JP2003267697A - Battery type forklift truck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery type forklift truck that can continuously smoothly travel by ensuring a given maximum speed from just after a start of operation irrespective of a warm-up condition. <P>SOLUTION: The battery type forklift truck comprises a speed detecting means 4 for detecting the rotating speed of a traveling motor 2, a temperature sensor 5 for detecting a current warm-up temperature tx of a vehicle body, a reference torque setting means 21 for setting a driving torque Tw corresponding to a rotating speed V of the traveling motor 2 at a given reference temperature tw, and a motor controlling means 22 for correcting the driving torque Tw according to a difference between the warm-up temperature tx detected by the temperature sensor 5 and the reference temperature tw, and controlling the drive of the traveling motor 2 with the corrected torque Tx. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery-powered forklift truck, and more particularly to a technique for achieving a predetermined running performance without being affected by a warm-up state.

[0002]

2. Description of the Related Art Conventionally, among forklifts, there is a battery-type forklift that supplies electric power from a battery mounted on a vehicle body to various motors to carry out traveling and cargo handling work. Compared to other things, it is quieter and does not emit exhaust gas, so it has the advantage of being environmentally friendly.

When a battery-powered forklift is to be traveled, for example, a driver operates an accelerator lever or an accelerator pedal provided on a vehicle body to drive the travel motor with an output torque according to the operation amount, and the travel motor. Drive wheels, which are connected to each other via a driving force transmission mechanism such as a gear box, are rotated to travel. Then, the more the operation amount of the accelerator lever or the accelerator pedal is, the faster the traveling motor is rotated, so that the traveling speed of the battery-powered forklift truck is increased, and the traveling motor is rotated when the accelerator lever or the accelerator pedal is not operated. The battery-powered forklift also stops. The drive control of the traveling motor according to the operation amount of the accelerator lever or the accelerator pedal is performed by the control device provided in the vehicle body.

The relationship between the operation amount of the accelerator lever or the accelerator pedal and the rotation speed of the traveling motor is uniquely set in the controller, and the controller determines the rotation speed of the traveling motor based on this relationship. decide. Further, as shown in FIG. 4, a relationship (hereinafter also referred to as a torque curve) between the rotation speed of the traveling motor and the output torque is uniquely set in the control device. The drive motor is driven and controlled by the output torque determined based on the above.
That is, in order to prevent the output torque to the running motor from becoming excessive, the maximum torque determined by the maximum permissible current of the running motor is output in the low speed region of the motor rotation speed, and the rotation speed of the running motor in the middle and high speed regions. The output torque is set to gradually decrease with increasing speed. At this time, the torque curve is set with reference to the state where the vehicle is sufficiently warmed up.

[0005]

By the way, when the vehicle is not sufficiently warmed up, for example, the viscous resistance of the gear oil in the gear box of the driving force transmission mechanism is large, and these become the running resistance inside the vehicle. The load torque increases. As described above, conventionally, the torque curve is uniquely determined irrespective of the warm-up state. Therefore, unless the warm-up operation is performed sufficiently, the load torque is large and the maximum speed cannot be obtained. In particular, when the outside air temperature is low in winter or cold regions, the load torque becomes large and it takes time to reach the maximum speed.

For example, in the torque curve of FIG. 4, when it is assumed that the maximum speed is obtained at the rotation speed Va of the traveling motor corresponding to the load torque Ta after the warm-up operation is sufficiently performed, the outside air temperature is low. When the load torque is as large as Tb, the rotation speed of the traveling motor becomes Vb, and at this time, it does not reach the maximum speed Va in the warm-up state. If the warm-up operation is sufficiently performed, the maximum speed gradually changes from Vb to Va, but it takes extra time until that time.

As described above, conventionally, when the outside air temperature is low, such as in cold regions or winter, the desired maximum speed cannot be obtained immediately after the start of operation, and it takes time until the desired maximum speed is obtained. Requires. In addition, the driving feeling greatly changes immediately after the start of operation due to seasonal changes such as summer and winter, which makes driving difficult and impairs the smoothness of cargo handling work.

The present invention has been made in order to solve the above-mentioned problems, and a predetermined maximum speed can be obtained immediately after the start of operation without being affected by the warm-up state, so that the vehicle always runs smoothly. It is an object of the present invention to provide a battery-powered forklift truck that is made possible.

[0009]

The present invention has the following features to attain the object mentioned above. That is, the battery-type forklift according to the invention of claim 1 is a battery-type forklift that travels by rotating the drive wheels by a traveling motor, the speed detecting means for detecting a rotation speed of the traveling motor, and a vehicle body. Temperature detecting means for detecting the current warm-up temperature of the vehicle, reference torque setting means for setting a driving torque according to the rotation speed of the traveling motor at a predetermined reference temperature, and the warming temperature detected by the temperature detecting means. Motor control means for correcting the drive torque based on the difference between the machine temperature and the reference temperature, and controlling the drive of the traveling motor with the corrected torque.

According to this structure, the reference torque setting means sets the drive torque according to the rotation speed of the traveling motor, and the drive torque is set by the motor control means based on the difference between the warm-up temperature and the reference temperature. The driving motor is drive-controlled with the corrected torque. Therefore, it is possible to drive the traveling motor with an appropriate torque according to the warm-up temperature, and as a result, there is no fear that the necessary traveling speed cannot be obtained because the vehicle is not sufficiently warmed up. Therefore, workability can be improved.

According to a second aspect of the present invention, in the battery type forklift truck according to the first aspect of the invention, the temperature detecting means is a gear oil in a gear box for transmitting the rotation of the traveling motor to the drive wheels. Or the temperature of an electric device related to the rotation of the traveling motor is detected as the warm-up temperature.

According to this structure, since the temperature of the gear oil and the temperature of the electric equipment related to the rotation of the traveling motor directly represent the warming-up state of the vehicle body, the temperature of the gear oil, Alternatively, an accurate warm-up state of the vehicle body can be reflected in the correction of the drive torque by detecting the temperature of the electric device related to the rotation of the traveling motor as the warm-up temperature.

According to a third aspect of the present invention, in the configuration of the first or second aspect of the invention, the reference torque setting means includes the drive torque at the first reference temperature indicating a warm-up completion state and the first torque. The drive torque at a second reference temperature lower than the reference temperature of, and the motor control means sets the drive torque at the first reference temperature and the drive torque at the second reference temperature. The difference is proportionally distributed based on the difference between the warm-up temperature and the first reference temperature and added to the drive torque at the first reference temperature for correction.

According to this structure, the reference torque setting means makes the driving torques different between the first reference temperature indicating the warm-up completion state and the second reference temperature lower than the first reference temperature. Is set, by the motor control means,
The difference in these drive torques is proportionally distributed based on the difference between the warm-up temperature and the first reference temperature, and the proportionally distributed portion is the first
The correction is performed by adding to the drive torque at the reference temperature of. Therefore, the drive torque at the first reference temperature can be corrected to an appropriate torque according to the current warm-up temperature.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a travel control system of a battery-powered forklift according to an embodiment of the present invention. The battery-powered forklift according to the present embodiment is not particularly limited to a counterbalanced or reach-type forklift as long as it uses a battery as a driving power source.

In FIG. 1, 1 is an accelerator lever for speed adjustment, 2 is a traveling motor for driving drive wheels, 3 is a traveling motor drive unit for driving a traveling motor 2, and
Reference numeral 4 is a speed detecting means for detecting the rotation speed of the traveling motor 2, 5 is a temperature sensor as a temperature detecting means for detecting the current warm-up temperature, and 6 is a controller including a microcomputer or the like.

The accelerator lever 1 has a built-in potentiometer for detecting its operation amount θ, and the speed detecting means 4 is composed of, for example, a rotary encoder attached to the drive shaft of the traveling motor 2. Further, the temperature sensor 5 is attached to the gear box in the present embodiment and detects the temperature of the internal gear oil as the current warm-up temperature. The temperature sensor 5 may be attached to the gearbox, and may be configured to detect the temperature of a board or an element forming the traveling motor drive unit 3 or the controller 6 as a warm-up temperature.

As shown in FIG. 1, the operation amount θ of the accelerator lever 1 is input to the controller 6, the current warm-up temperature tx is input from the temperature sensor 5, and the traveling motor 2 is input from the speed detecting means 4. The rotation speed V of is input.
Then, based on these inputs, the controller 6 executes the control described in detail below.

The controller 6 has a built-in memory, such as a ROM, in which relational data between the operation amount θ of the accelerator lever 1 and the target rotation speed Vo of the traveling motor 2 is stored in advance. When the operation amount θ of the accelerator lever 1 is input to the controller 6, the controller 6 reads the target rotation speed Vo corresponding to the operation amount θ of the accelerator lever 1 from this memory to determine the target rotation speed Vo. Execute the process. And
The output torque of the traveling motor 2 is determined so that the rotation speed V detected by the speed detection means 4 and the target rotation speed Vo match.

Further, the above memory is optimally set (for example, the most efficient from the viewpoint of power consumption) at the warm-up temperature tw (for example, 40 ° C.) as shown by the broken line in FIG. The relational data between the rotational speed V and the output torque Tw is stored in advance, and the controller 6 reads out the relational data from the memory, and the relational data and the current warm-up temperature tx detected by the temperature sensor 5.
And the rotational speed V are used to perform calculation, and the output torque Tx determination process is executed. The warm-up temperature tw (for example, 40
Is the first reference temperature in the present invention, and the process by which the controller 6 reads the relational data of the rotation speed V and the output torque Tw from the memory is the reference torque setting means in the present invention.

(A) When the low speed region controller 6 determines that the rotation speed V is in the range of 0 <V≤V1, the output torque Tx corresponding to the current warm-up temperature tx is always a constant value Tmax. To decide.
That is, Tx = Tmax (1) Here, V1 is preset as the rotation speed of the traveling motor 2 when the traveling speed of the forklift is 3 km / h, for example, and Tmax is 3 k / h.
The torque is such that a predetermined climbing ability can be realized when traveling at a low speed of m or less, and the current flowing through the traveling motor 2 and the electric components for driving the traveling motor 2 is preset so as not to exceed an allowable value. It is torque.

(B) When the high speed region controller 6 determines that the rotation speed V is within the range of V2 <V≤Vmax, the output torque Tx corresponding to the current warm-up temperature tx is calculated by the following calculation. decide. That is, Tx = Tw + ΔTm · (tw-tx) / (tw-tc) (2) where ΔTm = Tcm-Twm, where V2 is, for example, the traveling motor 2 when the traveling speed of the forklift is 9 km / h. Rotation speed of Vm
The ax is preset as the rotational speed of the traveling motor 2 when the traveling speed of the forklift reaches the maximum hourly speed (for example, 12 km / h). Also, Tcm
Is the temperature tc in the unwarmed state (eg 0 ° C)
Is the torque required to make the traveling speed of the forklift at the maximum speed, and t
The data of c and Tcm are stored in the memory of the controller 6. Note that Twm is the rotational speed V and the output torque T
It is the value of the output torque Tw when V = Vmax in the relational data with w. The warm-up temperature tc (for example, 0 ° C.) is the second reference temperature in the present invention, and the process of the controller 6 reading the data of the output torque Tcm from the memory is also the reference torque setting means in the present invention.

As described above, since the load torque is large in the non-warmed-up state, the output torque Tcm corresponding to the rotation speed Vmax at the warmed-up temperature tc (eg 0 ° C.).
Is the rotation speed V at the warm-up temperature tw (for example, 40 ° C.).
The output torque Twm corresponding to max is increased by ΔTm. In the present embodiment, tx =
As is apparent by substituting tc, a certain rotation speed Va
The output torque Ta at the warm-up temperature tc (for example, 0 ° C.) corresponding to (V2 <Va ≦ Vmax) is Ta = Tw + Δ.
It is determined as Tm, and the relationship between the rotation speed V and the output torque Tc at the warm-up temperature tc is a torque curve shown by the one-dot chain line in FIG. Further, at some warm-up temperature tx (tc <tx <tw), the torque increment ΔTm is proportionally distributed according to the warm-up temperature tx and added to the output torque Tw to obtain the output torque Tx. I ask for it. Therefore, the relationship between the rotation speed V and the output torque Tx at the warm-up temperature tx is the torque curve shown by the solid line in FIG. Then, when the warm-up operation is sufficiently performed and the warm air temperature tx becomes high and tx = tw, Tx = Tw from the equation (2).
Becomes

(C) When the medium speed range controller 6 determines that the rotation speed V is in the range of V1 <V≤V2, the output torque Tx corresponding to the current warm-up temperature tx is calculated as follows. Determined by. That is, Tx = Tw + ΔTm · (tw-tx) / (tw-tc) · (V−V1) / (V2-V1) (3) That is, the torque increment ΔTm is warmed up in the high speed region (V2 <V ≦ Vmax). What is proportionally distributed according to the machine temperature tx is added to the output torque Tw, but in the medium speed range (V1 <V ≦ V
In 2), the torque increment ΔTm is set to the warm-up temperature tx and the rotation speed V.
The output torque Tx is determined by adding a proportional distribution according to the above to the output torque Tw.

The output torque Tw at the warm-up temperature tw (for example, 40 ° C.) corresponding to the rotation speed V = V1 is
Tw = Tmax.

Therefore, in the range of 0 <V ≦ Vmax,
The output torque Tx at the warm-up temperature tx becomes one torque curve shown by the solid line in FIG. 2, and the drive motor 2 is drive-controlled by the output torque Tx thus determined by the controller 6. The process of correcting the output torque Tw by the controller 6 to determine the output torque Tx and the process of drivingly controlling the traveling motor 2 with the output torque Tx are the motor control means in the present invention.

For example, when the accelerator lever 1 is operated so that the traveling speed is the maximum speed while the forklift is stopped, the target rotation speed Vo = Vmax, and the rotation speed V coincides with this target rotation speed Vo. The traveling motor 2 is controlled so as to do so. Rotation speed V is 0 ≦ V ≦ V1
In the range, the traveling motor 2 is driven with the output torque Tx (= Tmax) determined by the calculation of the equation (1), and the traveling speed of the forklift gradually increases as the rotation speed V increases. When the rotation speed V is in the range of V1 <V ≦ V2, the traveling motor 2 is driven by the output torque Tx determined by the calculation of the equation (3), and the rotation speed V is further increased so that the rotation speed V is V2 <V ≦. In the range of Vmax,
The traveling motor 2 is driven with the output torque Tx determined by the calculation of the equation (2). When the rotation speed V eventually matches the target rotation speed Vo (= Vmax), the output torque Tx
Becomes Tx = Twm + ΔTm · (tw-tx) / (tw-tc) (4), the drive of the traveling motor 6 at this output torque Tx is maintained, and the forklift continues traveling at the maximum speed. The formula (4) is obtained by using the formula (2) as the rotation speed V = Vmax.
It is limited to. When the warm-up temperature tx rises as the vehicle continues running and tx = tw, the output torque Tx becomes Tx = Twm. In the present embodiment, the warm-up temperature tx detected by the temperature sensor 5 is limited to the range of tc ≦ tx ≦ tw. If tx> tw, it is considered that tx = tw, and tx <tc. Sometimes, the output torque Tx is determined by regarding tx = tc.

Next, the traveling control operation by the controller 6 in the battery type forklift having the above-mentioned structure will be described with reference to the torque curve shown in FIG. 2 and the flowchart shown in FIG. The symbol S means each step.

First, the controller 6 includes the speed detecting means 4
The rotation speed V of the traveling motor 2 detected by is acquired (S1). Subsequently, it is determined whether the rotation speed V is equal to or lower than a predetermined value V1 (S2), and if the result is Yes, (1)
The output torque Tx is determined to be Tmax by the calculation of the formula (S
3), the traveling motor 2 is driven with this output torque Tmax (S4).

If the determination result in step S2 is No, the warm-up temperature tx detected by the temperature sensor 5 is taken in (S5), and it is determined whether the rotation speed V is equal to or lower than a predetermined value V2 (S6). If this determination result is Yes, the output torque Tx is determined by the calculation of the equation (3) (S
7) Then, the traveling motor 2 is driven with this output torque Tx (S4).

On the other hand, in step S6, the judgment result is N.
When it becomes o, the output torque Tx is determined by the calculation of the equation (2) (S8), and the traveling motor 2 is driven by this output torque Tx (S4).

Therefore, the state of not warming up (tx
= Tc), the load torque is large. Therefore, for example, in order to drive the forklift at the maximum speed, the output torque Tcm is necessary to set the rotation speed of the traveling motor 6 to Vmax. Since the output torque was set only based on the torque curve of, the rotation speed is Vc (<Vma at the output torque Tcm.
x), and it was not possible to travel at the maximum speed, while in this embodiment, as shown in equation (4),
Since the output torque Tx for traveling at maximum speed is determined according to the warm-up temperature tx, it is possible to travel at maximum speed immediately after the start of operation.

Further, in this embodiment, the traveling motor 2 is rotating at the rotation speed V in the range of V1 <V≤Vmax, and the current warm-up temperature tx detected by the temperature sensor 5 is tw. Output torque Tx only when
However, since the torque increment ΔTm is proportionally distributed according to the warm-up temperature tx, the torque increment ΔTm is increased more than the output torque Tw when the warm-up operation is sufficiently performed (tx = tw).
There is no fear that an overcurrent will flow to the traveling motor 2 or equipment such as the controller 6 or the traveling motor drive unit 3 will be overheated, resulting in a failure.

Further, in this embodiment, from the viewpoint of power consumption, the efficiency deteriorates until the warm-up operation is sufficiently performed, but after the warm-up operation is sufficiently performed, the rotation speed is reduced. Since the traveling motor 2 is driven with the output torque Tw set so as to be most efficient with respect to the speed V, there is no possibility that the efficiency will deteriorate over a long period of time. Note that, in the past, it was not possible to drive the vehicle at the maximum speed until the warm-up operation was sufficiently performed, but in this embodiment, it is possible to perform the work by running the vehicle at the maximum speed immediately after the start of the operation. Even if the efficiency deteriorates from the viewpoint of consumption, the work efficiency will be greatly improved.

The arithmetic expression for determining the output torque explained in the above embodiment is not limited to the expressions shown in the equations (1) to (3), and deviates from the spirit of the present invention. It is possible to change appropriately within the range not to do. For example, in the equation (2), the torque increment ΔTm (= Tcm−Tw
m) is proportionally distributed according to the warm-up temperature tx and is added to the reference output torque Tw.
It is also possible that v = f (V), that is, the torque increment ΔTv represented by a function for the rotation speed V is proportionally distributed according to the warm-up temperature tx and added to the output torque Tw. Further, the relationship data between the optimally set rotation speed V and the output torque Tw at the warm-up temperature tw and the relationship data between the optimally set rotation speed V and the output torque Tw at the warm-up temperature tc are displayed. Store it in memory,
The torque increment ΔT may be obtained as ΔT = Tc−Tw, and the torque increment ΔT may be proportionally distributed according to the warm-up temperature tx and added to the output torque Tw.

[0036]

According to the first aspect of the present invention, since the drive motor is drive-controlled with an appropriate torque according to the warm-up temperature, it is not possible to drive at maximum speed immediately after the start of operation. It is possible to improve the workability because there is no possibility that the trouble that the required traveling speed cannot be obtained because the vehicle is not warmed up is generated.

According to the second aspect of the present invention, the accurate warm-up state of the vehicle body can be reflected in the correction of the drive torque, and as a result, the traveling motor can be driven with an appropriate torque.

According to the invention of claim 3, therefore,
The drive torque at the first reference temperature can be corrected to an appropriate torque according to the current warm-up temperature, and when necessary, the torque can be corrected according to the difference between the current warm-up temperature and the first reference temperature. Is increased (power consumption increases),
It does not cause a significant reduction in efficiency.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a travel control system of a battery-powered forklift according to an embodiment of the present invention.

2 is a schematic diagram of the battery-powered forklift of FIG.
It is a characteristic view which shows a torque curve.

FIG. 3 is a flowchart for explaining a traveling control operation of the controller in the battery-powered forklift according to the present invention.

FIG. 4 is a characteristic diagram showing a torque curve set in a conventional battery-powered forklift.

[Explanation of symbols]

2 Running motor 4 Speed detection means 5 Temperature sensor (temperature detection means) 6 controller 21 Reference torque setting means 22 Motor control means

Claims (3)

[Claims] 1. A battery-type forklift that travels while driving wheels are rotated by a traveling motor, the speed detecting means detecting a rotation speed of the traveling motor, and a temperature detecting a current warm-up temperature of a vehicle body. Detecting means, reference torque setting means for setting a drive torque according to the rotation speed of the traveling motor at a predetermined reference temperature, and a difference between the warm-up temperature and the reference temperature detected by the temperature detecting means. A battery-type forklift, comprising: a motor control unit that corrects the drive torque based on the drive torque, and controls the drive of the traveling motor with the corrected torque. 2. The temperature detecting means warms up the temperature of gear oil in a gear box for transmitting the rotation of the traveling motor to the drive wheels, or the temperature of an electric device related to the rotation of the traveling motor, to the warm-up. The battery-powered forklift according to claim 1, wherein the temperature is detected as a temperature. 3. The reference torque setting means sets the drive torque at a first reference temperature indicating a warm-up completion state and the drive torque at a second reference temperature lower than the first reference temperature. And setting the difference between the drive torque at the first reference temperature and the drive torque at the second reference temperature to the difference between the warm-up temperature and the first reference temperature. The battery-powered forklift according to claim 1 or 2, wherein the battery-based forklift is proportionally distributed based on the above-mentioned value and is added to the drive torque at the first reference temperature for correction.