JPH10250613A - Power steering pump control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the rate of fuel consumption by judging the energy saving operating region properly without bringing about the cost-up even at the time of ultra-low speed operation or at a standstill, and widening the energy saving operating region. SOLUTION: A power steering pump control device 10 is to reduce the rate of discharge flow of a hydraulic pump 12 which is driven by an engine, etc., when a vehicle is out of steering, wherein the arrangement includes a vehicle speed sensing means 41 to sense the speed Vel of the vehicle, a steering angle sensing means 42 to sense the steering angle θh of the vehicle, a steer hold condition judging means 25 to judge the steer hold condition (HFLG=0) from the signal θh given by the steering angle sensing means, and a controlling means 25 which passes judgment that the vehicle speed Vel is below the specified value from the signal given by the vehicle speed sensing means and that it is in the steer hold condition (HFLG=0) from the signal θh given by the steer hold condition judging means and suppresses the rate of discharge flow of the hydraulic pump when such judgement is passed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering pump control device used in a power steering device of a vehicle, and more particularly, to a discharge amount of oil supplied from the pump to the power steering device according to an operation state. The present invention relates to a power steering pump control device for increasing and decreasing.

[0002]

2. Description of the Related Art A power steering apparatus supplies pressure oil from a power steering pump to a steering gear box and a power piston as a hydraulic actuator during steering to generate steering assist, that is, a steering assist force. The power steering pump used here basically increases or decreases the discharge amount in conjunction with the engine rotation, while the hydraulic actuator often cuts the steering angle to a large value at low speeds. I need.

For this reason, the hydraulic circuit of the power steering device is provided with a flow control means. By the function of the flow control means, when the power steering pump is in a low rotation range, a relatively large amount of hydraulic oil is supplied to the steering gear box and the steering gear box. Supplied to the hydraulic actuator side, when it is in the middle rotation range, the amount of pressure oil supplied to the hydraulic actuator side is suppressed, the amount of direct return to the pump is increased, and when it reaches the high rotation range, the pressure oil to the hydraulic actuator side is The supply amount is further suppressed to be kept at a substantially constant value, and the amount of direct return to the pump is kept at a maximum.

As described above, the flow rate control means makes it possible to supply a relatively large amount of pressure oil to the hydraulic actuator in the low rotation range, and to supply wasteful hydraulic oil to the hydraulic actuator in the high rotation range. To save energy. Further, this power steering device is required to have a characteristic that the steering assist force is increased during low-speed running and the steering stability is ensured during high-speed running. For this reason, some power control devices of the power steering device are configured to be of a vehicle speed sensitive type. In this case, the supply amount of oil to the hydraulic actuator is increased or decreased according to the vehicle speed information, that is, the discharge amount during low speed traveling And at the same time, the discharge amount during high-speed running is reduced to increase the steering resistance, thereby ensuring the steering stability.

Incidentally, in order to further reduce the driving energy of the power steering pump used in the power steering apparatus, a load pressure sensitive mechanism is provided in the hydraulic circuit, whereby the discharge amount of pressure oil to the hydraulic actuator side is reduced during non-steering. One example is disclosed in
No. 278,622. Further, an example of a power steering pump control device provided with a flow rate control means of a vehicle speed sensitive type has been proposed by the present applicant in the specification and drawings of Japanese Patent Application No. 6-278622.

Here, the steering wheel angle is read, and it is determined whether or not the difference between the previous value and the current value exceeds a set value. If the difference is exceeded, a command to increase the discharge amount of the power steering pump, that is, a command to the hydraulic actuator side, is issued as steering. The amount of pressure oil discharged is increased to increase the steering assist force and reduce the amount of direct return to the pump. At this time, as the vehicle speed increases, the discharge amount of the pressure oil is reduced, and the steering stability is secured. Conversely, if the deviation between the previous value and the current value of the steering wheel angle is smaller than the set value, the process waits for the elapse of a predetermined time. During this time, if the calculated lateral acceleration exceeds the set value, it is considered that the steering is being performed. Unless a predetermined time elapses, the non-steering operation is determined. At this time, a discharge amount reduction command of the power steering pump is issued, that is, the pressure oil discharge amount to the hydraulic actuator side is reduced, the steering assist is stopped, and the direct return amount to the power steering pump is increased,
We are trying to save energy.

[0007]

SUMMARY OF THE INVENTION As described above, Japanese Patent Application No. Hei.
The power steering pump control device proposed in -278622 is a vehicle speed sensitive type, which can secure steering stability at high speeds, and has a steering angle change and a calculated lateral acceleration at a low level for a certain period of time or less. At the time of non-steering including the state, the steering assist is stopped to reduce the amount of pressure oil discharged to the hydraulic actuator, thereby achieving energy saving.

However, here, the calculated lateral acceleration is calculated from the vehicle speed and the steering wheel angle, and the steering area and the non-steering area are determined based on whether or not the calculated lateral acceleration exceeds a threshold value. Regardless, the calculated lateral acceleration is used in all vehicle speed ranges. However, at an extremely low speed or at a stop, the calculated lateral acceleration cannot be accurately calculated due to inaccurate determination of the vehicle speed. In such a situation where the calculated lateral acceleration cannot be predicted, an energy-saving driving range (steering assist stop range) is accurately obtained. Cannot be determined, and there is a problem in further expanding the energy saving operation range and improving fuel efficiency.

In this case, a hydraulic pressure sensor is used to detect the hydraulic pressure of the discharge path following the steering gear box and the hydraulic actuator, and if the discharge pressure of the discharge path is relatively small, it is regarded as an energy saving operation range. Conversely, if it is relatively large, it may be regarded as a steering assist area and the flow rate adjustment control may be performed. However, in this case, a hydraulic sensor as an additional component causes an increase in cost, which is a problem. An object of the present invention is to accurately determine an energy-saving operation range even at an extremely low speed or at a stop,
An object of the present invention is to provide a power steering pump control device capable of expanding an energy-saving operation range and improving fuel efficiency without increasing costs.

[0010]

A first aspect of the present invention is a power steering pump control device for reducing the discharge flow rate of a hydraulic pump driven by an engine or the like when the vehicle is not being steered. When the vehicle speed is equal to or less than a predetermined value from the signal from the vehicle speed detection means and the vehicle is in the steering holding state according to the signal from the steering state determination means, that is, when the vehicle speed reaches the predetermined value or less, the steering operation is stopped. The tire is determined to remain in the state, and when such a determination is made, the tire generated lateral force is predicted to be zero, so the discharge flow rate of the hydraulic pump is suppressed, the steering assist is stopped, and the power steering pump is stopped. By directly increasing the return amount, the hydraulic pump can be held in the energy saving area, the energy saving area can be expanded to improve fuel efficiency, and in this case, the vehicle speed sensor can accurately detect the vehicle speed, Saving energy range can be judged to sure.

According to a second aspect of the present invention, in the power steering pump control device according to the first aspect, in particular, the control means first obtains a reference steering angle when suppressing the discharge flow rate of the hydraulic pump. When returning to the next steering state after exiting the steering state while maintaining the vehicle speed at or below the predetermined value, the deviation between the steering angle at the time of the return and the reference steering angle is obtained, and the deviation is within the allowable value. , The hydraulic pump discharge flow rate is suppressed, steering assist is stopped, the amount of direct return to the power steering pump is increased, and the hydraulic pump is held in the energy saving area, thereby returning to the energy saving area. Frequency can be increased.

According to a third aspect of the present invention, in the power steering pump control device according to the first aspect, in particular, the steering angle at the time of steering is stored when the steering state is determined by the steering state determining means. Thereafter, when the next steering-holding state is determined again after exiting the steering-holding state, the current steering angle becomes the steering-holding steering angle in the previous steering-holding state within a preset steering-holding determination time. When returning, it is determined that the vehicle has returned to the next steering state, so that the frequency of returning to the next steering state can be increased.

According to a fourth aspect of the present invention, in the power steering pump control device according to the third aspect, in particular, the steering angle at the time of steering is stored when the steering state is determined by the steering state determining means. Then, after exiting the steering state, when entering the next steering state determination, the steering angle at the previous steering state in the previous steering state within the preset steering determination time is set to the current steering angle. Returns and the steering angular velocity is equal to or less than the set angular velocity,
Since it is determined that the vehicle has returned to the next steering state, the frequency of returning to the next steering state increases, and when the steering wheel angular velocity is relatively large, such as during slalom driving, steering is performed here. Return to the state can be suppressed.

[0014]

FIG. 1 shows a power steering pump control device as an embodiment of the present invention. The power steering pump control device 10 is mounted on a power steering device PS of a passenger car (not shown). Here, the power steering device PS is the reservoir tank 1
The first oil is pressurized by a hydraulic pump (hereinafter simply referred to as a pump) 12 driven by an engine (not shown), and flows through a flow control unit 13 and a discharge path R1 supported by a casing 121 of the pump 12 so that the oil in a steering gear box (not shown) is formed. It is supplied to a hydraulic valve 14 and a hydraulic cylinder 15 as a hydraulic actuator.

The hydraulic valve 14 is used to control the hydraulic cylinder 1 during steering.
The switching operation is performed to selectively supply high-pressure oil to the left and right high-pressure chambers 16 and 17, and the steering force of the driver is reduced by the hydraulic steering force (steering assist force) generated by the hydraulic cylinder 15. Return oil from chambers 16 and 17 is low pressure line 1
8 and flows into the reservoir tank 11. Here, when the handle H is turned to the right, the hydraulic valve 14
Moves to the right in FIG.
The pressure oil is supplied from the side and the oil in the right high-pressure chamber 17 is discharged to the low-pressure path 18. At this time, a steering assist force for turning the steering wheel H to the right is generated in the left high-pressure chamber 16. Conversely, when the handle H is turned to the left, the valve element 141 moves to the left in FIG. 1, supplies pressure oil to the right high-pressure chamber 17 from the discharge path R1 side, and supplies oil in the left high-pressure chamber 16 to the low pressure path 18. At this time, a steering assist force for turning the steering wheel H to the left is generated in the right high-pressure chamber 17.

The power steering pump control device 10 includes a flow control unit 13 supported by a casing 121 of the pump 12 and a controller 25 as control means.
It is composed of The flow control unit 13 includes a throttle unit 21 on the discharge path R1, a branch chamber 22 positioned upstream of the discharge path R1 with respect to the throttle unit 21, and a flow control valve disposed opposite the throttle unit 21 via the branch chamber 22. 23, and an electromagnetic valve 24 for adjusting the exhaust pressure of the flow control valve via an exhaust pressure adjusting unit 31.
Note that a controller 25 is connected to the solenoid valve 24.
The pump 12 is a well-known vane pump, and is driven by receiving rotation of an engine (not shown) via a rotation transmission system (not shown).

Here, the throttle portion 2 is provided in the casing 121.
1, a branch chamber 22, a flow control valve 23, a pressure chamber 29, and a solenoid valve 24 are arranged in series in this order.
Is provided with an inflow port 26 into which pressure oil from the pump 12 flows and a return port 2 following a return path 27 to the reservoir tank 11.
8 are formed by extension. The hydraulic pressure of the discharge port 20 is guided to the pressure chamber 29 via the communication passage 30, and the pressure chamber is connected to the return path 2 via the exhaust pressure adjusting unit 31 and the second return port 32.
7 is connected.

The throttle section 21 constitutes an inflow flow rate-responsive flow rate adjusting mechanism for variably setting the flow rate to the discharge port 20 according to the inflow pressure of the inflow port 26. That is, the throttle section 21 is provided with a fixed orifice 33 and a variable orifice 34,
The variable orifice 34 includes a plunger 36 that is urged open by a spring 35. The hydraulic pressure of the inflow port 26 is provided on the back of the plunger 36 by the pilot port 37.
Has been added through. Therefore, when the pump 12 is in the low rotation range (see the E1 region in FIG. 8), the inflow port 26
Is low, the variable orifice 34 opens widely, and a relatively large amount of pressure oil is supplied to the hydraulic valve 14 and the hydraulic cylinder 15 through the discharge port 20 through the variable orifice 34 and the fixed orifice 33, so that the steering assist force can be exerted. .

When the pump 12 is in the middle rotation range (see the area E2 in FIG. 8), the flow rate and the pressure increase, but the plunger 36
The pressure of the variable orifice 34 is restricted by the hydraulic pressure of the inflow port 26 through the pilot port 37 on the back of the valve, and the flow rate of the hydraulic oil supplied to the hydraulic valve 14 and the hydraulic cylinder 15 is regulated by the variable orifice 34, As the oil pressure at 22 increases, the flow control valve 23 opens as described later, and the flow to the return path 28 increases. For this reason, a relatively small amount of pressure oil is discharged to the hydraulic valve 14 and the hydraulic cylinder 15 through the discharge port 20 through the throttle 21.

Further, the pump 12 is operated in a high rotation range (E3 in FIG. 8).
When the variable orifice 34 reaches the maximum value, the flow control valve 23 opens to the maximum as described later, the flow rate to the return path 28 increases, and the flow rate to the hydraulic valve 14 and the hydraulic cylinder 15 side increases. The discharge amount of pressure oil is further reduced,
It is kept approximately constant. The flow control valve 23 is connected to the branch chamber 22.
The flow rate of the hydraulic oil discharged to the discharge port 20 side is controlled by adjusting the flow rate returned from the return path 28 to the return path 28. The flow control valve 23 separates the branch chamber 22 and the pressure chamber 29 and returns the valve body 38 and the valve body 38 slidably provided so as to increase or decrease the flow path area of the return port 28 leading to the reservoir tank 11. An urging spring 39 for urging the flow path area of the port 28 in a direction to reduce the flow path area, and a discharge pressure adjusting unit 31 are provided.

In the valve body 38, the hydraulic pressure of the pressure chamber 29,
That is, when the oil pressure on the discharge port 20 side is excessively increased, the pressure regulating valve 4 that allows the oil to escape from the pressure chamber 29 to the return path 28.
0 is attached. Thus, the discharge path 2 which is a pump load
When the oil pressure on the 0 side suddenly increases in a stationary state where the steering amount of the power steering device PS becomes particularly large, for example,
This hydraulic pressure can be eliminated.

The exhaust pressure adjusting section 31 comprises a valve seat 311 and a valve body 312 which comes into contact with and separates from the valve seat 311. The valve body 312 variably sets the flow rate adjustment amount of the flow rate control valve 23, and is driven by the electromagnetic valve 24. Is done. The solenoid valve 24 is a duty valve,
A valve body 312 that comes in contact with and separates from the valve seat 311, a casing 241 that slidably supports the valve body 312, a movable iron core 242 provided at the center of the casing, and separates the movable iron core from the valve body 312. And a solenoid 244 that moves the movable iron core 242 in the valve closing direction C against the elastic force of the spring 243. Note that a proportional control valve (not shown) may be used instead of the solenoid valve 24 which is a duty valve.

When the solenoid valve 24 is turned on, the valve seat 31 is turned on.
1 is brought into contact with the valve element 312. Here, the duty ratio D, which is the ratio of the closing time t per unit time T, is used.
Opening / closing operation is performed according to u, and the hydraulic pressure of the pressure chamber 29 is increased or decreased by a throttle action corresponding to the duty ratio Du. That is, as shown in FIG. 2, when the duty ratio Du is large (100 side) and the equivalent orifice area is squeezed small, the back pressure increases, and the valve body 38 is placed in the pressure chamber 2.
The combined force of the hydraulic pressure of No. 9 and the pressing force of the urging spring 39 moves to a position where it balances the hydraulic pressure of the branch chamber 22, that is, in this case, moves to the left and regulates the flow to the return path 28 side. Thus, the flow of oil from the throttle section 21 to the hydraulic valve 14 and the hydraulic cylinder 15 side is promoted, and steering assist can be positively performed.

On the other hand, when the duty ratio Du is small (0
Side), when the equivalent orifice area is wide open, the back pressure becomes small, and the valve body 38 is moved to the right fully open position B1.
(See FIG. 1), the return path 28 is fully opened, the discharge amount from the discharge path 20 toward the hydraulic valve 14 and the hydraulic cylinder 15 is minimized, and the flow rate to the return path 28 is maximized and returned to the reservoir tank 11. Energy saving can be achieved.

The controller 25 as a control means detects a steering angle (here, it is regarded as a steering angle) θ from a vehicle speed Vel in a driving state from a vehicle speed sensor 41 serving as a vehicle speed detecting means.
h is taken in from a steering wheel angle sensor 42 serving as a steering angle detecting means, and the supply of hydraulic pressure to the hydraulic valve 14 and the hydraulic cylinder 15 is controlled according to these values. That is, here, the duty ratio map M1 corresponding to the vehicle speed shown in FIGS. 3 to 5, the duty ratio map M2 corresponding to the steering wheel angular velocity (considered as the steering angular velocity), the calculated lateral acceleration threshold map M
3, the flow control process shown in FIGS. 10 to 14 is performed, the output V of the duty ratio Du which is the control target is determined, and the solenoid valve 24 is driven with the same duty output.

The duty ratio map M1 corresponding to the vehicle speed
Means that the steering force assisting characteristic is enhanced at low speed, and the duty ratio is decreased as the vehicle speed (Vel) increases, that is, the vehicle speed coefficient K
V is set small, thereby increasing the steering wheel steering force at high speeds and ensuring steering stability at high speeds. Further, the steering angular velocity corresponding duty ratio map M2 sets a small steering angular velocity coefficient Kh in a region where the steering angular velocity ωdeg / sec is small, suppresses steering assist, prevents a decrease in fuel consumption, and performs steering as the steering angular velocity increases. It is set to increase the assist and achieve a light steering force at the time of stationary steering. Further, the calculated lateral acceleration threshold map M3 sets a calculated lateral acceleration to the extent that a tire generated lateral force is applied to the vehicle and steering assist is required, as a threshold,
For example, 0.05 g is set here, steering assist is required in a hatched area in FIG. 5 that is larger than this threshold, and energy saving operation (hydraulic pump is not operated) is performed in a non-hatched area (steering area). Set.

The operation of the controller 25 of the power steering pump control device 10 will be described with reference to FIGS.
Will be described with reference to the control routine shown in FIG. The controller 25 enters a main routine control process when an engine key (not shown) is turned on.

In this main routine, in step s1, circuit failure judgment of each sensor and the solenoid valve 24, etc., the timer TM, the pump flag PFLG, the steering flag HFLG, the running flag VFLG, and the start flag SFLG are cleared, and the initial setting is performed. Do. In step s2 Then, the vehicle speed sensor 41, from the steering wheel angle sensor 42, vehicle speed Vel, the steering wheel angle [theta] h reads, based on the current steering wheel angle [theta] h and the previous wheel angle [theta] h _O control cycle Δt wheel angular velocity ωdeg / sec (= (Θh _O −θ
h) / Δt) is calculated. In step s3, a vehicle speed determination routine is executed. In step s4, a steering / non-steering determination routine is executed to function as a steering holding state determination unit. In step s5, a pump control determination routine is executed. In step s6, a drive voltage routine is executed. And completes one control cycle, and returns to step s2.

In the vehicle speed determination routine, it is determined in step a1 whether or not the current vehicle speed Vel exceeds the high threshold value VmH (see FIG. 6).
a4: Allowable steering wheel deflection angle Aho for running, described later in a4
Is set to 4 °, the running flag VFLG is set to “1”, the start flag SFLG is cleared, and the process returns to the main routine. On the other hand, from step a1, the current vehicle speed Vel becomes higher
H (for example, 4 km / h), and
, The current vehicle speed Vel decreases to a low threshold value VmL (for example, 3K
m / h), the program returns to the main routine as it is if it exceeds, and if it does not (time t1 in FIG. 9), the process proceeds to step a6. Is set to 2 °, the running flag VFLG is cleared, and the routine returns to the main routine.

In the steering and non-steering determination routine, as shown in FIG. 12, it is determined in step b1 whether or not the current absolute value of the steering wheel angle θh is 180 ° or more.
It is considered that the steering assist is required at 2 and the steering flag HFLG
Is returned to the main routine. If the angle falls below 180 °, it is determined in step b3 whether or not the previous value θho and the current value θh match. If the value matches, the process proceeds to step b7. The absolute value Δθh of the deviation between θho and the current value θh is determined, and it is determined whether or not the deviation is equal to or greater than the allowable handle deflection angle Aho determined in the vehicle speed determination routine of FIG. In this case, 4 ° when driving, 2 ° when stopped
Are used as allowable values.

If the current steering angle is larger than the permissible value Aho, the operation proceeds to step b6, the previous value θho is updated with the current value θh, and the operation proceeds to step b2. If the steering angle is smaller than the allowable value Aho, the process proceeds to steps b7 to b8. When this step b7 is reached (see time t2), it is regarded as a non-steering state, and the timer count value TM (started in steps b10 and b12 described later) is added for one control cycle INT to calculate the calculated lateral acceleration. . Here, using the current vehicle speed Vel and the steering wheel angle θh, the absolute value | Yg | of the calculated lateral acceleration is obtained by a known calculation process, and the process proceeds to step b9. In step b9, a tire generated lateral force is applied to the vehicle, and a threshold value of 0.05 g considered to require steering assist is used.
It is determined whether or not Yg | is equal to or greater than the threshold value 0.05 g. At this point, it is determined that the steering assist is being performed, and the process proceeds to step b10, the timer count value TM is cleared, the process proceeds to step b2, and the steering flag HFLG is set to "1". Otherwise, the process proceeds to step b11.

In step b11, the timer count value TM is set to 1.
Wait for 5 seconds or more. At this time, the process first returns to the main routine, and after 1.5 seconds has elapsed (time t3
Steps b12 to b13), clear the timer count value TM, clear the steering flag HFLG,
It is considered that the steering is being held (when 1.5 sec has elapsed without steering), and the process returns to the main routine. Note that the above-described control processing of the steering / non-steering determination routine functions as a steering state determination unit that determines a steering state based on a signal from the steering angle detection unit.

In the pump control determination routine, as shown in FIG. 13, it is determined in step c1 whether or not the latest traveling flag VFLG is "0". In the case of "1", whether or not the steering flag HFLG is "0" in step c2. If it is determined that the vehicle is not steered "0", it is regarded as straight running, and the process proceeds to step c3, where the pump flag PFLG is cleared, that is, the control is started in a straight running range where steering assist is not required. Return to routine. On the other hand, in step c2, when the steering is performed with the steering flag HFLG set to "1", it is determined that steering assist is necessary because the vehicle is traveling, and the pump flag PFLG is set to "1", and the process returns to the main routine. On the other hand, in step c1, the traveling flag VFLG is set to "0", that is, 3 km / h.
If it is determined that the time is the following stop, the process proceeds to step c5,
Here, it is determined whether or not the current steering flag HFLG is “0”. If the steering is maintained (HFLG = 0), the process proceeds to step c6, and if not, the process proceeds to step c7.

When the vehicle enters a stop state of 3 km / h or less and reaches step c6 assuming that the vehicle is in a steering-holding state, here, further,
It is determined whether the start flag SFLG is "1" or not, and 3 km
/ H, the start flag SFLG is 0 at the first time when the vehicle enters the steering-holding state at the time of the stop at the time t.
In step 1, the process proceeds to steps c8 to c11. Here, the start flag SFLG is set to “1”, the current steering wheel angle θh is set as the reference steering angle HaoT (see FIG. 7), and the value of the maximum deviation angle HaM (displacement with respect to the reference steering angle HaoT) described later is cleared. Then, the pump flag PFLG is cleared. This driving range is considered to be a range e (see FIG. 9) in which the vehicle is not likely to be subjected to a tire-generated lateral force and does not require steering assist because the vehicle is in a steering maintained state at a stop of 3 km / h or less. And returns to the main routine.

On the other hand, when the process reaches step c6 again, the start flag SFLG is "1", and the process proceeds to step c12. Here, it is determined whether or not the maximum deviation angle HaM exceeds 10 ° (see FIG. 7). If the maximum deviation angle HaM exceeds, that is, if the deviation of the steering wheel angle θh from the reference steering angle HaoT is large, it is determined that the steering assist is necessary. Proceed to c4, otherwise proceed to step c13.

In step c13, the absolute value of the deviation between the current steering wheel angle θh and the reference steering angle HaoT is calculated using the reference steering angle HaoT when the steering state is entered for the first time at a stop of 3 km / h or less. , If the value falls below the set value of 4 °,
Assuming that the steering assist is not required as before, the routine proceeds to step c11, where the pump flag PFLG is cleared. Conversely, when the set value exceeds 4 ° (see time point t4), the current steering wheel angle θh is used as a reference. It is considered that the steering angle is different from the steering angle HaoT and the necessity of the steering assist has occurred, and the routine proceeds to step c4, where the pump flag PFLG is set to “1”. After this, steps c6, c12, c13, c1 are performed again.
1 at time t1 ', a mode in which the steering maintained state is continued assuming that the area e does not require the steering assist.

Next, from step c5 to step c
When the speed reaches 7, the stop time of 3 km / h or less continues, but there is a case where the state is switched to the steering state.
The current steering wheel angle θh and the previously set reference steering angle Hao
The absolute value ΔHaT (see FIG. 7) of the deviation from T is calculated, and the process proceeds to step c14, where the deviation amount ΔHaT from the steering hold is calculated.
Is smaller than the current maximum deviation amount HaM, and if it is, the process directly proceeds to step c4, where the current maximum deviation amount HaM is obtained.
If it exceeds M (see time point ta in FIG. 7), step c15
And the current maximum deviation amount HaM is changed to the current deviation amount Δ
The process is updated to HaT, and then the process proceeds to step c4, where it is assumed that steering assist has been performed (see time point t5 in FIG. 9), the pump flag PFLG is set to "1", and the process returns to the main routine.

The control processing of steps c1, c4, c5, c6, c8 to c13 in the above-described pump control determination routine functions as the control means in the present invention. In the drive voltage routine, as shown in FIG. 14, at step d1, it is determined whether or not the current pump flag PFLG is "1". At "0", since steering assist is unnecessary, the process proceeds to step d3, and the duty The ratio Du is set to a small value (for example, duty ratio 0 in FIG. 2), the solenoid valve 24 is driven with the output V of the same duty ratio Du, and the process returns to the main routine. On the other hand, at step d1, the current pump flag PFL
If G is "1", it is considered that steering assist is required,
Proceeding to step d2, the setting coefficient KV of the duty ratio Du corresponding to the current vehicle speed Vel is obtained from the map M1, the setting coefficient Kh of the duty ratio Du corresponding to the current steering wheel angular velocity ωdeg / sec is obtained from the map M2, and their multiplication values are obtained. The electromagnetic valve 24 is driven with the output V, and the process returns to the main routine.

As described above, the power steering pump control device shown in FIG. 1 properly drives the power steering device PS to generate a steering assist force during the steering assist (when step c4 is reached). On the other hand, when the vehicle speed reaches a stop area below a predetermined value (for example, 3 km / h),
If the steering is maintained (steering flag HFLG = 1),
Since the tire generated lateral force is predicted to be zero, that is,
In the case of a temporary stop at the time of turning right or left, the return path 28 is fully opened to reduce the discharge amount to the discharge path 20 side,
The hydraulic pump 12 can be reliably operated in the energy saving area (steps c8 to c11), the energy saving area can be expanded, and the fuel efficiency can be improved.

Moreover, when the discharge flow rate of the hydraulic pump is suppressed (when the flow proceeds from step c6 to the c8 side), the reference steering angle Ha
oT is obtained (see step c9), and thereafter, the vehicle speed is maintained at or below a predetermined value (steps c1 and c5).
When returning to the next steering holding state after exiting from the steering holding state at step, a deviation between the steering wheel angle θh and the reference steering angle HaoT at the time of the return is obtained (see step c13), and the deviation is an allowable value (for example, 4). °), the discharge flow rate of the hydraulic pump is suppressed (see step c11), the steering assist is stopped, the amount of direct return to the power steering pump is increased, and the hydraulic pump is maintained in the energy saving region. In this case, in order to determine whether the deviation between the steering angle at the time of returning to the steering holding state and the previously obtained reference steering angle is within the allowable value, the accuracy of returning to the energy saving range can be increased, and the allowable value can be increased. By adjusting (for example, 4 °), it is possible to provide a degree of freedom in adjusting the frequency of returning to the energy saving region.

In the power steering pump control device shown in FIG. 1, the steering-holding state judging means keeps the non-steer state (steps b3 to b5, steps b7 to b9) and returns to step b.
11 and when a predetermined time (for example, 1.5 sec) has elapsed, the state of the steering wheel is determined, and the process reaches steps b11 to b13, and the steering flag HFLG is set to "0". Instead of this, a power steering pump control device that performs the steering / non-steering determination processing as shown in FIGS. 15 and 16 may be configured. The configuration of the power steering pump control device here is the same as that of the device of FIG. 1 except for the steering and non-steering determination processing, and thus redundant description is omitted here.
Further, each of the steering and non-steering determination processing shown in FIGS. 15 and 16 has many parts that are the same as the processing of FIG. 12, and here the same processing is given the same step number, and the repeated description is simplified.

When the steering / non-steering operation determining step b1 shown in FIG. 15 is reached, the absolute value of the steering wheel angle θh becomes 180.
°, the steering flag HFLG is set to “1” (step b).
2), and then proceeds to step b3, where the previous value θ
ho and the current value θh are compared. If θho = θh, go to step b7; otherwise, go to step b4 to find the deviation Δθh = | θ
ho−θh |, and the deviation is calculated as the allowable value of the handle deflection angle A.
It is determined whether or not ho (4 ° or 2 °) or more. If the steering angle is large, the process proceeds to step b6, the previous value θho is updated with the current value θh, and the process proceeds to step b14.

In step b14, it is determined whether or not the timer count value TM (cleared in steps b10 and b12) has not reached 1.5 sec. If not, the process proceeds to step b15. Using the steering angle θhs during steering, it is determined whether the current steering wheel angle θh matches the steering angle θhs during steering, and if not, step b2
Then, the steering flag HFLG is set to "1", and the steering assist area is determined. On the other hand, if the current steering wheel angle θh matches the steering angle θhs during steering, the process proceeds to step b16, where the current steering wheel angle θh returns to the steering angle θhs during steering, and it is considered that the necessity of the steering assist has been eliminated. Steering flag HF
Clear LG and return to the main routine. After the elapse of 1.5 seconds in step b14, the flow advances to step b2 to set the steering flag HFLG to "1".

In step b5, the handle shake angle Δθh is smaller than the allowable handle shake angle value Aho.
When the routine proceeds to 8, it is regarded as a non-steering state, the timer count value TM is added for one control cycle INT, a calculated lateral acceleration is calculated, and the routine proceeds to step b9. Here, it is determined whether or not the absolute value | Yg | of the current calculated lateral acceleration is equal to or more than a threshold value 0.05 g at which the steering assist is considered to be necessary. If not, the process proceeds to step b10 on the steering assist side; Proceed to. In step b11, the process waits for the timer count value TM to reach 1.5 seconds or more. At that point, the process proceeds to steps b12 and b13, where the timer count value TM is cleared, and when the steering is maintained (for 1.5 seconds without steering).
Is elapsed), and the steering flag HFLG is cleared. Next, in step b17, the current steering wheel angle θh is set as the steering-holding steering angle θhs, and the process returns to the main routine.

Thus, here, in particular, step b
At the time point when the steering-holding determination is made in step 11, the current steering wheel angle θh is set as the steering-holding steering angle θhs in step b17. (Steps b3 to b5), the current steering wheel angle θh returns to the previously set steering angle θhs in the previous steering state within the preset steering determination time 1.5 sec (step b3). b5, b6, b14, b15), and it is determined that the vehicle has returned to the next steering holding state, and the steering flag HFLG is cleared in step b16. For this reason, even if the current steering wheel angle exceeds the allowable steering wheel deflection value Aho, when the current steering wheel angle returns to the previously set steering-preserving steering angle θhs, the vehicle can be returned to the next steering state. The frequency of returning to the next steering holding state increases, and the energy saving operation range can be expanded.

The steering / non-steering determination process shown in FIG.
Step b1 is compared with the steering / non-steering determination process shown in FIG.
Since the processing is the same except for the point that the processing of 5 ′ is different, repeated description is omitted. It is assumed that the process reaches step b15 'of the steering / non-steering determination process shown in FIG.

In this case, the handle deflection angle Δθh is larger than the handle deflection angle allowable value Aho (Ye in step b5).
s side determination), the time when the timer count value TM does not reach 1.5 sec (No side determination in step b14)
Here, the current steering wheel angle θh returns to the steering-preserving steering angle θhs (set in step b17 in the previous control cycle) in the previous steering holding state set within 1.5 sec, and the latest steering wheel angular velocity. It is determined whether or not ωdeg / sec (calculated in step s2) is equal to or less than a set angular velocity (for example, 10 deg / sec). In this case, in Yes, it is determined that the steering of the steering wheel has touched in the direction to return to the original state, and it has been returned to the next steering holding state, it is considered that the steering assist is not necessary, and the steering flag HFLG is cleared in step b16. If No, the steering flag HFLG is set to "1" and the process returns to the main routine.

Thus, here, in particular, step b
At the time point when the steering-holding determination is made in step 11, the current steering wheel angle θh is set as the steering-holding steering angle θhs in step b17. (Steps b3 to b5), the current steering wheel angle θh returns to the preceding steering angle θhs within the steering-holding determination time 1.5 sec, and the steering wheel angular velocity ωdeg / sec becomes the set angular velocity (for example, 10 deg / sec). If the following (steps b5, b6, b14, b15 'side), it is determined that the vehicle has returned to the next steering holding state, and the steering flag H is determined in step b16.
Clear FLG. Therefore, even if the current steering wheel angle exceeds the allowable steering wheel deflection angle value Aho, when the current steering wheel angle returns to the previously set steering steering angle θhs, it is possible to return to the next steering state, and At this time, if the steering wheel angular velocity is relatively high as in the case of slalom running, the return here can be suppressed, and hunting for switching the operating range can be prevented.

[0049]

As described above, according to the present invention, normally, the power steering device is accurately driven to generate a steering assist force, and the vehicle speed reaches a predetermined value or less while maintaining the steering state, In the case of a temporary stop at the time of a left turn, the hydraulic pump can be reliably operated in the energy saving area, the energy saving area can be expanded, and the fuel efficiency can be improved. Moreover, in this case, the vehicle speed can be determined to be equal to or less than a predetermined value while the vehicle speed sensor detects the vehicle speed accurately, so that the energy saving region can be accurately determined, and additional components such as a hydraulic sensor are not required, resulting in an increase in cost. Not even.

According to a second aspect of the present invention, in the power steering pump control device according to the first aspect, a reference steering angle is obtained particularly when the discharge flow rate of the hydraulic pump is suppressed, and thereafter, the vehicle speed is maintained at a predetermined value or less. When the vehicle returns to the next steering state after exiting the steering state while keeping the steering angle, the deviation between the steering angle at the time of the return and the reference steering angle is obtained, and if the deviation is within the allowable value, the hydraulic pump Suppress the discharge flow rate and stop steering assist. Therefore, in order to determine whether the deviation between the steering angle when returning to the next steering holding state and the previously obtained reference steering angle is within an allowable value, the frequency of returning to the energy saving region can be increased, The degree of freedom in adjusting the frequency of returning to the energy saving range can be given by adjusting the allowable value.

According to a third aspect of the present invention, there is provided the power steering pump control device according to the first aspect, in which the steering angle at the time of steering is stored when the steering state is determined, and then the steering angle is released after the steering state is released. When the current steering angle returns to the steering angle in the previous steering state within the preset steering determination time when entering the next steering state determination, the state returns to the next steering state. It is determined that it has been performed. For this reason, if the current steering angle returns to the steering angle during the previous holding state within the preset steering holding determination time, it is possible to return to the next steering state, and thus return to the next steering state. And the energy saving operation range can be expanded.

According to a fourth aspect of the present invention, in the power steering pump control device according to the third aspect, in particular, the steering angle at the time of steering is stored when the steering state is determined, and after the steering state is released, When the next steering state is determined, the current steering angle returns to the steering angle at the time of steering in the previous steering state within the preset steering determination time, and the steering angular velocity is lower than the set angular velocity. If there is, it is determined that the vehicle has returned to the next steering state. For this reason, if the current steering angle returns to the steering angle in the previous steering state within the preset steering determination time, and if the steering wheel angular velocity is equal to or less than the set angular velocity, the vehicle returns to the next steering state. Therefore, the frequency of returning to the next steering-holding state increases, and when the steering wheel angular velocity is relatively high, such as during slalom running, the return can be suppressed, and hunting of operating range switching can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a power steering device including a power steering pump control device as one embodiment of the present invention.

FIG. 2 is a characteristic diagram of a pump rotation speed-discharge flow rate of the power steering pump control device of FIG. 1;

FIG. 3 is a characteristic diagram of a vehicle speed coefficient map used by the power steering pump control device of FIG. 1;

FIG. 4 is a characteristic diagram of a steering wheel angular velocity coefficient map used by the power steering pump control device of FIG. 1;

FIG. 5 is a threshold characteristic diagram of a calculated lateral acceleration corresponding to the vehicle speed-the steering wheel angle used by the power steering pump control device of FIG. 1;

FIG. 6 is a vehicle speed determination characteristic diagram used by the power steering pump control device of FIG. 1;

FIG. 7 is a characteristic diagram of a steering wheel angle with time used by the power steering pump control device of FIG. 1;

FIG. 8 is a pump discharge amount characteristic diagram used by the power steering pump control device of FIG. 1;

FIG. 9 is a time-dependent characteristic diagram of a control function of the power steering pump control device of FIG. 1;

FIG. 10 is a flowchart of a main routine used by a controller of the power steering pump control device of FIG. 1;

FIG. 11 is a flowchart of a vehicle speed determination process used by a controller of the power steering pump control device of FIG. 1;

FIG. 12 is a flowchart of a steering / non-steering determination process used by a controller of the power steering pump control device of FIG. 1;

FIG. 13 is a flowchart of a pump control determination process used by a controller of the power steering pump control device of FIG. 1;

FIG. 14 is a flowchart of a drive voltage process used by a controller of the power steering pump control device of FIG. 1;

FIG. 15 shows another steering used by the controller of the power steering pump control device according to another embodiment of the present invention;
It is a flowchart of a non-steering determination process.

FIG. 16 shows another steering used by the controller of the power steering pump control device according to another embodiment of the present invention;
It is a flowchart of a non-steering determination process.

[Explanation of symbols]

Reference Signs List 10 power steering pump control device 12 hydraulic pump 14 hydraulic valve 15 hydraulic cylinder 25 controller (steering state determination means, control means) 41 vehicle speed sensor 42 handle angle sensor θh handle angle Vel vehicle speed Δθh handle angle deviation ω handle angular velocity Yg calculated lateral acceleration PS Power steering pump

Claims (4)

[Claims] 1. A power steering pump control device for reducing a discharge flow rate of a hydraulic pump driven by an engine or the like when a vehicle is not steering, a vehicle speed detecting means for detecting a vehicle speed of the vehicle, and detecting a steering angle of the vehicle. Steering angle detecting means, a steering state determining means for determining a steering state from a signal from the steering angle detecting means, and a steering state determining means when the vehicle speed is equal to or less than a predetermined value from a signal from the vehicle speed detecting means. A power steering pump control device, comprising: a determination unit that determines that the vehicle is in a steering maintaining state based on a signal from the control unit; and a control unit that suppresses a discharge flow rate of the hydraulic pump when the determination is made. 2. The power steering pump control device according to claim 1, wherein the control means stores a steering angle at that time as a reference steering angle when suppressing a discharge flow rate of the hydraulic pump, and thereafter, the vehicle speed is set to a predetermined value. When the vehicle returns to the next steering state after exiting the steering state while being held at or below the value, the deviation between the steering angle at the time of the return and the reference steering angle is obtained, and the deviation is within an allowable value. And a power steering pump control device, wherein a discharge flow rate of the hydraulic pump is suppressed. 3. The power steering pump control device according to claim 1, wherein the steering state determination means stores the steering angle at that time as the steering angle at the time of determining the steering state, and thereafter stores the steering angle. When exiting the state and entering the judgment of the next steering state again,
When the current steering angle returns to the steering-holding steering angle within a preset steering-holding determination time, it is determined that the vehicle has returned to the next steering-holding state. 4. The power steering pump control device according to claim 3, wherein the steering state determination means sets the holding state within a preset steering determination time when starting the next steering state determination. A power steering pump control device, wherein when the current steering angle returns to the steering angle and the steering wheel angular velocity is equal to or lower than the set angular velocity, it is determined that the steering operation has returned to the next steering state.