JP2010284050A - Traveling control device, and forklift with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a traveling control device capable of performing control to keep a traveling speed constant individually for every element which affects a traveling resistance, and a forklift with the control device. <P>SOLUTION: The traveling control device has a gear case which accommodates a gear for transmitting the rotation of a motor to a traveling wheel, a temperature sensor which detects the temperature of the inside or the external surface of the gear case and outputs a temperature signal according to the temperature, a correction unit for correcting a traveling resistance factor according to the temperature signal, and a torque command unit which shifts a maximum torque curve (C<SB>0</SB>) relating a vehicle speed with a torque command value based on the traveling resistance factor after the correction and the operated variable of a speed command means, obtains the torque command value (for example, T<SB>2L</SB>, T<SB>2H</SB>) corresponding to the vehicle speed (for example, V<SB>2</SB>) based on a torque curve (C<SB>L</SB>, C<SB>H</SB>) after the shift, and then outputs the torque command value to the motor. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a travel control device that causes a vehicle to travel at a speed corresponding to an operation amount of a speed command means, and a forklift equipped with the device.

  In general, in a vehicle in which driving wheels are driven by a motor, a torque command value is determined according to an operation amount of speed command means such as an accelerator pedal, and the motor operates according to the torque command value. Thus, the vehicle can travel at a speed corresponding to the operation amount of the speed command means.

  In the above vehicle, it is desirable that the vehicle always travels at a constant speed if the amount of operation of the accelerator pedal by the driver is constant. If the relationship between the operation amount and the traveling speed of the vehicle is not constant, the driver must finely adjust the operation amount of the accelerator pedal so that the target speed is always obtained while looking at the speedometer, which is a burden.

  However, actually, the traveling speed fluctuates when traveling on a slope. Specifically, when traveling uphill, the traveling speed is lower than the speed according to the amount of operation of the accelerator pedal. Conversely, when traveling downhill, the traveling speed increases. Even on a flat road surface, the vehicle speed may fluctuate due to the influence of the road surface condition (ease of slipping, unevenness, etc.) and the load caused by the load.

  As a travel control device for a vehicle that attempts to solve the above problem, for example, a device described in Patent Document 1 is known. In this travel control device, the travel resistance is obtained from the relationship between the actual output torque of the motor and the speed change of the vehicle. And the electric power for driving a motor is increased / decreased according to the amount of this running resistance, and, thereby, the vehicle can be accelerated at a constant speed.

JP-A-9-65512

  By the way, the running resistance of the vehicle changes under the influence of various factors such as the ambient temperature and the elapsed time (operation time) from the start of operation in addition to the above described road surface inclination, road surface condition, and load of the load. Is known empirically. However, in the above-described conventional travel control device, the travel resistance is obtained based on the actual speed change of the vehicle without distinguishing each of the above-described elements, so that flexible control corresponding to each element cannot be performed.

  Specifically, the load of the load is not controlled so as to keep the traveling speed constant, and the speed decreases as the load increases. It may be preferable also from a viewpoint. However, in the conventional travel control device, for example, it is possible to perform flexible control for each element, such as performing control so that the travel speed is constant with respect to changes in the ambient temperature and not controlling the load of the load. could not.

  Accordingly, it is an object of the present invention to provide a travel control device capable of performing control to keep the travel speed constant individually for each element that affects travel resistance, and a forklift equipped with the device. .

  In order to solve the above-described problem, the travel control device according to the first aspect of the present invention determines a torque command value for the motor that drives the traveling wheels according to the operation amount of the speed command means, and at a speed corresponding to the operation amount. A travel control device for a vehicle configured to travel, wherein a gear case containing a gear for transmitting rotation of the motor to the traveling wheel, and a temperature of an inner or outer surface of the gear case are detected, and the temperature is detected. A temperature sensor that outputs a temperature signal according to the temperature, a correction unit that corrects the running resistance coefficient according to the temperature signal, and at least the corrected running resistance coefficient and the operation amount of the speed command means, A maximum torque curve relating the vehicle speed and the torque command value is shifted, and a torque command value corresponding to the speed of the vehicle is obtained based on the torque curve after the shift. The click command value and a, the torque command unit for outputting to the motor.

  The travel control apparatus according to the first aspect of the present invention preferably further includes a storage unit storing a relationship between the temperature and the travel resistance coefficient, and the correction unit performs the correction based on the relationship.

  Further, the travel control device according to the second invention further includes a load sensor that detects a load and outputs a load signal corresponding to the load to the travel control device according to the first invention, The correction unit performs correction according to the temperature signal and correction according to the load signal.

  The storage unit of the travel control device according to the second invention further stores a relationship between the load and the travel resistance coefficient, and the correction unit preferably performs the correction based on the relationship. .

  In order to solve the above problems, a forklift according to the present invention includes the travel control device according to the first or second invention.

  ADVANTAGE OF THE INVENTION According to this invention, the forklift provided with the traveling control apparatus which can perform the control which maintains constant traveling speed separately for every element which influences traveling resistance, and this apparatus can be provided.

  More specifically, according to the travel control device of the first aspect of the invention, the speed variation caused by changes in the ambient air temperature and the operating time is obtained by correcting the travel resistance coefficient in accordance with the temperature of the inner or outer surface of the gear case. Can be suppressed. Further, according to the travel control device of the second invention, by correcting the travel resistance coefficient according to the load of the load, in addition to the ambient air temperature and the operation time, the speed fluctuation caused by the change of the load can be obtained. Can be suppressed.

It is a perspective view of a forklift. 1 is a block diagram of a travel control apparatus according to a first embodiment. It is an example of the correction map which shows the relationship between the gear case temperature and running resistance coefficient which are stored in the memory | storage part. It is a torque curve which relates a speed and a torque command value, (A) is a figure showing change of a torque curve by amendment, (B) and (C) are by operating an accelerator pedal of an amended torque curve It is a figure which shows a change. FIG. 6 is a block diagram of a travel control device according to a second embodiment. It is an example of the correction map which shows the relationship between the load and the change rate of a driving | running | working resistance coefficient stored in the memory | storage part.

  Hereinafter, with reference to the attached drawings, a preferred embodiment of a travel control means and a forklift according to the present invention will be described.

  The travel control apparatus according to the first embodiment is provided, for example, in a reach-type forklift 1 as shown in FIG. As shown in this figure, the forklift 1 has a mast 2 that slides back and forth, a lift cylinder 4 provided on the mast 2, and hydraulic oil flows between the lift cylinder 4 and an oil tank (not shown). Is provided with a fork 3 that moves up and down along the mast 2 and a traveling wheel 5 arranged at the rear of the vehicle body. The forklift 1 is provided with a travel control device 10a, and a driver's seat is provided with speed command means 6 (not shown). The speed command means 6 is, for example, an accelerator pedal. However, any speed command means 6 such as a pedal shape, a lever shape, and a grip shape can be applied to the present invention.

  FIG. 2 is a block diagram of the travel control device 10a and its peripheral members according to the present embodiment. As shown in this figure, the travel control device 10a includes a control unit 11a that determines a torque command value based on an operation amount of the speed command means 6, and a motor drive unit 16 that drives a motor 17 according to the torque command value. A gear case 18 connected between the motor 17 and the traveling wheel 5 is provided. A plurality of gears are accommodated in the gear case 18 so that the shaft rotation of the motor 17 is transmitted to the traveling wheels 5. The gear case 18 is filled with a lubricant such as grease for reducing gear wear.

  The traveling control device 10a further includes three sensors 21, 22, and 23. Among these, the temperature sensor 21 is provided in the vicinity of the gear case 18 and detects the temperature of the inside or the outer surface of the gear case 18. The speed sensor 22 is provided in the vicinity of the motor 17 and detects the number of rotations of the motor 17 by directly referring to changes in the current and magnetic field flowing through the motor 17 or the shaft rotation of the motor 17. Since the relationship between the rotational speed of the motor 17 and the rotational speed of the traveling wheel 5 is known, the rotational speed of the motor 17 is equivalent to the traveling speed of the forklift 1. The load sensor 23 is provided in the middle of the pipe connecting the lift cylinder 4 and the oil pump, and detects the load of the load loaded on the fork 3 based on the hydraulic pressure in the pipe.

  An appropriate electrical signal (= temperature signal) relating to the detected temperature is output from the temperature sensor 21. Similarly, a speed signal is output from the speed sensor 22, and a load signal is output from the load sensor 23. Each output signal is input to the control unit 11a.

As shown in FIG. 2, the control unit 11 a includes a torque command unit 15 and a first correction unit 13. Among them, the torque command unit 15, the running resistance coefficient of the forklift 1 mu, based on the vehicle weight W and the load W _B, the required torque T which are required to determine a torque command value calculated by the following equation.

Necessary shaft torque T = α × running resistance coefficient μ × (vehicle weight W + load W _B ) (1)

Here, the symbol α is an arbitrary constant including the gear ratio of the gear accommodated in the gear case 18, the gear efficiency, the diameter of the traveling wheel 5, and the like. The required shaft torque T is a torque that should be generated by the motor 17 when the operation amount of the speed command means 6 is the maximum and the traveling speed of the forklift 1 is the maximum (= V _MAX ).

As apparent from the above equation (1), the running resistance coefficient μ or the load W _B increases, required torque T increases. As a result, the motor 17 is controlled to generate a larger torque, and the traveling speed of the forklift 1 is increased. On the other hand, required torque T when the running resistance coefficient μ or the load W _B is reduced is reduced, the traveling speed of the forklift 1 are reduced.

  The first correction unit 13 of the control unit 11a corrects the running resistance coefficient μ used in the torque command unit 15 in advance based on the temperature signal output from the temperature sensor 21. Although correction can be performed by various methods, in this embodiment, correction is performed by referring to a correction map 19 (for example, FIG. 3) stored in the storage unit 12a.

  Here, the correction of the running resistance coefficient μ based on the temperature of the inside or the outer surface of the gear case 18 is based on the experiment conducted by the inventors of the present application, based on the viscosity of the grease filled in the gear case 18. This is because it has been found that the traveling speed of 1 fluctuates. In general, the viscosity of the grease decreases as the ambient temperature increases. Further, since the temperature of the gear case 18 increases as the operation time of the forklift 1 increases, the viscosity of the grease also decreases. Therefore, if the temperature of the gear case 18 is measured and a correction is made to increase or decrease the running resistance coefficient μ based on the temperature, the running caused by the ambient temperature or the operating time when the operation amount of the speed command means 6 is constant. Speed fluctuation can be canceled.

  As shown in FIG. 3, the correction map 19 shows the relationship between the temperature of the gear case 18 and the running resistance coefficient μ. As described above, the viscosity of the grease decreases as the temperature increases. Has come to decline. On the other hand, since the viscosity of the grease increases as the temperature decreases, the running resistance coefficient μ increases. In the example shown in FIG. 3, when the temperature increases from 20 ° C. to 35 ° C., the running resistance coefficient μ decreases from 0.0170 to 0.0125. Further, when the temperature decreases from 20 ° C. to 5 ° C., the running resistance coefficient μ increases from 0.0170 to 0.0215.

  The correction map 19 can also be an increase / decrease amount from the reference temperature. For example, when 20 ° C. is set as the reference temperature, data corresponding to 5 ° C. is 0.0045 (= 0.0215−0.0170), and data corresponding to 35 ° C. is −0.045 (= 0.0125− 0.0170).

  As a result, the travel resistance coefficient μ corresponding to the temperature (temperature signal) of the gear case 18 can be obtained by any of the correction maps 19. The correction map 19 is created in advance by measuring the running resistance coefficient μ for each temperature while actually running the forklift 1 or by predicting the running resistance coefficient μ for each temperature by computer simulation. Is.

  When the required shaft torque T is obtained by the above equation (1) using the corrected running resistance coefficient μ, the torque command unit 15 subsequently outputs a torque command to be output to the motor drive unit 16 by the method shown in FIG. Determine the value.

Specifically, assuming that the required shaft torque when correction is not performed (or when the temperature is the reference temperature) is T ₀ , the required shaft torque T at high temperature and low temperature is T _H and T _L , respectively. It becomes. If the torque curve when not corrected (hereinafter referred to as “maximum torque curve”) is C ₀ , the torque curves at high temperature and low temperature are C _H and C _L , respectively. As shown in FIG. 4A, the torque curve C _H has a shape as if the maximum torque curve C ₀ was shifted downward by an amount proportional to “T _H −T ₀ ”. Further, the torque curve C _L has a form in which the maximum torque curve C ₀ is shifted upward by an amount proportional to “T _L −T ₀ ”.

FIG. 4B shows a torque curve when correction at a low temperature is performed. As shown in this figure, when the operation amount of the speed command unit 6 changes between A ₀ to A ₆ (maximum), accordingly, the torque curve varies the torque curve C _L as the upper limit. The operation amount of the speed command means 6 in the case of A _2, the torque command value by using the torque curve C _2L are determined. For example, when the traveling speed of the forklift 1 is V _2, the torque command value becomes T _2L.

On the other hand, correction is performed at high temperatures (FIG. 4 (C)), and the operation amount of the speed command means 6 in the case of A _2, the torque command value by using the torque curve C _2H is determined. For example, when the traveling speed of the forklift 1 is V _2, the torque command value becomes T _2H.

As is clear from the comparison between FIGS. 4B and 4C, the torque command value T _2L is higher than the torque command value T _2H . That is, in the travel control device 10a according to the first embodiment, the torque command value is increased or decreased by correction based on the temperature of the gear case 18 even if the operation amount of the speed command means 6 is the same. Therefore, according to the traveling control apparatus 10a, the fluctuation | variation of the traveling speed resulting from ambient temperature or operation time can be canceled.

  Next, a travel control apparatus according to the second embodiment will be described. Similar to the first embodiment, the travel control apparatus according to the present embodiment is provided in a reach-type forklift 1 as shown in FIG.

In the running control apparatus in accordance with the present embodiment, in addition to the temperature, also perform further correction for load W _B of the load. Note that contains load W _B in the above equation (1). Therefore, since it is taken into account to some extent the load W _B of cargo even in the running control apparatus in accordance with the first embodiment, so that the load W _B is increased needs torque T with increasing generates a motor 17 Gayori large torque It has become. However, the present inventor has experimentally, the load W _B is also affect the running resistance coefficient mu, and the extent of its influence was found to vary with the type of forklift. Example 2 travel control device according to are those so as to cancel more accurately the variation of the running speed due to the load W _B based on the above findings.

FIG. 5 is a block diagram of the travel control device 10b and its peripheral members according to the second embodiment. As shown in this figure, the control unit 11b includes a torque command unit 15 and two correction units (a first correction unit 13 and a second correction unit 14). Among them, the torque command unit 15, in the same manner as in Example 1, the running resistance coefficient of the forklift 1 mu, based on the vehicle weight W and the load W _B, the required torque T which are required to determine a torque command value Ask.

  The first correction unit 13 corrects the running resistance coefficient μ based on the temperature signal output from the temperature sensor 21. At this time, the first correction unit 13 refers to the correction map 19 stored in the storage unit 12b.

In addition, the second correction unit 14 further corrects the running resistance coefficient μ corrected by the first correction unit 13 based on the load signal output from the load sensor 23. That is, the torque command unit 15, necessary torque T using the running resistance coefficient μ after the correction for the load W _B by the correction and a second correction unit 14 regarding the temperature of the first correction portion 13 has been performed is determined. Although the correction can be performed by various methods, in this embodiment, the correction is performed by referring to the correction map 20 stored in the storage unit 12b.

As shown in FIG. 6, the correction map 20 shows the relationship between load W _B and the running resistance coefficient μ of the rate of change of load. Specifically, since the travel control device 10b according to the present embodiment is provided in the reach-type forklift 1, the relationship of the graph 20a is stored in the correction map 20. On the other hand, when the counter balance type forklift is provided, the correction map 20 stores the relationship of the graph 20b. That is, the correction map 20 stores a relationship corresponding to the type of forklift. Each relationship is obtained in advance by experiments.

Here, the relationship between the load W _B and the running resistance coefficient μ of the rate of change I'm kind of forklift difference is due to the following reasons. That is, in the reach-type forklift, when the load W _B of the load is increased, the vehicle center of gravity is moved from the front vehicle body, the friction between the running wheel 5 and the road surface that is attached to the rear of the vehicle body is reduced. In contrast, in counterbalance type forklift, so is provided with a running wheel in front of the vehicle body, the friction between the running wheel and the road surface load W _B is increased to increase. In other words, different masts 2 depending on the type of forklift and (fork 3) to the geometrical positional relation between the running wheels 5 are different, depending the kinds of forklifts relationship between load W _B and the running resistance coefficient μ of the rate of change.

As shown in the graph 20a in FIG. 6, the forklift 1 of the reach type, rate of change of the running resistance coefficient μ decreases as the load W _B increases. That is, the running resistance coefficient μ decreases as the load W _B is increased, resulting in any traveling speed of the forklift 1 to be carried out correction is increasing.

Therefore, the second correction unit 14 further corrects the running resistance coefficient μ corrected by the first correction unit 13. In the example shown in FIG. 6, the rate of change in case load W _B is W ₁ is so -10%, the second correcting unit 14, the running resistance coefficient μ after being corrected by the first correcting unit 13 decreased by 10% Let As a result, the required shaft torque T obtained by the above equation (1) is reduced by 10%, and the motor 17 is controlled to generate a smaller torque than when the correction is not performed.

After all, according to the travel control device 10b according to the second embodiment performs a correction for the ambient temperature and the operating time, the two correction and correction for the load W _B cargo continuously variation of the running speed due to these Can be canceled.

  The preferred embodiments of the travel control device and the forklift according to the present invention have been described above, but the present invention is not limited to these configurations.

  For example, only correction related to temperature is performed in the first embodiment, and correction related to temperature and load is performed in the second embodiment. However, only correction of load may be performed, and another correction may be additionally performed. It can also be done. In other words, in the travel control device according to the present invention, since it is possible to perform control for keeping the travel speed constant for each element that affects travel resistance, control for keeping the travel speed constant only for certain elements is performed. Or exclude certain elements.

  In each embodiment, the running resistance coefficient used for calculation in the torque command unit is corrected. Alternatively, the torque command value output from the torque command unit may be corrected instead. The effect of can be obtained.

  Moreover, the gear case of FIG. 2 and FIG. 5 is an example, and there are no particular limitations on the number, type, meshing mode, and the like of the gears accommodated.

1 Forklift 2 Mast 3 Fork 4 Lift cylinder 5 Traveling wheel 6 Speed command means (accelerator pedal)
10a, b Travel control device 11a, b Control unit 12a, b Storage unit 13 First correction unit (temperature)
14 Second corrector (load)
15 Torque command section 16 Motor drive section 17 Motor 18 Gear case 19 Correction map (temperature)
20 Correction map (load)
21 Temperature sensor 22 Speed sensor 23 Load sensor

Claims (5)

A travel control device for a vehicle configured to determine a torque command value for a motor that drives a traveling wheel according to an operation amount of a speed command means, and to travel at a speed according to the operation amount,
A gear case containing a gear for transmitting the rotation of the motor to the traveling wheel;
A temperature sensor that detects the temperature of the inner or outer surface of the gear case and outputs a temperature signal corresponding to the temperature; and
A correction unit that corrects the running resistance coefficient in accordance with the temperature signal;
Based on at least the corrected running resistance coefficient and the operation amount of the speed command means, a maximum torque curve relating the speed of the vehicle and the torque command value is shifted, and based on the torque curve after the shift, Obtaining a torque command value corresponding to the speed of the vehicle, and outputting the torque command value to the motor;
A travel control device comprising: A storage unit storing a relationship between the temperature and the running resistance coefficient;
The travel control apparatus according to claim 1, wherein the correction unit performs the correction based on the relationship. A load sensor that detects a load and outputs a load signal corresponding to the load;
The travel control apparatus according to claim 1, wherein the correction unit performs correction according to the temperature signal and correction according to the load signal. The storage unit further stores a relationship between the load and the running resistance coefficient,
The travel control apparatus according to claim 3, wherein the correction unit performs the correction based on the relationship.   A forklift comprising the travel control device according to claim 1.

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