JP2816462B2 - Electric hydraulic power steering system for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering device provided in a motor vehicle or the like for assisting a steering operation on a steered wheel thereof, and more particularly to a vehicle for obtaining operating hydraulic pressure by an electric hydraulic pump whose output can be easily controlled. The present invention relates to an electric hydraulic power steering device.

[0002]

2. Description of the Related Art In recent years, in automobiles and the like, power steering devices that can reduce the steering wheel operation at the time of steering have become widespread. Such power steering devices are of a hydraulic type or an electric type. In general, stable steering assisting force (steering assist force)
Many of them are hydraulic type that are easy to obtain.

[0003] Such a hydraulic power steering apparatus generally includes a steering mechanism that steers a front wheel (steered wheel) left and right in accordance with an operation of a steering wheel.
It is equipped with an oil pump that generates an operating oil pressure, a supply / discharge valve that is displaced in accordance with the steering direction by turning the steering wheel, and a hydraulic circuit that connects a power cylinder device (piston mechanism). Generally, an oil pump using a driving engine as a drive source is used as the oil pump, and a supply / discharge valve is provided as a rotary valve on a steering column shaft portion.

[0004] When the rotary valve (supply / discharge valve) is displaced in response to the rotation of the steering wheel and enters a corresponding open / closed state, hydraulic oil is supplied or discharged to the power cylinder device as appropriate, and the power cylinder device is supplied to the power cylinder device. A required steering assist force is applied to the steering mechanism by the generated hydraulic pressure. However, it is not possible to appropriately control the driving force of the steered wheels only by the control means based on the displacement of the rotary valve.

[0005] Therefore, in a conventional power steering apparatus using a driving engine as a drive source, the above-described hydraulic circuit includes:
A reaction force mechanism for varying the steering reaction force and a control valve for controlling the reaction force mechanism are provided so that the assist force can be adjusted, and a vehicle speed sensor for detecting the speed of the vehicle and a steering angle (handle angle) are provided. A steering angle sensor for detecting is provided, and the assist force is controlled based on the detection signals of these sensors, so that an appropriate steering characteristic is obtained.

For example, at the time of steering in the bottom cut and the low speed running range, the assist force is appropriately increased to reduce the steering force, and at the time of steering in the middle to high speed running range, the assist force is appropriately reduced. The steering force is increased so that a sense of steering stability can be obtained. However, such an engine-type power steering device can control the steering force appropriately, but requires a reaction force mechanism and a control valve, and is structurally complicated.

[0007] Further, it is necessary to set the output of the oil pump large so as to obtain a required oil pressure at a low speed, which imposes a heavy load on a traveling engine, which impairs the fuel efficiency of a vehicle. So recently,
Instead of using a running engine, an electric hydraulic pump that uses a battery mounted on the vehicle and an electric motor that operates with an alternator as a power source is used as a driving source, and without using a reaction force mechanism or a control valve, the electric hydraulic pump is used. There has been proposed an electro-hydraulic power steering device capable of appropriately controlling a steering force only by controlling a discharge state.

[0008] With such a device, the assist force control according to the running state is easily and accurately performed.

[0009]

However, in such an electrohydraulic power steering apparatus, since the battery and the alternator are operated using the electric power as a power source, a large load is easily applied to the battery. Therefore, it is necessary to increase the battery capacity. However, the alternator is strengthened with the increase in the battery capacity, and the fuel consumption of the engine of the vehicle is reduced.

Therefore, the conventional electro-hydraulic power steering apparatus is in a wasteful area even when it is operated, when the vehicle speed is, for example, "10 km / h or less" (extremely low speed range), when not operating (when the steering mechanism is not steered). Only in (2), the operation of the electric hydraulic pump is stopped to reduce the load on the battery. However, since power saving is not sufficient even by such means, the stop range of the electric hydraulic pump is not limited to, for example, not only “10 km / h or less” (extremely low speed range), but also when the entire vehicle speed range is not operated. It is possible to expand.

In such a mechanism, power saving is improved and
There is a problem that it is difficult to obtain steering force characteristics at the same time. That is, when the detection sensitivity of the steering state is increased, the minute steering is detected. Therefore, when the power steering apparatus shifts from the non-steering state to the steering state, the startup responsiveness of the electric hydraulic pump can be enhanced. Hydraulic pump operates and power saving cannot be improved.

Conversely, when the detection sensitivity of the steering state is reduced, the time of minute steering cannot be detected, so that the electric hydraulic pump can be stopped at the time of minute steering to improve power saving. When the vehicle shifts from the steering state to the steering state, the startup responsiveness of the electric hydraulic pump deteriorates, and an assist force is generated by the power cylinder device with a delay from the operation of the steering wheel, resulting in a so-called assist delay. For this reason, when the steering is performed suddenly, the steering assist force is not sufficiently obtained, and the operability of the steering wheel is reduced.

The present invention has been devised in view of the above problems, and provides an electro-hydraulic power steering device for a vehicle which is capable of achieving power saving while maintaining good steering force characteristics. The purpose is to:

[0014]

According to a first aspect of the present invention, there is provided an electro-hydraulic power steering apparatus for a vehicle, comprising: a steering mechanism for steering a steering wheel in accordance with an operation of a steering wheel provided in the vehicle; An electric hydraulic pump driven as a source, a piston mechanism attached to the steering mechanism for assisting steering in the steering mechanism, and an electric hydraulic pump for supplying steering piston operating oil to the piston mechanism. A hydraulic circuit interposed between the piston mechanism, a piston mechanism provided to assist the steering in the steering mechanism, a hydraulic circuit connecting the piston mechanism and the electric hydraulic pump, and the steering wheel Steering angle detecting means for detecting a steering angle of the electric hydraulic pump based on a detection signal from the steering angle detecting means. Pump control means for controlling the operation of the pump, wherein the steering angle detected by the steering angle detection means is equal to or less than a predetermined amount and the steering angle detection within a predetermined time is performed.
Means for determining that the vehicle is in the straight running mode when the frequency of change of the detection signal by the means is equal to or greater than a predetermined value, and the pump control means is provided in accordance with the straight running mode determination by the straight running determining means A pump stopping means for stopping the operation of the electric hydraulic pump is provided.

According to a second aspect of the present invention, in addition to the above configuration, when the pump control means enters a non-straight traveling mode in which the straight traveling judging means does not determine the straight traveling mode. It is characterized in that the operation of the electric hydraulic pump is started immediately upon the start of the steering operation based on the information from the steering angle detecting means.

According to a third aspect of the present invention, in addition to the above-described structure, the electric hydraulic power steering apparatus for a vehicle may further include: An operation holding means for holding the operation state for a time is provided.

[0017]

According to the first aspect of the present invention, when the steering wheel is operated, the steered wheels are steered according to the operation by operating the steering wheel. At this time, the electric hydraulic pump operates using the electric motor as a drive source to drive hydraulic oil, and the hydraulic oil is supplied to the piston mechanism through a hydraulic circuit, and the steering in the steering mechanism is assisted by the piston mechanism. .

The operation of the electric hydraulic pump is controlled by the pump control means on the basis of a detection signal from the steering angle detecting means. In particular, the steering angle detected by the steering angle detecting means is determined by the straight traveling determining means by a predetermined amount. Within the specified time
When it is determined that the vehicle is in the straight running mode when the frequency of change of the detection signal by the steering angle detecting means is greater than or equal to a predetermined value, pump stopping means provided in the pump control means operates the electric hydraulic pump. Is stopped.

Further, in the vehicle electro-hydraulic power steering apparatus according to the present invention, in addition to the above operation, when the vehicle enters a non-straight running mode in which the straight running determining unit does not determine the straight running mode, the pump control unit controls the pump. The operation of the electric hydraulic pump is immediately started by the start of the steering operation based on the information from the steering angle detecting means. Furthermore, in the electric hydraulic power steering device for a vehicle according to the third aspect, the electric hydraulic pump is operated for a predetermined time after the start by the operation holding means attached to the pump stop means, prior to the pump stop means. Held in state.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram showing an essential part of an electro-hydraulic power steering apparatus for a vehicle according to an embodiment of the present invention; FIG. 4 and 5 are graphs showing the operation characteristics, FIG. 6 is a schematic diagram showing the configuration of the data table, FIG. 7 is a graph showing the operation characteristics,
FIG. 8 is a schematic front view showing the main configuration of the steering angle sensor (steering angle detecting means), and FIG. 9 is a graph showing the operation state of the steering angle sensor (steering angle detecting means).

As shown in FIG. 1, in this embodiment, the steering mechanism 1 has, for example, a rack and pinion type steering gear 1a. Steering gear 1a
Has a rack 3 extending in the vehicle width direction in the casing 2 and a pinion gear 4 meshing with the rack 3. The pinion gear 4 is connected to the input shaft 6 of the steering gear 1a via the torsion bar 5.

Incidentally, one end of the rack 3 is connected to the left front wheel 10 via a steering rod 7, a tie rod 8, and a knuckle 9. The other end of the rack 3 includes a steering rod 11, a power cylinder device 12 as a piston mechanism, a tie rod 13, a knuckle 14
Through the front wheel 10 on the right side. On the other hand, the input shaft 6 protruding from the upper part of the casing 2 is connected to a steering joint 16 and a two-part steering shaft 17.
Through a steering wheel (steering wheel) 18.

Thus, the handle 18 is operated (rotated).
Then, the displacement is transmitted to the knuckles 9 and 14 via the steering shaft 17, the torsion bar 5, the pinion gear 4, the rack 3, and the steering rods 7 and 11, and the left and right front wheels 10 and 10 are steered in the operated direction. It has become. Reference numeral 17a denotes a steering column.

The input shaft 6 of the steering gear 1a
A rotary valve (supply / discharge valve) 19 is provided between the pinion gear 4 and the pinion gear 4. This rotary valve 19
Is formed by assembling a cylindrical outer valve 19 a connected to the pinion gear 4 and a cylindrical inner valve 19 b connected to the input shaft 6, and the torsion bar is applied by a steering force applied from the handle 18. 5
Is twisted, a relative displacement occurs between the outer valve 19a and the inner valve 19b.

The rotary valve 19 is incorporated in a hydraulic circuit 34, and is connected to the electric hydraulic pump 22 through the flow paths 21 and 24 forming the hydraulic circuit 34, thereby forming the hydraulic circuit 34. It is connected to the power cylinder device 12 via the flow paths 27a and 27b. That is, the rotary valve 19 is formed with an inflow port portion 20 and an outflow port portion 23. The inflow port portion 20 is connected to the discharge portion of the electric hydraulic pump 22 via the flow path 21, and the outflow port portion 23 is It is connected to the suction part of the electric hydraulic pump 22 via the flow path 24.

The electric hydraulic pump 22 includes a pump section 22a.
Is connected to a motor 22b driven by a battery 40, and a reservoir 2 is connected to a suction portion of the pump portion 22a.
2c is interposed. The electric motor 22b
A power supply circuit (not shown) configured by connecting a battery 40 and an alternator mounted on an automobile in parallel is connected, and the driving power of the electric motor 22b is supplied from this power supply circuit.

The pair of output ports 26a and 26b formed in the rotary valve 19 are connected to the flow path 27.
a and 27b are connected to the power cylinder device 12. The power cylinder device 12 includes a cylinder 29 fixed to a frame or the like, a piston rod 28 inserted through the cylinder 29 and having one end connected to the steering rod 11, and a vehicle fixed to the piston rod 28 and passing through the cylinder 29. It is configured as a piston mechanism having a piston 30 that partitions in the width direction.

Oil chamber 31 partitioned by piston 30
a and 31b are connected to output port portions 26a and 26b of the rotary valve 19 through a pair of input port portions 32a and 32b and flow paths 27a and 27b. That is, when the handle 18 is in the neutral state, the rotary valve 1
9, the hydraulic pressure of the electric hydraulic pump 22 is changed to the oil chambers 31a, 3
1b is supplied as neutral pressure, and when the steering wheel 18 is steered, the hydraulic pressure of the electric hydraulic pump 22 is controlled by the rotary valve 19 for the relative displacement between the outer valve 19a and the inner valve 19b and the displacement of the piston 30 in accordance with the steering. Acts as pressure on the front wheels 10,1
Zero steering is assisted.

The electric motor 2 of the electric hydraulic pump 22
A motor driver (drive circuit) 36 is provided in the power supply circuit connected to 2b.
The operation of the electric motor 22b is controlled via the. Further, a controller 37 having a pump control means 37A is connected to the motor driver 36, and the motor driver 36 is controlled by the pump control means 37A.
The operation of the electric hydraulic pump 22 is controlled through this. The controller 37 is composed of a microcomputer and its peripheral devices.

The controller 37 further includes a straight traveling determining means 37B and a traveling road mode determining means 3
7C, and the pump control means 37A is provided with a control amount setting section 37D, a pump stop means 37E, and an operation holding means 37F. The controller 37
The vehicle speed sensor 38 for detecting the traveling speed of the automobile, the steering angle sensor 39 for detecting the steering angle of the steering wheel 18 (the steering wheel angle), and the alternator L
Terminal is connected.

The pump control means 37A is activated when a "Hi" signal is output from the L terminal of the alternator,
The control amount setting unit 37D sets a control amount (motor drive command value) Mn of the electric hydraulic pump 22 based on each detection signal, and outputs a required control signal to the motor driver 36. That is, the control amount setting unit 37D, a map as shown in FIGS. 4 and 5 and is stored, using these maps, so as to set the motor drive command value Mn from the vehicle speed V and steering wheel angle theta _H Has become.

The map shown in FIG. 4 is a map for obtaining a basic motor drive command value (map command value) Mmap corresponding to the vehicle speed V. The map command value Mmap is
There the low speed range of V <V _1, have the maximum value Mmax,
In the middle speed range of V ₁ <V <V ₂ , the vehicle speed V decreases as the vehicle speed increases, and reaches a minimum value Mmin in the high speed range of V ₂ <V. This is because it is necessary to ensure the ease of steering in a low speed range, and attach importance to steering stability as the speed increases. Then, in a low-to-medium speed range (here, a speed range of less than 80 km / h) of the vehicle, the map command value Mmap is set to the motor drive command value Mn.

The map shown in FIG. 5 is for control for improving the steering neutral feeling. This control is performed in a high-speed range (here, 80 km / h) of the vehicle where the steering stability is important.
h or more). This control, steering neutral near [here, the magnitude of the steering wheel angle theta _H is in the range) within 5 deg, to increase the steering assist leave lighter to handle, steering wheel angle increases gradually performing steering in response to (in this case, the size range of 5 deg ～20Deg of the steering wheel angle theta _H), that continue to handle the heavier while decreasing the steering assist, and to provide a neutral feeling.

The map shown in FIG. 5 can be expressed by the following equation: (1) In the range of | θ _H | ≦ 5 deg, Mn = Mmax (1) (2) 5 deg <| θ _H | ≦ in the range of 20deg, Mn = Mmax - (| θ H | -5deg) × (Mmax -Mmap) / 15deg ··· (2) (3) 20deg <| θ H | in range, Mn = Mmap ··· (3) The motor drive command value Mn may be obtained by such a calculation instead of the map shown in FIG.

The straight traveling determining means 37B provided in the controller 37 determines that the steering angle detected by the steering sensor 39 is equal to or _smaller than a predetermined amount θ _H0 and within a predetermined time.
The change of the detection signal by the steering angle sensor (steering angle detecting means) 39
When the shift frequency (steering frequency) CNT ₀ is equal to or greater than a predetermined value, it is determined that the vehicle is in the straight running mode, and an information signal indicating whether the vehicle is in the straight running mode is output to the pump stopping means 37E of the pump control means 37A. It is supposed to.

The pump stopping means 37E stops the operation of the electric hydraulic pump 22 when the straight running determining means 37B determines that the vehicle is in the straight running mode and when the detected steering angle is 0 deg and no steering operation is performed. A signal for stopping the operation is output to the control amount setting unit 37D. As described above, the determination of the straight traveling mode is performed by stopping the electric hydraulic pump 22 when its output is unnecessary,
This is for the purpose of improving the fuel efficiency of the vehicle by saving electric power, while enabling the steering assist to be promptly performed when the steering operation is performed. In general,
Since the electric hydraulic pump 22 is unnecessary when the vehicle is traveling straight ahead, the straight traveling mode is determined, and in the straight traveling mode, the pump stop means 37E outputs a signal for stopping the electric hydraulic pump 22 to the control amount. It is set so as to output to the setting unit 37D, and otherwise output a signal for operating the electric hydraulic pump 22 to the control amount setting unit 37D.

Here, it is determined that the vehicle is in the straight running mode when the steering angle is equal to or _smaller than the predetermined amount θ _H0 and the steering frequency CNT ₀ is equal to or larger than the predetermined value. by. That is, when the vehicle is running straight is the steering angle theta _H is supposed to hold the 0 deg, in fact, move the handle a range of play of the steering wheel, shimmy or occurring in the handle, during rough road such as when moving the handle in order to deal with the road surface disturbance or the like to pick up the wheels etc., it is often the steering angle θ _H is other than 0deg. Thus, merely steering angle theta _H only information of the steering angle theta _H is 0de
If the electric hydraulic pump 22 is stopped only at the time of g,
The electric hydraulic pump 22 is hardly stopped, and it is difficult to realize fuel saving by stopping the operation of the electric hydraulic pump 22.

Therefore, focusing on the fluctuation characteristic of the steering angle θ _H that occurs during such straight running, the movement of the steering wheel during this straight running is generally within a small steering angle range and a certain degree. It can be said that it appears frequently. Conversely, if the steering angle θ _H is large, it can be determined that the steering operation for steering is being performed, and if the steering frequency is low, the possibility of the fluctuation of the steering angle θ _H occurring during straight running is also high. However, there is a possibility that the steering operation for steering is performed intentionally because the steering operation is specially performed, and there is a possibility that steering assist which is an original purpose of the electric hydraulic pump 22 is required.

Therefore, when the steering angle is within a small steering angle range and the steering frequency is high to some extent, it is determined that the vehicle is in the straight traveling mode. Here, the threshold value θ _{H0 of the} steering angle and the threshold value CNT ₀ of the change frequency of the steering state, which are the criteria for determining the straight traveling mode, are set according to the traveling road mode of the vehicle. Therefore, the controller 37
Is provided with a traveling road mode determination unit 37C that determines the traveling road mode of the vehicle.

The traveling road mode determination section 37C determines the vehicle speed
Average value of V_AVValue of steering angle and steering angular velocity | θ_H'|_AVRespond to
First, using the map as shown in FIG.
Are classified into city mode, curved road mode, and highway mode
It is supposed to. That is, the low vehicle speed range (the vehicle speed V is V
<V_Three), City mode M1, medium vehicle speed range (vehicle speed V is V
_Three<V <V_Four), The average value of steering angular velocity | θ_H'|_AV
Is small (| θ_H'| _AV≤θ₁) And city mode M1,
Average steering angular velocity | θ_H'|_AVIs not small (θ₁<
| Θ_H'|_AV) And curved road mode M2, high vehicle speed range (vehicle speed V
Is V_Four<V) is classified as the highway mode M3.
Also, the average value V_AVValue of steering angle and steering angular velocity | θ_H′
|_AVIs sampled for a predetermined time (for example, 5 seconds).
This is the average of the weighted values.

Then, here, in the city area mode M1
Is the threshold θ_H0Is 10deg, threshold CNT ₀Is set to 15
In the bending road mode M2, the threshold θ_H0Is 8deg, threshold C
NT₀Is set to 20, and in the highway mode M3, the threshold
θ_H0Is 5deg, threshold CNT₀Is set to 10.
Thus, in the city area mode M1, the highway mode M3
Than the threshold θ_H0, Threshold CNT₀Are set too large
However, this is because in the city mode M1, the vehicle travels straight.
Sometimes, steering angle θ is relatively large depending on road disturbance_HIn ratio
The steering wheel operation is often performed relatively frequently
It is. Also, in the curved road mode M2, the high-speed road mode
Threshold θ than M3_H0, Threshold CNT₀Are all large
However, this is straight ahead in the curved road mode M2.
When driving, responds to road disturbances in the same way as city mode M1
Relatively large steering angle θ_HMore frequently with the steering wheel
It is often done, but on the other hand, because of the original steering
Steering angle θ_HIs likely to occur, so the steering angle threshold
θ_H0Is set smaller than in the city mode M1.
I have.

By the way, such a straight traveling determining means 37B
I want to make the judgment as quickly and surely as possible. Also,
When it is determined that the vehicle is not in the straight traveling mode by the straight traveling determination means 37B, it is desired to perform steering assist as soon as the steering operation is performed. Therefore, in this device, the steering angle sensor 39 is set to have a high resolution of 1 deg unit (about three times as high as the conventional one) to speed up the generation of the steering pulse, and further,
The generated steering pulse is applied to the steering wheel 1 during straight running.
The start of steering can be detected at an early stage by making it possible to reliably identify whether or not the adjustment is based on the fine adjustment of 8.

Here, the steering angle sensor 39 is configured as shown in FIG. 8, and a disk 41 rotated by the handle 18 is provided on a steering shaft (not shown) or the like. , Slits 42 are provided at predetermined intervals. Photointerrupters 44A and 44B are provided so as to face the end faces of the outer periphery of the disk 41, and light emitted from these light emitting units is received by the light receiving unit via the slit 42, as shown in FIG. It is configured to obtain a simple pulse wave.

The photo interrupter 44A and the photo interrupter 44B are arranged at a predetermined distance from each other, and the waveform obtained is the same as the phase A and the phase B shown in FIG.
Is configured such that the positional relationship of the pulses is reversed depending on the rotation direction of the pulse. The slit 42 in the disk 41
A slit 43 indicating a neutral position is provided at a radius position different from the above, and a photo interrupter 44A corresponding to the slit 43 is also provided, so that a Z-phase waveform shown in FIG. 9 is output. That is, the Z-phase pulse is
It is configured to occur when the handle 18 passes the neutral position.

With such a configuration, a steering pulse is generated by the rotation of the disk 41, and the steering angle θ is detected. By the way, in the present embodiment, the interval between the slits 42 in the disk 41 is smaller than that of the conventional one and has a resolution of, for example, 1 deg. Thus, as compared with the conventional resolution of 3 deg. Even when the steering angle is slightly changed, a steering pulse is generated, so that early detection of the start of steering is reliably performed.

Note that the operation holding means 37F gives priority to the signal from the pump stop means 37E for a predetermined time (for example, 5 seconds) after the start of the electric hydraulic pump 22, and the operation signal of the electric hydraulic pump 22 is given. Is output. Specifically, it is configured to add the timer count value T _H by the time interval INT for each processing cycle and output an activation signal until a predetermined time is reached.

Therefore, the operation state of the electric hydraulic pump 22 is maintained for a predetermined time after steering, and the electric hydraulic pump 2
It is configured such that durability can be ensured while suppressing an increase in the on / off frequency of the second. Since the vehicular electro-hydraulic power steering apparatus as one embodiment of the present invention is configured as described above, it operates, for example, as shown in FIG.

As shown in FIG. 2, when the ignition key switch is turned on, a "Hi" signal is output from the L terminal of the alternator, and the pump control means 37A of the controller 37 is activated upon receiving this signal. I do. Then, in step S1, an initial value of an address corresponding to each flag and variable is set. That is,
The steering flag SFLG, the holding timer T _H , the straight running mode flag TFLG, the memory counter MCNT, the data table DT (MCNT), and the counter CNT are each set to “0”.

Thereafter, at step S2, the vehicle speed V output from the vehicle speed sensor 38 is read, and at step S2
At 3, the steering pulse is read from the steering angle sensor 39. At this time, a steering pulse is generated as shown in FIG. 9, the neutralization of the steering angle θ is detected by the Z phase, and the displacement from the neutral position of the steering angle θ is determined by the correlation between the Z phase and the A and B phases. That is, the magnitude | θ | of the steering angle is measured.
At this time, the increase or decrease (that is, the steering direction) of the steering angle θ is measured from the combination of the generation state of the A-phase pulse and the B-phase pulse.

Incidentally, the steering angle sensor 3 in this embodiment is
9 has a resolution about three times that of the conventional art, so that the steering pulse is also generated when the driver finely adjusts the steering wheel 18 during straight running. With respect to such a steering pulse, a steering pulse at the time of fine adjustment performed during straight traveling and a steering pulse at the time of steering are identified by the straight traveling determining means 37B described later.

Next, in step S4, the straight running mode flag TFLG set in the straight running mode determination routine SUB-ST shown in FIG. 3 is read.
Then, in step S5, it is determined whether or not there has been a change in the steering pulse. If the steering operation has not been performed, a "NO" route is taken and step S6 is executed.

At step S6, it is determined whether or not the steering flag SFLG is "1". As will be described later, the steering flag SFLG determines whether the original steering operation (that is,
The value is "1" when a steering operation is performed when the vehicle is not traveling straight, and is "0" immediately after the start of control. Therefore, the process proceeds to step S7 via the "NO" route. In step S7, the electric motor 22 is controlled by the pump stopping means 37E.
The stop state of b is continued, and the processing state returns to step S2 while the power steering apparatus is in the non-assisting state.

From step S2 to step S7
Is repeated, but if the steering operation is performed, the steering pulse read in step S3 changes from the previous state, so it is determined in step S5 that the steering pulse has changed, and "YE" is determined.
Take the "S" route to step S11. Step S
At 11, it is determined whether the straight traveling mode flag TFLG read at step S4 is "1".
The straight running mode flag TFLG becomes “1” when it is determined that the vehicle is in the straight traveling mode in the straight running mode determination routine SUB-ST, and becomes “0” when it is determined that the vehicle is not in the straight running mode. Become.

Straight running mode determination routine SUB-ST
In step S11, if it is determined that the vehicle is in the straight traveling mode and the straight traveling mode flag TFLG is "1", the "YES" route is taken in step S11, and the steps S6 and S7 are executed. Is continued. That is, the stopped state of the electric motor 22b is continued.

On the other hand, the straight traveling mode determination routine SUB
If it is determined in -ST that the vehicle is not in the straight traveling mode and the straight traveling mode flag TFLG is "0", a "NO" route is taken and steps S12 and S13 are executed. In step S12, it is determined that the original steering operation, that is, the steering operation in a state where the vehicle is not in the straight traveling state, is performed, and the steering flag SFLG is set to “0”.
To “1”.

In step S13, the holding timer T
_H is reset to "0". This holding timer _TH is
The operation holding means 37F counts the time so that the electric hydraulic pump 22 holds the operation for a predetermined time after the start. Next, in each of the steps S14 to S20, the motor drive command value Mn is set by the control amount setting unit 37D.

That is, in step S14, it is determined whether the speed V of the vehicle exceeds 80 km / h.
If the vehicle speed V is lower than 80 km / h, step S15 is executed, and FIG.
The map command value Mmap obtained from the map shown in FIG.

That is, the graph of FIG. 4 shows the motor drive command value Mn of the electric hydraulic pump 22 corresponding to the vehicle speed V. In the electric hydraulic pump 22, the oil flow rate corresponding to the motor drive state (that is, the operating oil pressure) Therefore, a motor drive command value Mn is set such that an oil flow rate can be obtained corresponding to the vehicle speed V at that time. Then, step S2
In step 1, the motor drive command value Mn set in step S15 is output to the motor driver 36, and the assist state in the power cylinder device 12 is realized according to the vehicle speed.

At this time, the motor driver 36
The operation duty ratio of the electric motor 22b is increased or decreased according to the motor drive command value Mn, and the electric hydraulic pump 22 discharges a desired flow rate. If the vehicle speed V is equal to or higher than 80 km / h, a "YES" route is taken in step S14, and steps S16 to S20 are executed.

In steps S16 to S20, the high-speed range of the vehicle (80 km /
h or more), to improve the steering neutral feeling,
Set the motor drive command value Mn. In this flowchart, the values are set in accordance with the magnitude | θ _H | of the steering angle by calculation using the above-described equations (1) to (3). That is, in step S16, the absolute value | θ _H | of the steering angle θ _H detected by the steering pulse from the steering angle sensor 39 is 5 de.
It is determined whether it is greater than or equal to g.

If | θ _H | is smaller than 5 deg, the motor drive command value Mn is set in step S17 as shown in FIG.
Is adopted as the maximum command value Mmax on the low speed side. On the other hand, when | θ _H | is larger than 5 deg, first, in step S18, the map command value Mmap corresponding to the vehicle speed V is set as the motor drive command value Mn in the map of FIG.

Further, in step S19, the steering angle θ
It is determined whether or not the absolute value of is not less than 20 deg.
When | θ _H | is smaller than 20 deg, | θ _H | is 5 de.
g to 20 deg, and in step S20,
The motor drive command value Mn is set by the above equation (2), and the motor drive command value Mn is adopted.

On the other hand, if | θ _H | is equal to or greater than 20 deg, the "YES" route is taken and the motor drive command value Mn (= map command value Mma) set in step S18 is taken.
p) is adopted as it is. Then, in step S21, as described above, step S17 or step S
18 or the motor drive command value Mn set in step S21 is output to the motor driver 36, and the assist state in the power cylinder device 12 is realized according to the vehicle speed.

At this time, the motor driver 36
Adjusts the operating duty ratio of the electric motor 22b according to the motor drive command value Mn, and the electric hydraulic pump 22 discharges a desired flow rate. Instead of the processing in steps S16 to S20, the motor drive command value M is determined based on the magnitude | θ _H | of the steering angle using the map shown in FIG.
n may be set.

In any case, as shown in the map of FIG. 5, in the vicinity of neutral steering (the range where | θ _H | is within 5 degrees),
Increase the steering assist to make the steering wheel lighter, and reduce the steering assist while | θ _H | is in the range of 5 deg to 20 deg so that the steering angle increases from the neutral position. By doing so,
A neutral feeling can be given to the driver holding the handle 18.

In order to give a neutral feeling, the motor drive command value Mn may be controlled between Mmap and Mmin. That is, in the vicinity of neutral, the motor drive command value M
Assuming that n is Mmap, the motor drive command value Mn is gradually reduced to Mmin as the steering angle increases from near neutral. On the other hand, when the steering flag SFLG is set to “1” in step S12, in the subsequent control cycle, when the steering pulse does not change and the process proceeds from step S5 to step S6, or when the steering pulse changes but the vehicle travels straight. When the process proceeds from step S5 to step S6 via step S11 in the mode, the process of steps S8 to S10 is performed by the operation holding unit 37F through the "YES" route from step S6.

[0067] That is, in step S8, is added to the predetermined time interval INT to the holding timer T _H, to hold timer T _H is reset in step S13, for each repetition of the processing cycle, time interval INT is added To go. Thus, it is determined whether the hold timer T _H obtained by adding the time interval INT has reached the predetermined time (5 seconds) at step S9, if not time reaches take "NO" route in step S9 Then, the process returns to step S2. Even if the straight running state continues, step S2
To step S11, step S6, step S8, and step S9 are repeated.

Thus, during this period, even if the steering pulse does not change or if the vehicle is in the straight running mode, step S
7 is not executed, and the assist state in the power steering device is continued. When the hold timer T _H reaches five seconds or longer, take the "YES" route in step S9, step S10 is executed steering flag SFLG is reset to "0", the motor is stopped is performed at step S7 Then, the assist state in the power steering device is stopped.

Such steps S2 to S21
The drive of the electric hydraulic pump 22 is controlled while repeating the processing of. By the way, the straight running mode flag TFLG used for the above control is set as a result of the straight running mode determination of the vehicle by the straight running mode determination routine SUB-ST.

This straight traveling mode determination routine SUB-
The ST is configured, for example, as shown in the flowchart of FIG. 3, and repeatedly performs such processing periodically at predetermined time intervals (for example, 5 ms) to determine the straight traveling mode of the vehicle. Here, such a process for every predetermined time (for example, 5 ms) is performed 1024 times, and the number of times of steering is counted from the latest 1024 process data from the present time, and this count value (steering pulse change counter) CNT is calculated. The straight running mode of the vehicle is determined from the current steering angle magnitude | θ _H |.

In this case, the steering pulse change counter CNT indicates the steering frequency, and the data sampling of 1024 times takes approximately 5 seconds (≒ 5 ms × 1024).
Data sampling. First, when the vehicle is started, as shown in FIG.
Memory counter M which is each variable used in UB-ST
The CNT, the data table DT (MCNT), the steering pulse change counter CNT, and the straight running mode flag TFLG are each initially set to “0”.

Then, as shown in FIG. 3, at the time of executing the first routine, the memory counter MCNT is set to step A1.
, "1" is added to change "0" to "1".
Next, in step A2, the memory counter MCN
It is determined whether T is greater than “1024”, and immediately after the start of the routine, the memory counter MCNT is set to “10”.
24 ", so take the" NO "route,
It reaches step A4.

In step A4, it is determined whether or not the steering pulse has changed, and if steering is not performed,
The process proceeds to Step A5 through the “NO” route. Step A
At 5, it is determined whether the data table DT (MCNT) corresponding to the memory counter MCNT is "0". This data table DT (MCNT) corresponds to “1” to “1024” of the memory counter MCNT,
Either 0 or 1 is written to each of 1024 addresses DT (1) to DT (1024). At the start of the control routine, DT (1) to DT (DT)
(1024) are initially set to 0.

Therefore, in the state immediately after the start of the routine, DT (1) is "0", the route "YES" is taken, and the process of steps A6 and A7, which are the "NO" route, is not carried out, and step A11 is executed. Leads to.
On the other hand, if steering is being performed, from step A4,
The process proceeds to step A8 through the "YES" route.

At step A8, the memory counter MCN
Data table DT (MCNT) corresponding to T is "0"
Is determined. In the state immediately after the start of the routine, DT (1) is "0", and the "YES" route is taken, the process proceeds to step A9, and 1 is added to the steering pulse change counter CNT. Immediately after the start of the routine, since CNT is initially 0, CNT becomes 1 by this addition.
Then, the process proceeds to step A10, where the data table DT
(MCNT) is rewritten to 1. 1 immediately after the start of the routine
In the case of the third processing, DT (1) is rewritten to 1. Then, the process reaches step A11.

In step A11, the steering wheel angle θ _H is calculated based on the output signals from the sensors, and in step A12
Is executed. In the following step A12, it is determined from the determination information in the travel road mode determination unit 37C whether the travel road mode is the city area mode, the curved road mode, or the highway mode. Although the operation of the traveling road mode determination unit 37C is not specifically shown, the average vehicle speed V _AV
The travel road mode is determined using a map as shown in FIG. 7 according to the average value of steering angular velocity | θ _H ′ | _AV .

Then, it is determined whether or not the vehicle is in the straight traveling mode according to each traveling road mode. That is, in the city area mode M1, Step A13 to Step A1
It is determined in the process of 6 whether or not the vehicle is in the straight traveling mode,
In the case of the curved road mode M2, it is determined whether or not the vehicle is in the straight traveling mode in the processing in steps A17 to A20.
In the process of step A24, it is determined whether or not the vehicle is in the straight traveling mode.

In each mode, since only the threshold value for the straight traveling judgment is different, the processing in the case of the highway mode M3 will be described. In step A21, the magnitude of the steering wheel angle | θ
_H | is determined whether is more than 5 deg, the magnitude of the steering wheel angle | theta _H | is be not less than 5 deg, "NO"
Step A22 is executed through the route. Step A
At 22, it is determined whether or not the counter CNT is smaller than “10”. In the first process, if the steering operation is not performed, the counter CNT is “0”, and the steering operation is performed. For example, the counter CNT is "1", and in each case, the "NO" route is taken, and in step A23, the straight traveling mode flag TFLG = "1".
Is performed.

Thus, the first processing of the straight traveling mode determination routine SUB-ST is completed. Next, the second and subsequent processes are performed at predetermined time intervals (5 ms). Every time this process is performed, the memory counter MCNT in step A1 is incremented by "1", and until it becomes larger than "1024" in step A2.
That is, the memory counter MCNT changes from “1” to “102”.
1024 processes up to "4" are performed.

In the meantime, in steps A5 to A9, the data table DT (MCNT) corresponding to the value of each memory counter MCNT is updated, and
The counter CNT is also updated. For example, if a change occurs in the steering pulse when a certain memory counter MCNT = “X”, the process proceeds from step A4 to step A8. If the corresponding previous data table DT (X) is 0, the counter CNT is set in step A9. Is increased by 1 and the data table DT (X) is newly changed to 1 in step A10. If the corresponding previous data table DT (X) is 1, the counter CNT does not change and the data table DT (X) is already 1, so that the processing of steps A9 and A10 is performed. Absent.

On the other hand, a certain memory counter MCNT =
If there is no change in the steering pulse at the time of "X", the process proceeds from step A4 to step A5. If the corresponding previous data table DT (X) is 0, the counter CNT is set.
Does not change, and the data table DT (X) is already 0
Are not changed. If the corresponding previous data table DT (X) is 1, the counter CNT is decremented by 1 in step A6, and step A7 is executed.
To newly change the data table DT (X) to 0.

As a result, the steering pulse change counter CNT is always included in the latest 1024 sampling data.
Will be counted. This operation will be specifically described with reference to the schematic diagram shown in FIG. In FIG. 6,
Those with DT (MCNT) of 0 are partially omitted. FIG.
As shown in FIG. 2, "1024" memories are secured as the data table DT (MCNT).
If there is a change in the steering pulse when CNT = “3”, “1” is written to DT (3) in step A10.
Thus, the counter CNT becomes “1”.

If there is a change in the steering pulse in the i-th examination in which MCNT = “i”, step A10
In step (1), "1" is written to DT (i). Thus, the counter CNT becomes “2”. Also, MCNT =
Similarly, for “i + 1” and “i + 3”, DT (i
+1) = “1”, DT (i + 3) = “1”, and in each case, the counter CNT = “3”, “4”, and there are four steering pulse changes from the beginning to the “i + 3” time. It is shown that.

Further, the “1022” time, “1024”
If there is a change in the steering pulse at each time, each data table DT (MCNT) is rewritten, and the counter CNT becomes "5", "6". Thus, in the first "1024" steering pulse change study, there are "6" steering pulse changes.

Further, in each of these memories, the presence or absence of the last "1024" steering pulse changes is "0",
It is stored as one of “1”. After such “1024” studies, MCNT = “102”
Therefore, in step A2, the "YES" route is taken, and in step A3, MCNT = "1", and the memory counter MCNT is reset.

Thus, the subsequent memory counter MC
The check of NT is performed for the corresponding address from the previous MCNT = "1". Therefore, when it is determined that there is no change in the steering pulse for the memory counter MCNT = “3”, DT (3) is set to “1” last time.
On the other hand, since this time is "0", the counter CNT is reduced by "1" in step A6, and DT (3) is rewritten to "0" in step A7.

As a result, the counter CNT = 5,
While the counter CNT = 6 during the “1024” data from the previous memory counter MCNT = “3” to the current memory counter MCNT = “2”,
After the steering pulse change for the memory counter MCNT = 3 is checked, the previous memory counter MCNT
= “4” to “1024” data from the current memory counter MCNT = “3”, the counter CNT
= 5, indicating that the steering pulse has changed five times from the present time to the time before “1024” data.

Further, the memory counter MCNT = “j”
When it is determined that there is a change in the steering pulse, DT (j) is “1” this time, whereas DT (j) was “0” last time.
NT is incremented by “1”, and the counter CNT becomes “6”, indicating that the steering pulse has changed six times from this time to before “1024” data. And
In step A10, DT (j) is rewritten to "1".

Further, the memory counter MCNT = “i”
If there is no change in the steering pulse at the time, since the state is different from the previous time, DT (i) is rewritten from “1” to DT (i) = “0”, the counter CNT is reduced by “1”, and the counter CNT = “1”. 5 ", indicating that the steering pulse has changed five times from this time to the time before" 1024 "data.

As described above, “10” before the current time point
In the data of the "24" times, the number of times the steering pulse change has occurred is determined by the straight running mode determination routine SUB-S.
T is detected at each execution timing of T, and determination data as to whether or not the vehicle is in the straight running mode is constantly calculated.
Then, for each traveling road mode, in steps A13 and A14, steps A17 and A18, or steps A21 and A22,
It is determined whether the traveling state of the vehicle is in the straight traveling mode. If the vehicle is in the straight traveling mode, the straight traveling mode flag TFLG is set to "1". If not, the straight traveling mode is set. Flag TFLG = "0"
Is set to

That is, the traveling road mode is the city mode M
In the case of 1, in step A13, the magnitude of the steering wheel angle |
It is determined whether θ _H | is equal to or greater than 10 deg, and | θ
_{If H} | is steered by 10 degrees or more, it is determined that a clear steering operation has been performed, not the state of fine adjustment of the steering wheel during straight running, and the process proceeds to step A16 via the "YES" route to go straight. The traveling mode flag TFLG is set to “0” which is not the straight traveling mode.

On the other hand, if it is determined in step A13 that the steering wheel angle magnitude | θ _H | is not greater than 10 deg, the steering wheel is within the fine adjustment and satisfies one of the conditions in the straight running mode. , The steering frequency determination process in step A14 is performed. In this step A14, the past 1024
Steering pulse change counter C obtained by sampling twice
It is determined whether or not the value of NT is smaller than "15", and whether or not the vehicle is traveling straight ahead is determined based on the magnitude of the determination.

When the value of the counter CNT is smaller than "15", the change in the steering pulse is small as a whole.
As the possibility of the steering operation is high, the process proceeds to step A16 through the "YES" route, and the straight traveling mode flag TFLG is set to "0" which is not the straight traveling mode. On the other hand, if the value of the counter CNT is larger than “15”, the steering is frequently performed at a small angle, and it is assumed that the steering wheel is being finely adjusted during straight-ahead traveling, and the process proceeds to step A15 through the “NO” route. Proceed to
The straight running mode flag TFLG is set to “1” which is the straight running mode.

When the traveling road mode is the curved road mode M2, the magnitude of the steering wheel angle | θ _H is determined in step A17.
Is greater than or equal to 8 deg. If steering is performed with | θ _H | being greater than or equal to 8 deg, it is assumed that an obvious steering operation has been performed instead of the fine adjustment of the steering wheel during straight running. Through the "YES" route to step A20, where the straight traveling mode flag TFLG is set.
Is set to “0” which is not the straight running mode.

On the other hand, if it is determined in step A17 that the magnitude of the steering wheel angle | θ _H | is not greater than 8 deg, the steering wheel is within the fine adjustment and satisfies one of the conditions of the straight running mode, so the “NO” route , The steering frequency determination process of step A18 is performed. That is,
In step A18, it is determined whether or not the value of the steering pulse change counter CNT obtained in the past 1024 samplings by the means described above is smaller than "20". Is done.

If the value of the counter CNT is smaller than "20", the change in the steering pulse is small as a whole.
As the possibility of the steering operation is high, the process proceeds to step A20 via the "YES" route, and the straight traveling mode flag TFLG is set to "0" which is not the straight traveling mode. On the other hand, if the value of the counter CNT is larger than “20”, the steering is frequently performed at a minute angle, and it is determined that the steering wheel is being finely adjusted during straight-ahead traveling, and the “NO” route is taken through step A19. Proceed to
The straight running mode flag TFLG is set to “1” which is the straight running mode.

Further, the traveling road mode is the high-speed road mode M3.
In step A21, the magnitude of the steering wheel angle | θ
It is determined whether or not _H | is 5 deg or more, and | θ _H |
When steering is performed for 5 deg or more, it is determined that a clear steering operation has been performed instead of the steering wheel fine adjustment state when traveling straight ahead,
Proceeding to step A24, the straight traveling mode flag TFL
G is set to “0” which is not the straight running mode.

On the other hand, if it is determined in step A21 that the magnitude of the steering wheel angle | θ _H | is not more than 5 deg, the steering wheel is within the fine adjustment and satisfies one of the conditions of the straight running mode, so the “NO” route , The process proceeds to step A22, and the steering frequency determination process in step A13 is performed. That is, in step A22, the value of the steering pulse change counter CNT obtained in the past 1024 samplings by the above-described means is set to “1”.
It is determined whether it is smaller than "0", and whether or not the vehicle is traveling straight ahead is determined based on the magnitude.

When the value of the counter CNT is smaller than “10”, the change in the steering pulse is small as a whole.
Since the possibility of the steering operation is high, the process proceeds to step A24 through the "YES" route, and the straight traveling mode flag TFLG is set to "0" which is not the straight traveling mode. On the other hand, if the value of the counter CNT is larger than "10", the steering is frequently performed at a small angle, and it is determined that the steering wheel is being finely adjusted when the vehicle is traveling straight ahead. Proceed to
The straight running mode flag TFLG is set to “1” which is the straight running mode.

As described above, the straight traveling mode flag TFL
The value of G is captured in step S4 of the flowchart shown in FIG. 2, and the straight traveling mode determination routine SUB-
The determination result of the straight running in ST is reflected in a predetermined state in the assist state of the power steering device. That is, when the vehicle that does not require assistance in the power steering device is in the straight running mode, the electric hydraulic pump 22 stops, and the energy used for the operation of the electric hydraulic pump 22 is reduced.

In particular, even when the vehicle is traveling straight, a steering pulse is frequently generated in a traveling state in which a fine steering adjustment is performed. It is determined by the routine SUB-ST whether or not the vehicle is in the straight traveling mode. If the vehicle is in the straight traveling mode, the electric hydraulic pump 22 stops even if a steering pulse is generated. The effect of saving is large.

Accordingly, malfunction of the motor on / off operation due to rough road running, road surface disturbance, and shimmy vibration of the steering wheel is prevented, and the resolution of the steering angle sensor 39 for generating a steering pulse is improved as in this embodiment. When the steering assist is unnecessary, the electric hydraulic pump 22 can be stopped appropriately, and an energy saving effect can be obtained. In addition, by improving the resolution of the steering angle sensor 39 that generates the steering pulse, when the vehicle is not in the straight running mode (when there is a possibility of steering), the electric hydraulic pump 22 quickly generates the steering pulse when the steering pulse is generated. Since the motor is started, the steering assist is quickly performed when necessary without causing a feeling of operation delay due to the motor start delay.

Further, as described above, once the electric hydraulic pump 22 is started, the operation of the electric hydraulic pump 22 is stopped for a predetermined time (here, 5 seconds) even if the steering is not performed and the vehicle is in the straight running mode. Will be retained. For this reason, the frequency of turning on and off the motor is reduced, the durability of the motor is improved, and hunting of control is avoided, and stable control can be performed.

In this embodiment, the determination of the straight traveling mode is changed depending on the traveling road mode. However, here, the determination of the traveling road mode is made by averaging the data for 5 seconds similarly to the determination of the straight traveling mode. It's done by value. That is,
The determination of the traveling road mode is performed based on the data at the same time as the determination of the straight traveling mode. Therefore, when the traveling road mode is changed, the data in the changed new traveling road mode is used for the determination of the straight traveling mode, and the control can be appropriately performed.

Needless to say, the reference value (threshold) for determination in each traveling road mode is not limited to that of this embodiment, but can be set to various values, and the classification of traveling road modes is not limited to this. Further, instead of changing the determination of the straight traveling mode for each traveling road mode, the determination of the straight traveling mode may be performed on all the traveling roads with a fixed threshold value.

[0106]

As described above in detail, according to the electric hydraulic power steering apparatus for a vehicle according to the first aspect, the steering mechanism for steering the steered wheels according to the operation of the steering wheel provided in the vehicle, and the electric motor. An electric hydraulic pump driven by a drive source, a piston mechanism attached to the steering mechanism to assist the steering in the steering mechanism, and the electric hydraulic pressure to supply hydraulic oil for assisting steering to the piston mechanism. A hydraulic circuit interposed between a pump and the piston mechanism, a piston mechanism provided to assist steering in the steering mechanism,
A hydraulic circuit for connecting the piston mechanism and the electric hydraulic pump, a steering angle detecting means for detecting a steering angle by the steering wheel, and controlling the operation of the electric hydraulic pump based on a detection signal from the steering angle detecting means. Pump control means, wherein the steering angle detected by the steering angle detection means is equal to or less than a predetermined amount and the steering angle detection within a predetermined time is performed.
Straight running determining means for determining that the vehicle is in the straight running mode when the change frequency of the detection signal by the output means is equal to or greater than a predetermined value; , An erroneous on / off operation of the electric hydraulic pump caused by rough road running, road surface disturbance, and shimmy vibration of the steering wheel is eliminated, and steering with high resolution is provided. Even if the angle detection means is provided, the operation frequency of the electric hydraulic pump can be suppressed, and by improving the resolution of the steering angle detection means, the steering assist from the stop state of the electric hydraulic pump is promptly started, There is an advantage that the fuel efficiency of the vehicle can be improved by stopping the electric hydraulic pump while sufficiently securing the steering assist performance.

Further, since the operation frequency of the electric hydraulic pump can be reduced, the durability of the electric motor of the pump is also improved. Also,
According to the vehicular electro-hydraulic power steering apparatus of the present invention, when the pump control means enters a non-straight running mode in which the straight running determining mode does not determine the straight running mode, it is based on information from the steering angle detecting means. Therefore, the operation of the electric hydraulic pump is started immediately upon the start of the steering operation, so that the steering assist can be quickly started from the stop state of the electric hydraulic pump, and the performance of the steering assist can be improved, and the rapid steering can be performed. There is an advantage that the steering force is surely assisted even at times.

Further, according to the electric hydraulic power steering apparatus for a vehicle according to the third aspect, the pump control means sets the electric hydraulic pump in an operating state for a predetermined time after the start thereof, prior to the pump stopping means. With the configuration in which the operation holding means for holding is provided, there is an advantage that the starting frequency of the electric hydraulic pump can be reduced and the durability of the electric hydraulic pump is improved.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a main configuration of an electric hydraulic power steering apparatus for a vehicle as one embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the vehicular electro-hydraulic power steering device as one embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of the vehicular electro-hydraulic power steering device as one embodiment of the present invention.

FIG. 4 is a graph showing operating characteristics of the vehicle electro-hydraulic power steering device as one embodiment of the present invention.

FIG. 5 is a graph showing the operation characteristics of the vehicular electro-hydraulic power steering device as one embodiment of the present invention.

FIG. 6 is a schematic diagram showing a configuration of a data table of an electric hydraulic power steering device for a vehicle as one embodiment of the present invention.

FIG. 7 is a graph showing the operation characteristics of the vehicular electro-hydraulic power steering device as one embodiment of the present invention.

FIG. 8 is a schematic front view showing a main configuration of a steering wheel angle sensor of the electric hydraulic power steering device for a vehicle as one embodiment of the present invention.

FIG. 9 is a graph showing an operation state of a steering wheel angle sensor of the electric hydraulic power steering device for a vehicle as one embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 steering mechanism 1a steering gear 2 casing 3 rack 4 pinion gear 5 torsion bar 6 input shaft 7 steering rod 8 tie rod 9 knuckle 10 front wheel 11 steering rod 12 power cylinder device as piston mechanism 13 tie rod 14 knuckle 16 steering joint 17 steering shaft 17a steering Column 18 Handle (steering wheel) 19 Rotary valve 19a Outer valve 19b Inner valve 20 Inflow port section 21 Flow path 22 Electric hydraulic pump 22a Pump section 22b Electric motor 22c Reservoir 23 Outflow port section 24 Flow path 26 Spring 26a Output port section 26b Output port Part 27 Grommet 27a Flow path 27b Flow path 28 Piston rod 29 Linda 30 Piston 31a Oil chamber 31b Oil chamber 32a Input port section 32b Input port section 34 Hydraulic circuit 36 Motor driver 37 Controller 37A Pump control means 37B Straight running determination means 37C Runway mode determination means 37D Control amount setting part 37E Pump stop means 37F Operation Holding means 38 Vehicle speed sensor 39 Steering angle sensor as steering angle detecting means 40 Battery 41 Disk 42, 43 Slit 44A, 44B, 44C Photointerrupter M1 City area mode M2 Curved road mode M3 Highway mode

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B62D 6/00

Claims (3)

(57) [Claims] 1. A steering mechanism for steering a steered wheel in response to an operation of a steering wheel provided in a vehicle; an electric hydraulic pump driven by an electric motor as a driving source; and a steering mechanism for assisting the steering in the steering mechanism. A piston mechanism attached to the mechanism, a hydraulic circuit interposed between the electric hydraulic pump and the piston mechanism to supply hydraulic fluid for assisting steering to the piston mechanism, and a steering angle by the steering wheel And a pump control means for controlling the operation of the electric hydraulic pump based on a detection signal from the steering angle detection means, wherein the steering angle detected by the steering angle detection means is equal to or less than a predetermined amount. And the detection by the steering angle detecting means within a predetermined time.
Straight running determination means for determining that the vehicle is in the straight running mode when the change frequency of the output signal is equal to or higher than a predetermined value is provided, and the pump control means determines the straight running mode by the straight running determining means. Pump stop means for stopping the operation of the electric hydraulic pump is provided,
Electric hydraulic power steering device for vehicles. 2. When the pump control means enters a non-straight running mode in which the straight running determining means does not determine the straight running mode, the electric hydraulic pump is immediately started upon starting a steering operation based on information from the steering angle detecting means. The power steering device with the control device for straight ahead according to claim 1, characterized in that the operation is started. 3. The pump control means is provided with an operation holding means for holding the electric hydraulic pump in an operating state for a predetermined time after the start thereof, prior to the pump stop means. An electric hydraulic power steering device for a vehicle according to claim 2.