering angular velocity as a reference to improve the operability of the steering operation, that is, the responsiveness. In this way, even when the traveling speed is increased to some extent, when the steering is suddenly operated, the control flow rate QP can be sufficiently secured and priority can be given to responsiveness.

Even if the vehicle traveling speed is constant, the steering angular system current command value I5 may increase or the steering angular speed system current command value I6 may increase. For example, when the steering is steered at a certain angle and the steering is held at the position of the steering angle θ, the steering angular velocity ω becomes zero. In this case, although the vehicle speed is the same, the steering angular velocity system current command value I6 is initially large, and the steering angular system current command value I5 becomes larger after the steering is maintained.
However, in this apparatus, since the larger one of the current command values I5 and I6 is selected, any current command value is output under any traveling condition.

  If neither of the current command values I5 and I6 is output at the time of steering as described above, the control flow rate QP cannot be secured. If the control flow rate QP cannot be secured, the power cylinder 8 will move at the time of steering while losing the drag due to the self-aligning torque of the vehicle. If the power cylinder 8 moves without maintaining its position in this way, it is impossible to maintain the steering itself.

  However, as described above, since either one of the current command values I5 and I6 is used, neither of them becomes zero during the steering operation. In other words, since the steering angle θ is maintained even during steering, the solenoid current command value I1 can be secured. Therefore, the power required for steering can be maintained at the current command value I1.

  On the other hand, the steering may be suddenly operated even when traveling at high speed. At this time, since the steering angular velocity system current command value I6 increases, the steering angular velocity system current command value I6 is selected. However, since the steering angular velocity system current command value I6 becomes a value controlled within the limit value range of the steering angular velocity current command value I4, safety is sufficiently ensured.

Further, the standby current command value I7 is added to the current command value I5 or I6 selected as described above.
The standby current command I7 is for always supplying a predetermined current to the solenoid SOL of the variable orifice a. Thus, the variable orifice a supplied with the standby current command value I7 has a constant opening degree even if the solenoid current command value based on the steering angle θ, the steering angular velocity ω, and the vehicle speed is zero. While maintaining a constant standby flow rate.

  The vehicle speed sensor 17 detects the number of rotations of the wheel as in the conventional case, but always inputs the detection result to the calculation unit E in the controller C. The calculation unit E controls the above-described switch SW. As is clear from FIG. 1, the switch SW can be switched to a normal control system, a special control system, and a return control system, and the above calculation is performed. Part E selectively controls these three control systems.

  And the said calculating part E calculates a vehicle speed based on the rotation speed of the wheel input from the vehicle speed sensor 17, but repeats the calculation for every decided time. The calculation unit E compares the vehicle speed signal V, which is the calculation result, with the immediately preceding vehicle speed signal V0, and determines the magnitude of the change amount | ΔV | and a preset change amount ΔVf.

  The set change amount ΔVf is stored in advance in the calculation unit E. In this embodiment, the set change amount ΔVf is set to, for example, (20 km / h) / s. This set change amount ΔVf (20 km / h) / s means a gain for specifying the change amount of the vehicle speed per unit time.

  Then, if the magnitude of the change amount | ΔV | as the calculation result and the set change amount ΔVf is determined as | ΔV | ≦ ΔVf, the calculation unit E does not cause a sudden start or a sudden brake or the like. Determine normal operation. In this way, when the calculation unit E determines that the operation is normal, the switch SW is maintained in the illustrated normal control system. When the normal control system is selected in this way, the standby current command value I7 is added to either the steering angle system current command value I5 or the steering angular velocity system current command value I6 after the magnitude determination as described above. The solenoid excitation current I which is the value obtained is output.

  On the other hand, if the calculation unit E determines that | ΔV |> ΔVf, it is determined that there is a sudden start or a sudden brake. When it is determined that there has been a sudden start or a sudden brake, the switch SW is switched to the special control system by the calculation unit E. Thus, when the switch SW is switched to the special control system, the controller C is required to ensure that the current command value at the time of sudden start or at the time of sudden braking is, for example, a maximum flow rate within a preset control time. Control is performed so as to reach a special control system current command value I8 that is ½ of the current command value. The reason why the control time is set in advance and gradually changed to the special current command value I8 is that the driver may feel uncomfortable if the current command value is changed suddenly during sudden start or sudden braking. This is to prevent this from happening.

  In the state where the switch SW is switched to the special control system as described above, the calculation unit E determines that the change amount | ΔV | which is the difference between the current vehicle speed signal V and the immediately preceding vehicle speed signal V0 is the return control. A comparison is made as to whether or not the reference set value is, for example, (5 km / h) / s or less. When the amount of change | ΔV | becomes equal to or less than the set value (5 km / h) / s, the calculation unit E switches the switch SW to the return control system.

  When the switch SW is switched to the return control system as described above, the controller C causes the current command value at the time of sudden start or sudden braking to return to the current command value in the normal control system within a preset control time. To control. The reason for setting the control time in advance and gradually returning it to the current command value of the normal control system is that if the current command value is changed too suddenly, the driver may feel uncomfortable. This is to prevent anything from happening.

Next, the operation of the above embodiment will be described.
Now, during traveling of the vehicle, the calculation unit E calculates the vehicle speed based on the number of rotations of the wheels input from the vehicle speed sensor 17. Further, the calculation unit E compares the vehicle speed signal V, which is the calculation result, with the immediately preceding vehicle speed signal V0, and determines the magnitude of the change amount | ΔV | and a preset change amount ΔVf.

  If the calculation unit E determines that the change amount | ΔV |, which is the calculation result, and the set change amount ΔVf are | ΔV | ≦ ΔVf, there is no sudden start or sudden braking or the like. It is determined that the operation is normal, and the switch SW is maintained in the illustrated normal control system. Therefore, the solenoid excitation current I is determined based on the current command value obtained by adding the standby current command value I7 to the steering angle system current command value I5 or the steering angular velocity system current command value I6.

  On the other hand, if the calculation unit E determines that | ΔV |> ΔVf, it is determined that a sudden start or a sudden brake or the like has occurred, and the switch SW is switched from the illustrated normal control system to the special control system. If the switch SW is switched to the special control system as described above, the controller C outputs a special control system current command value of a system different from the normal control system. That is, the current command value at the time of sudden start or sudden braking gradually becomes a special control system current command value I8 that is ½ of the current command value required to ensure the maximum flow rate within a preset control time. Control to reach.

  In the state where the switch SW is switched to the special control system as described above, the calculation unit E determines that the change amount | ΔV | which is the difference between the current vehicle speed signal V and the immediately preceding vehicle speed signal V0 is the return control. It is compared whether it became below the standard set value (5km / h) / s. When the amount of change | ΔV | becomes equal to or less than the set value of 5 km / h / s, the calculation unit E switches the switch SW to the return control system. Thus, when the switch SW is switched to the return control system, the controller C gradually returns the current command value at the time of sudden start or sudden braking to the current command value in the normal control system within a preset control time. To control.

  In the embodiment described above, the driver does not feel uncomfortable at the time of sudden start or sudden braking even though the controller calculates the solenoid current command value based on the apparent vehicle speed.

  It should be noted that the flow rate determined by the special control system described in the above embodiment is 1 / 2Qmax, the vehicle speed setting change amount ΔVf that is a judgment criterion for sudden change in vehicle speed, the setting change amount that is a judgment reference for sudden change in vehicle speed, and the control system is Each control time to be changed to the set flow rate when switching is merely an example, and is appropriately adjusted to an optimum value by tuning.

It is explanatory drawing which shows the control system of the controller which shows embodiment of this invention. It is explanatory drawing which shows the control system of the controller of the conventional power steering apparatus. It is explanatory drawing which shows the whole structure of the conventional power steering apparatus.

Explanation of symbols

I Solenoid current command value I1 Solenoid current command value by steering angle θ I2 Solenoid current command value by steering angular velocity ω I3 Steering angle current command value I4 Steering angular velocity current command value I5 Steering angle system current command value I6 Steering angular velocity system current command Value QP Control flow rate QT Return flow rate QM Required flow rate (required flow rate)
QS standby flow rate B body 1 spool 2 one pilot chamber 3 other pilot chamber 4 pump port P pump SOL solenoid a variable orifice 8 power cylinder 9 steering valve C controller 16 steering angle sensor 17 vehicle speed sensor T tank

Claims (3)

A spool is incorporated in the main body, one end of this spool faces one pilot chamber that is always in communication with the pump port, and the other end of the spool faces the other pilot chamber with a spring interposed therebetween. An orifice is provided on the downstream side of the cylinder, and pressure oil is guided to the steering valve that controls the power cylinder through the orifice, while the pressure on the upstream side of the orifice is used as the pilot pressure of the one pilot chamber, and the pressure on the downstream side is set. The control position of the spool is controlled by the pilot pressure of the other pilot chamber, and the movement position of the spool is controlled by the pressure balance between the two pilot chambers, and the pump discharge amount to the steering valve side according to the movement position and the tank Alternatively, the flow rate is distributed to the return flow rate QT to be returned to the pump, and the orifice is A variable orifice that controls the opening degree according to the exciting current I of the noid is provided, and a controller that controls the exciting current I of the solenoid of the variable orifice is provided, and a steering angle sensor is connected to the controller, and the steering While calculating or storing the steering angle θ and the steering angular velocity ω according to the steering angle from the angle sensor, the controller calculates the solenoid current command value I1 according to the steering angle θ and the solenoid current command value according to the steering angular velocity ω. In the power steering apparatus configured to store or calculate I2 and control the excitation current I of the solenoid of the variable orifice on the basis of these current command values I1 and I2, the calculation unit provided in the controller uses the output signal to While switching the switch to normal control system, special control system or return control system, The vehicle speed detection function for detecting the vehicle speed at regular time intervals, the vehicle speed change calculation function for calculating the vehicle speed change amount ΔV per unit time, and the change amount | ΔV | between the vehicle speed V0 calculated immediately before and the current vehicle speed A function that determines whether or not the amount of change ΔVf exceeds the preset value, and when the amount of change | ΔV | ≦ the set amount of change ΔVf, it is determined that there is no sudden start or sudden braking, and the switch is When the control system is switched and the current command value based on the current command value I1 or I2 is output as the solenoid excitation current I and when the change amount | ΔV |> the set change amount ΔVf, there is a sudden start or a sudden brake. determines that switching the switch to the special control system, the current command value at the time of the sudden acceleration or sudden braking, gradually special current finger within the control time set in advance Switching a function of changing the value in the cut unusual state in the special control system, the amount of change │ΔV│ is, when the change within set change amount smaller than the set variation Delta] Vf, the control system returns the switch And a function of returning to the current command value based on the current command value I1 or I2.   2. The power steering apparatus according to claim 1, wherein the arithmetic unit has a function of storing in advance a delay time for reaching the special control system current command value and causing the special control system current command value to be reached within the delay time. .   3. The power according to claim 1, wherein the calculation unit has a function of storing in advance a delay time for reaching the return control system current command value and causing the return control system current command value to be reached within the delay time. Steering device.

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