JP4392763B2 - Hydraulic power steering device with handle angle correction function - Google Patents

Description

  The present invention relates to a hydraulic power steering apparatus that is provided in a traveling vehicle such as a cargo handling vehicle and transmits a steering operation of a passenger to a steering wheel.

As a traveling vehicle to which the hydraulic power steering device is applied, for example, there is a cargo handling vehicle shown in FIG. The cargo handling vehicle 1 includes drive wheels 2 driven by a motor, a handle 4, and a pair of steering wheels 3 whose steering wheel angle is controlled by the handle 4.
Further, as shown in FIG. 5B, the handle 4 includes a knob 5. Thereby, the passenger can operate a lever or the like for raising and lowering the fork with the other hand while operating the handle 4 with one hand.

FIG. 6 shows the relationship between the operation of the handle 4 by the passenger and the steered wheels 3. When the occupant rotates the handle 4 clockwise, a target steering wheel angle θ _T that is a traveling direction with respect to the vehicle body representative point P is obtained based on the handle angle θ _H , and the steering wheel angle θ of the steering wheel 3 is obtained. _W is controlled to be equal to the target steering wheel angle theta _T. As is well known, the steering wheel angle θ _W of the left and right steering wheels 3 is slightly different, but for the sake of simplicity, the steering wheel angle θ _W of the left and right steering wheels 3 is the same in this specification. To do.

Note that when the handle 4 is operated clockwise, steering wheel angle theta _H is a positive value. Hereinafter, this handle operation is referred to as “forward rotation” in the present specification. In normal rotation, the steering wheel angle theta _W of the steering wheel 3 is changed counterclockwise. The cargo handling vehicle 1 moves forward while turning clockwise. Conversely, when the handle 4 is operated counterclockwise, steering wheel angle theta _H is a negative value. Hereinafter, this handle operation is referred to as “reverse rotation” in this specification.
Further, steering wheel angle sensor for detecting a steering wheel angle theta _H (described later), the handle angle theta _{H (e.g.,} 540 °, 720 °) when the handle 4 is operated one revolution more than can be detected accurately.

A conventional hydraulic power steering apparatus provided in the cargo handling vehicle 1 is shown in FIG.
In this hydraulic power steering apparatus, the oil supply unit 10 includes a tank, a pump, and the like, and the oil in the tank is sent out at a predetermined hydraulic pressure by the pump. The hydraulic control unit 11 is directly controlled by the handle 4, and sends an amount of oil corresponding to the handle angle θ _H from the tank of the hydraulic control unit 10 to the cylinder 12. The cylinder 12 includes a piston that reciprocates in a cylindrical cylinder rod in accordance with the amount and direction of the oil that is sent, and the piston moves to change the steering wheel angle θ _W of the steering wheel 3. .

  The hydraulic lines 16 and 17 connect the hydraulic control unit 11 and the cylinder 12. When the handle 4 is operated, one line becomes a delivery line that sends oil to the cylinder 12, and the other feeds oil to the oil supply unit 10. This is the return line to send back. As shown in FIG. 7, when the operation of the handle 4 is forward rotation, the hydraulic line 16 becomes a delivery line and the hydraulic line 17 becomes a return line.

Incidentally, in the hydraulic power steering apparatus, an oil leak or the like of the hydraulic control unit 11 is deviation occurs in the oil quantity of relationships to be sent to the steering wheel angle theta _H and the cylinder 12 due Thus, the target steering wheel angle theta _T error in the relationship between the steering wheel angle θ _W there is a risk that occurs when.
If an error occurs, the passenger cannot rely on the position of the knob 5 to steer the cargo handling vehicle 1, and the operability is significantly deteriorated, and there is a problem in terms of safety.

Therefore, conventionally, a hydraulic power steering device that can correct the error by the flow means 13 and the handle angle correction unit 20 ′ shown in FIG. 8 has been studied (see, for example, Patent Document 1). The flow means 13 is, for example, a valve.
The hydraulic power steering apparatus includes a steering wheel angle theta _H and the steering wheel angle theta _W are monitored by the handle angle correction unit 20 ', the valve 13 is opened when it is determined that an error has occurred. When the valve 13 is opened, oil in the hydraulic lines 16 and 17 can flow through each other, and oil is not supplied to the cylinder 12. In other words, while the valve 13 is open, the steering wheel angle theta _W even if the handle 4 does not change. Hereinafter, this state is referred to as “idling”.

An example of the operation of the valve 13 and the handle angle correction unit 20 ′ is shown in FIG. 9A is a graph when the steering direction of the handle 4 is changed at a relatively slow cycle (for example, 10 seconds). The upper graph in FIG. 9A shows the steering wheel angle θ _W detected by the steering wheel angle sensor 15 and the target steering wheel angle θ _T obtained from the steering wheel angle θ _H. The middle graph shows the angle error θ _err calculated by the expression “θ _T −θ _W ”. Also, lower graph, a valve control signal S _B outputted from the steering wheel angle correction unit 20 'to the valve 13.

When the occupant rotates the handle 4 forward at time t _{1 to} t ₂ , the target steering wheel angle θ _T changes from 0 to 20 ° accordingly. At this time, the steering wheel angle θ _W should change from 0 ° to 20 ° following the target steering wheel angle θ _T , but only 10 ° has changed due to an oil leak inside the hydraulic control unit 11. Therefore, the angle error θ _{err at} time t ₂ is 10 °.

At time t _2, when the passenger changes to reverse the steering direction from the normal rotation, the angle error theta _err with a predetermined threshold value theta _THP, is compared with _{the THN} performed by the handle angle correction unit 20 '. The threshold _values θ _{THP and THN} are + 5 ° and −5 °, respectively. At time _{t 2,} the angle error theta _err is above the threshold theta _THP. Therefore, it is determined that an unacceptable error has occurred, the valve 13 is opened, and the handle 4 is idling.

As is apparent from FIG. 9A, the angle error θ _err is corrected and decreased during idling. When the angle error θ _err falls below the threshold θ _THP , the valve 13 is closed. Thereafter, the steering wheel angle θ _W changes following the target steering wheel angle θ _T while maintaining an allowable range error (5 °).
JP 61-261164 A

However, steering wheel angle correction unit 20 'from the output of the valve control signal S _B for opening and closing the valve 13, by the actual valve 13 is opened and closed, the delay time of about normal number m~500m seconds occurs. For this reason, if the steering direction of the handle 4 is changed at a relatively fast cycle (for example, 400 msec) in the conventional hydraulic power steering apparatus, there will be a problem in the case of a slow cycle as shown in FIG. Due to the delay time that was not present, the error sometimes increased each time correction was performed.

This is shown in the graph of FIG.
As in the case of FIG. 9A, the angle error θ _err at time t ₂ in FIG. 9B is 10 °. When the occupant changes the steering direction from normal rotation to reverse rotation at time t ₂ , it is determined that an unacceptable error has occurred by comparing the angle error θ _err with the threshold value θ _THP and the valve 13 is opened. control signal _{S B} is output. However, the valve 13 is not opened immediately, open to the time _{t 3} when _the delay time _{T on} has elapsed.

When the valve 13 is actually opened, the handle 4 is idled and the angle error θ _err is corrected. Then, it is the time _{t 4,} the angle error theta _err when falls below the threshold value theta _THP valve control signal for closing the valve 13 _{S B} is output. However, the valve 13 is not closed immediately, keep flow through the oil even after the steering direction at the time t ₅ is switched to the forward rotation. Then, the valve 13 is closed finally at time _{t 6} the delay time _{T off} has elapsed from the time _{t 4.}

Eventually, the angle error θ _err is once corrected within the allowable range at time t ₄ , but then deteriorates again. Then, the angle error θ _err after correction at time t ₆ is larger than the angle error θ _err before correction at time t ₃ . Similarly, in the correction between the times t _{7 and} t ₈ and the correction between the times t _{9 and} t ₁₀ , the angle error θ _err is worsened by the correction.

As described above, in the conventional hydraulic power steering apparatus, when the steering direction is repeatedly changed at a relatively fast cycle, the angle error θ _err increases every time correction is performed by the valve 13. The problem when an error occurs is as described above.

Therefore, according to the present invention, when the steering direction is changed at a relatively slow cycle, the conventional angle error θ _err can be corrected, and even when the steering direction is changed at a relatively fast cycle. It is an object of the present invention to provide a hydraulic power steering device in which the angle error θ _err does not deteriorate.

In order to solve the above-described problems, a hydraulic power steering apparatus according to the present invention includes:
A handle, a hydraulic control unit connected to the handle, a cylinder for controlling an angle θ _W of a steered wheel, and a set of hydraulic lines for connecting the hydraulic control unit and the cylinder, and an angle θ of the handle An amount of oil corresponding to _H is sent to the cylinder through one of the hydraulic lines, and sent back to the hydraulic control unit through the other hydraulic line, thereby transmitting the operation of the handle to the steered wheels. I) hydraulic power steering, i) when a control signal is input, the oil in the one hydraulic line is caused to flow through the other hydraulic line, and the oil to be sent to the cylinder is supplied to the hydraulic control unit. and flowing means for sending back, ii) a handle angle sensor for detecting the angle theta _H of the handle, iii) a steering wheel for detecting the angle theta _W of the steering wheel And degree sensor, iv) based on the angle theta _H of the handle, and the target steering wheel angle calculating unit for obtaining the target steering wheel angle theta _T, v) errors for obtaining the angle error theta _err by formula _{"θ T} -θ _W" a calculation unit, vi) based on the angle theta _H of the handle, the steering direction of the steering wheel and the steering direction determination unit for determining whether a reverse or a forward, vii) obtained by the error calculator Referring to the angle error θ _err and the steering direction determined by the steering direction determination unit, the angle error θ _err is larger than a first threshold and the steering direction is reverse, or the angle error θ _{if err} is small and the steering direction than the second threshold condition is a normal rotation continues for a predetermined time, the control signal output to the flowing means flows means control unit for flow through the oil And the predetermined time Is preset in the range of 10 m to 500 msec, which is an assumed half-cycle of the steering direction change .

  Preferably, the first threshold value is 1 to 10 °, and the second threshold value is −1 to −10 °.

  In order to solve the above problems, a traveling vehicle according to the present invention includes the hydraulic power steering device.

According to the present invention, since the correction by the valve is performed only when the steering direction is not changed for a predetermined time, the angle error θ _err is deteriorated even when the steering direction is changed at a relatively fast cycle. It is possible to provide a hydraulic power steering device without any problems. In addition, according to the present invention, it is possible to provide a hydraulic power steering apparatus that can correct the conventional angle error θ _err when the steering direction is changed at a relatively slow cycle.

  Hereinafter, a preferred embodiment of a hydraulic power steering apparatus according to the present invention will be described with reference to the accompanying drawings. In the following description, a hydraulic power steering device applied to the cargo handling vehicle shown in FIG. 5 will be described as an example of a traveling vehicle.

FIG. 1 is a block diagram of a hydraulic power steering apparatus according to the present invention.
The hydraulic control unit 11 is directly controlled by the handle 4, and sends an amount of oil corresponding to the handle angle θ _H to the cylinder 12 out of the oil sent from the tank of the oil supply unit 10. Cylinder 12 is connected to a pair of steered wheels 3, depending on the amount and direction of the incoming oil, to vary the steering wheel angle theta _W of the steering wheel 3.
The hydraulic lines 16 and 17 connect the hydraulic control unit 11 and the cylinder 12, and when the handle 4 is operated, one line becomes a delivery line that sends oil to the cylinder 12, and the other feeds oil to the oil supply unit 10. This is the return line to send back. As shown in FIG. 1, when the operation of the handle 4 is forward rotation, the hydraulic line 16 becomes a delivery line and the hydraulic line 17 becomes a return line.

Steering wheel angle sensor 14 is provided in the vicinity of the handle 4, it converts the sensed steering wheel angle theta _H in a suitable electrical signal. As described above, the handle angle sensor 14 can detect the steering wheel angle theta _H exceeding 360 °. Further, a steering wheel angle sensor 15 is provided near the steering wheel 3, it converts the steering wheel angle theta _W has been detected in an appropriate electrical signal.

The hydraulic power steering apparatus shown in FIG. 1 further includes a valve 13 that is a flow means and a handle angle correction unit 20 that controls opening and closing thereof. Oil allows Tsuryu mutually between the hydraulic line 16 and 17 when the valve 13 by the valve control signal S _B outputted from the steering wheel angle correction unit 20 is opened, the handle 4 is idles.

Target steering wheel angle calculating unit 21 provided in the steering wheel angle correction unit 20, based on the information such as vehicle size stored with the handle angle theta _H in the storage unit 22, the target steering a traveling direction of the vehicle body representative point the calculation of wheel angle θ _T. The error calculator 23 calculates an angle error θ _err (= θ _T −θ _W ) based on the steering wheel angle θ _W and the target steering wheel angle θ _T. Steering direction determination unit 25 outputs a steering direction signal S _H based on steering wheel angle theta _H. According to the steering direction signal S _H, it can be steered direction or a forward, identifying whether it is reversed. The timer 26 has a function like a stopwatch, and measures the time (hereinafter referred to as timer time) from when a start instruction is given until a reset instruction is given. Also, flowing means control unit 24, the angular error theta _err, and steering direction signal S _H, referring to the timer time. Then, it alters the valve control signal S _B when a predetermined condition is satisfied, to open and close the valve 13.

  Next, the operation of the handle angle correction function in the hydraulic power steering apparatus according to the present invention will be described with reference to the flowchart shown in FIG. 2 and the example of the operation graph shown in FIG.

When traveling of the cargo handling vehicle starts, first, the valve 13 is turned OFF as an initialization operation, and a reset instruction is given to the timer 26 (step S1 in FIG. 2). If the traveling of the cargo handling vehicle is not stopped (“No” in Step S2), the steering wheel angle θ _H and the steering wheel angle θ _W are input to the steering wheel angle correction unit 20 (Step S3). Then, the target steering wheel angle calculator 21 calculates the target steering wheel angle θ _T (step S4), and the error calculator 23 calculates the angle error θ _err from the target steering wheel angle θ _T and the steering wheel angle θ _W. (Step S5).

Thereafter, the flow means control unit 24 compares the angle error θ _err with the threshold value θ _THN (step S6), and then compares the angle error θ _err with the threshold value θ _THP (step S7). In the present embodiment, the threshold _values θ _{THP and THN} are + 5 ° and −5 °, respectively, but are free within a range that does not hinder the passenger's steering wheel operation (eg, 1 to 10 °, −1 to −10 °). Can be determined. If neither of the conditions of steps S6 and S7 is satisfied, that is, if the angle error θ _err is within the allowable range, the initialization operation of step S8 is performed, and the process returns to step S2.
At times t _{1 to} t ₂ in FIG. 3, the above steps S2 to S8 are repeatedly executed. In addition, you may perform step S6 and S7, changing order.

Since the angle error θ _err exceeds the threshold θ _THP after the time t ₂ , it is determined whether or not the condition of step S7 is satisfied and the steering direction is reverse (step S9). This determination is made based on the steering direction signal S _H. Steering direction of the time _t 2 ~t ₃ is so forward, not satisfy the condition in step S9, the initialization of the timer 26 is performed (step S10). Then, until the steering direction at the time _{t 3} is changed to reverse, step S2~S10 is repeatedly executed.

When the steering direction at the time t ₃ is changed to reverse, it satisfies the condition of step S9, the timer time "0" is determined whether or not exceeded is performed (step S13). Immediately after the steering direction is changed to reverse rotation, the timer 26 has not yet started, so the timer time is “0”. Therefore, the start instruction is given to the timer 26 from the flow means controller 24 (step S14), and the process returns to step S2. Then, when step S13 is executed again, since the timer 26 has already been started, it is determined that the timer time exceeds “0”.

Subsequently, it is determined whether or not the timer time exceeds a predetermined time _Tc (step S15). The predetermined time _Tc is, for example, 250 milliseconds. The predetermined time _Tc is preferably set to about ½ of the assumed quick steering direction change cycle, and is set in the range of, for example, 10 m to 500 msec. During the steering direction is to the time t ₄ when the change in the forward, step S2~S15 is repeatedly executed. Then, at time _{t 4,} no longer satisfy the condition of the step S9, the reset instruction is issued to the timer 26 (step S10).
Eventually, in FIG. 3, since the time from time t _{3 to} time t ₄ is shorter than the predetermined time T _c , the valve 13 cannot be opened and the angle error θ _err (= 10 °) is not corrected.

That is, in the hydraulic power steering apparatus according to the present invention, the angle error θ _err exceeding the threshold θ _THP is corrected when the reverse rotation is performed longer than the predetermined time T _c .
As is clear from steps S6 and S11 of FIGS. 4 and 2, the negative angle error θ _{err that} is lower than the threshold θ _THN is corrected when a forward rotation longer than the predetermined time T _c is performed.

When the steering direction is changed to reverse at time t ₇ in FIG. 3, satisfy the condition of step S9, the determination of the timer time is performed (step S13), and the start instruction is given to the timer 26 (step S14). Then, until the time _{t 8,} step S2~S15 is repeatedly executed.
Beyond time t _8, the timer time is determined to have exceeded the predetermined time T _c (step S15), and the valve control signal S _B to the effect that opening the valve from flowing means control unit 24 to the valve 13 is output (step S16). Then, steps S2 to S16 are repeatedly executed.

Valve control signal S _B is the delay time T _on is elapsed since the output (= Time t ₉₎ Then, actual valve 13 is opened, the handle 4 is idles. Then, no longer satisfy the condition in step S7 since the angle error theta _err Beyond time t ₁₀ below a threshold theta _THP, the valve control signal S _B to the effect that closing the valve 13 is output, the reset instruction to the timer 26 This is done (step S8).

Thereafter, when the delay time T _off elapses (= time t ₁₁ ), the opened valve 13 is closed. Steering wheel angle theta _W at time _{t 11} is approximately -3 °, does not satisfy the condition in step S6 and S7. That is, since the angle error θ _err is within the allowable range, thereafter, correction by the valve 13 is not performed, and steps S2 to S8 are repeatedly executed.

As described above, according to the hydraulic power steering apparatus of the present invention, the correction by the valve is performed only when the steering direction is not changed for a predetermined time, so the steering direction is changed at a relatively early cycle. In this case, it is possible to prevent the angle error θ _err from deteriorating. Further, according to the hydraulic power steering apparatus of the present invention, when the steering direction is changed at a relatively slow cycle, the conventional angle error θ _err can be corrected.

1 is a block diagram of a hydraulic power steering apparatus having a handle angle correction function according to the present invention. It is a flowchart which shows operation | movement of the hydraulic power steering apparatus provided with the handle | steering-wheel angle correction function based on this invention. It is a graph which shows an example of operation of a hydraulic power steering device provided with a steering wheel angle amendment function concerning the present invention. It is a graph which shows another example of operation | movement of the hydraulic power steering apparatus provided with the handle | steering-wheel angle correction function based on this invention. FIG. 1 is a cargo handling vehicle to which a hydraulic power steering device is applied, in which FIG. 1 (A) is an overall perspective view, and FIG. It is a schematic diagram which shows the relationship between the steering wheel angle of a cargo handling vehicle, and a steering wheel angle. It is a block diagram of the conventional hydraulic power steering device. It is a block diagram of the hydraulic power steering device provided with the conventional steering wheel angle correction function. It is a graph which shows an example of operation | movement of the hydraulic type power steering apparatus provided with the conventional steering wheel angle correction function, Comprising: (A) is a graph in case a steering direction is changed with a comparatively slow period, (B) is a steering direction. It is a graph when is changed with a relatively fast cycle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cargo vehicle 2 Driving wheel 3 Steering wheel 4 Handle 5 Knob 10 Oil supply unit 11 Hydraulic control unit 12 Cylinder 13 Valve (flow means)
14 steering wheel angle sensor 15 steering wheel angle sensor 16 hydraulic line 17 hydraulic line 20 steering wheel angle correction unit 21 target steering wheel angle calculation unit 22 storage unit 23 error calculation unit 24 flow means control unit 25 steering direction determination unit 26 timer θ _H handle Angle θ _W Steering wheel angle θ _T Target steering wheel angle

Claims (3)

A handle, a hydraulic control unit connected to the handle, a cylinder for controlling an angle θ _W of a steered wheel, and a set of hydraulic lines for connecting the hydraulic control unit and the cylinder, and an angle θ of the handle An amount of oil corresponding to _H is sent to the cylinder through one of the hydraulic lines, and sent back to the hydraulic control unit through the other hydraulic line, thereby transmitting the operation of the handle to the steered wheels. Hydraulic power steering
i) When a control signal is input, flow means for causing the oil in the one hydraulic line to flow to the other hydraulic line and returning the oil to be sent to the cylinder to the hydraulic control unit;
ii) a handle angle sensor for detecting an angle θ _H of the handle;
iii) a steering wheel angle sensor for detecting the angle θ _W of the steering wheel;
iv) based on the angle theta _H of the handle, and the target steering wheel angle calculating unit for obtaining the target steering wheel angle theta _T,
v) an error calculation unit for _{obtaining the} angle error θ _err by the equation “θ _T −θ _W ”;
vi) based on the angle theta _H of the handle, the steering direction determination unit steering direction of the steering wheel it is determined whether a reverse or a forward,
said angle error theta _err obtained in vii) the error calculator, wherein the determined by the steering direction determination unit is with reference to the steering direction, the angle error theta _err is large and the steering direction than the first threshold value If There the state is reversed or the angle error theta _err, is small and the steering direction than the second threshold condition is a normal rotation continues for a predetermined time, the flowing means outputs said control signal A flow control means for flowing oil;
With
The hydraulic power steering apparatus according to claim 1, wherein the predetermined time is set in advance in a range of 10 m to 500 msec, which is an assumed half direction of the steering direction change .   2. The hydraulic power steering apparatus according to claim 1, wherein the first threshold is 1 to 10 °, and the second threshold is −1 to −10 °.   A traveling vehicle comprising the hydraulic power steering device according to claim 1.

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