JP2003235114A - Electric car controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric car controller that can reduce the speed or brake in accordance with the acceleration control by controlling the regenerative braking. <P>SOLUTION: A CPU computes an instructed torque of a traveling motor in such a way that actual traveling speed corresponds to a target speed (S4 to S6). When the computed an instructed torque represents regeneration (YES at S7), the instructed torque is limited so that a permissible torque is computed based on limited amount computed from the stepped down level of a limiting pedal (S8). Of the instructed torque and permissible torque, the torque of a smaller absolute value is adopted as the instructed torque (S9); and a regenerative torque required for down-slope regeneration, neutral regeneration, plugging regeneration, and maximum speed regeneration is each computed (S10). Of the computed regenerative torque and the instructed torque adopted as Step 9, the torque of the largest absolute value is used as a torque command value to control the output of the traveling motor (S11, S13). <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 forklift, an electric vehicle, or the like, which is driven by a traveling motor that uses a battery as a driving source to generate an output torque according to an operation amount of an accelerator and performs braking by regenerative braking of the traveling motor. The present invention relates to a control device for an electric vehicle.

[0002]

2. Description of the Related Art Generally, a battery forklift, which is an electric vehicle, is provided with a traveling motor that uses a battery as a drive source and is composed of, for example, an induction motor, and the control device controls the output of the traveling motor during power running to perform normal traveling. Done. On the other hand, during braking, in addition to braking by the brake, regenerative braking is performed in which the field current is controlled to use the traveling motor as a generator and the energy generated at that time is regenerated to the battery side for braking. Has become.

The braking of the battery forklift will be specifically described. There are two types of braking: mechanical braking and regenerative braking controlled by a control device. The former mechanical braking is used to operate a foot brake. There is braking, which activates the side brakes. In addition, as the regenerative braking controlled by the latter control device, downhill regenerative braking that regenerates so as not to accelerate when descending, neutral regenerative braking that regenerates to coast when there is no accelerator operation, and directional lever operation There is plugging regenerative braking when the traveling direction of is switched to the opposite direction.

At the time of braking, these braking functions are fully utilized to perform optimum braking suitable for the situation.

[0005]

However, in the case of the conventional braking control, for example, when going down a slope, the foot brake pedal is fully depressed, but when the load of the loaded load changes, the foot brake is changed. The braking characteristics of the vehicle will change, that is, the vehicle body is easily braked by the foot brake if there is no vehicle loaded, but even if the foot brake pedal is fully depressed if the loaded load is large. The vehicle body is less likely to be braked. Therefore, there is a problem that the driver cannot easily control the speed.

Also, when climbing a slope, the vehicle body slides down the slope before the accelerator is operated due to the load,
While so-called side alignment is required to match the timing of the side brake and the accelerator when starting on a slope, if the accelerator operation is stopped in the middle of the slope, there is the inconvenience of slipping down the slope.

Further, when the vehicle is stopped on a slope, it is always necessary to operate the side brake or the foot brake, and in particular, if the operator forgets to operate the side brake, the vehicle body will slip off.

[0008] Therefore, an object of the present invention is to provide an electric vehicle capable of decelerating or braking according to an accelerator operation amount by controlling regenerative braking.

[0009]

In order to achieve the above-mentioned object, the present invention provides a battery mounted on a vehicle body, and a traveling motor which uses this battery as a drive source to generate an output torque according to an operation amount of an accelerator. In a control device for an electric vehicle that performs braking by regenerative braking of the travel motor, a target speed derivation unit that derives a target speed according to an operation amount of the accelerator, and a rotation that detects a rotation speed of the travel motor. A detection unit, a torque derivation unit that derives an instruction torque such that the speed detected by the rotation detection unit becomes the target speed, an operation unit that applies a desired limit to the instruction torque, and the torque derivation unit And a control unit for controlling the output of the traveling motor by adding a limit according to the operation of the operation unit to the instruction torque when the instruction torque indicates regeneration. It is characterized in (Claim 1).

According to this structure, the control section
When it is determined that the torque commanded by the torque derivation unit represents regeneration, the command torque is limited according to the operation of the operation unit, and the output of the traveling motor is controlled. for that reason,
For example, even when the accelerator operation is stopped in the middle of a slope, by limiting the instruction torque for regeneration by operating the operation unit, the accelerator is not operated, that is, the speed becomes zero. It is possible to prevent the vehicle body from slipping down by holding the vehicle in a stopped state, and therefore it is possible to perform deceleration or braking according to the accelerator operation amount.

Further, the present invention is characterized in that the control section judges whether or not the instructed torque represents regeneration based on a traveling direction of the vehicle body and a polarity of the instructed torque (claim 2). With such a configuration, it is possible to accurately determine whether or not the instructed torque represents regeneration.

Further, according to the present invention, the control unit includes at least a downhill regeneration function for regenerating so as not to accelerate when descending, a neutral regeneration function for regenerating so as to coast when there is no accelerator operation, and the vehicle body. Is equipped with a plugging regenerative function when the traveling direction is switched to the opposite direction, derives the regenerative torque required for each of these regenerative functions, and adopts the largest absolute value of the instructed torque and the regenerative torque after limitation. Then, the output of the traveling motor is controlled (claim 3).

According to such a configuration, the descending slope regeneration function,
The regenerative torque required for each of the neutral regenerative function and plugging regenerative function, and the one with the largest absolute value among the limited command torques is used to control the output of the travel motor. Is zero, that is, regenerative braking when the instruction torque is not limited and regenerative braking when the instruction torque is limited can be selected according to the driver's preference, and the driver does not feel uncomfortable. Driving can be realized.

Further, the present invention is characterized in that the operation portion is provided with a pedal operable by a foot (claim 4). According to such a configuration, it is possible to control the limit amount of the instructed torque by operating the pedal with the foot, and therefore, it is suitable for the vehicle in which the driver sits on the seat and drives.

Further, the present invention is characterized in that the operation section includes an operation device which can be operated by hand (claim 5). According to such a configuration, it is possible to control the limit amount of the instruction torque by manually operating the operating device, which is suitable for a vehicle in which the driver stands up and drives.
At this time, as the operation device, for example, a lever that can change the tilt amount, a knob that can change the rotation amount, or the like is preferable.

Further, the present invention is characterized in that the operation section includes a detector for detecting an operation amount thereof (claim 6). With such a configuration, the operation amount of the pedal or the operation device can be reliably detected by the detector, and deceleration or braking can be realized according to the accelerator operation amount.

Further, according to the present invention, the control unit has a smaller operation amount of the operation unit detected by the detector,
It is characterized in that the degree of restriction applied to the instruction torque is increased (claim 7).

With such a configuration, the smaller the amount of operation of the operating portion, the greater the degree of restriction applied to the instruction torque, so the allowable value of the instruction torque for regenerating the traveling motor becomes smaller, and the regeneration is reduced. Braking is weakened. On the contrary, when the operation amount of the operation unit is large, the regenerative braking is strengthened. Therefore, the driver can operate the operation unit with the same feeling as a general mechanical brake.

Further, the present invention is characterized in that the control unit increases the degree of restriction applied to the instruction torque as the operation amount of the operation unit detected by the detector increases. 8).

With such a configuration, the greater the amount of operation of the operating portion, the greater the degree of restriction applied to the instruction torque, and therefore the allowable value of the instruction torque for regenerating the traveling motor becomes smaller, and the regeneration is reduced. Braking is weakened. For example, when the accelerator operation is stopped in the middle of a slope, if there is a time lag before the regenerative braking is applied with the maximum instruction torque, the vehicle will slide down. Therefore, for example, if the limit applied to the instruction torque is maximum when the operation amount is maximum and the limit applied to the instruction torque is zero when the operation amount is zero,
Immediately after stopping the accelerator operation, the limit applied to the instruction torque is zero, that is, regenerative braking is applied with the maximum instruction torque,
The car body does not slide down.

Further, the present invention is characterized in that the electric vehicle is a battery forklift (Claim 9). According to such a configuration, it is possible to provide a battery forklift capable of realizing deceleration or braking according to the accelerator operation amount. Therefore, for example, when going down a slope, it is possible to go down the slope at a speed according to the accelerator operation amount regardless of the load, and when climbing the slope, on the contrary, it is possible to climb smoothly without performing side alignment as in the past. it can.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment in which the present invention is applied to a counterbalance type forklift.
It will be described with reference to FIGS. However, FIG. 1 is a perspective view of a counterbalance type forklift, FIG. 2 is a block diagram of a control device, FIG. 3 is an operation explanatory view, and FIG. 4 is an operation explanatory flowchart.

The counterbalance type forklift according to this embodiment is constructed, for example, as shown in FIG. That is, a battery (not shown) is mounted and housed below the seat 2 provided in the driver's seat of the vehicle body 1, and the traveling motor and the hydraulic motor (neither motor is shown) are powered by this battery. These motors are driven, and in response to the depression of the accelerator pedal 3, the traveling motor is driven based on the output command value from the control device described later, and the traveling direction or the reverse direction is set by the tilting operation of the directional lever 4. The vehicle body 1 runs. Incidentally, 5 is a steering handle and 6 is a foot brake pedal.

Further, as shown in FIG. 1, a mast 8 is attached to the front portion of the vehicle body 1 so as to extend and contract, and a pair of L-shaped forks 10 are attached to the mast 8 via a lift bracket 9.
Is attached. Then, by operating the lift lever 12 provided in the driver's seat, the hydraulic motor is driven based on the output command value from the control device, the lift cylinder operates, and the mast 8 expands and contracts. Moves up and down. In addition to a lift lever 12, a tilt lever 14 is provided in the driver's seat, and a tilt cylinder is operated by the operation of the tilt lever 14, the mast 8 is tilted, and the fork 10 is tilted together with the mast 8. To do.

Further, as shown in FIG. 1, the driver's seat is provided with a limiting pedal 16 which constitutes an operating portion and is operated by the left foot for torque limiting operation. The operating amount (stepping amount) of the limiting pedal 16 is provided. Is detected by a detector (not shown in FIG. 1) including, for example, a potentiometer.

Next, the configuration of the control device will be described with reference to the block diagram of FIG. As shown in FIG. 2, the depression amount (operation amount) of the accelerator pedal 3 is detected by an accelerator sensor 22 including, for example, a potentiometer, and a target speed corresponding to the depression amount detected by the accelerator sensor 22 is derived by the CPU 21. The actual traveling speed is obtained by the CPU 21 from the rotation speed of the traveling motor 24 detected by the pulse generator 23 serving as a rotation detection unit, and the traveling motor 24 is adjusted so that the obtained traveling speed matches the target speed by the PID control. The instruction torque of PW is derived, and the PW is calculated according to the derived instruction torque.
The M inverter 25 is controlled to control the output of the traveling motor 24. However, the actual traveling speed may be detected by the encoders provided on the wheels.

The target speed derivation process by the CPU 21 corresponds to the target speed derivation unit of the present invention, and the instruction torque derivation process corresponds to the torque derivation unit of the present invention.

Further, as shown in FIG.
The depression amount of the limit pedal 16 detected by the detector 27 including a potentiometer provided in
Thus, when the derived instruction torque represents regeneration, the CPU 21 derives a limiting amount within a range from zero to a maximum value according to the depression amount of the limiting pedal 16 and gives an instruction based on this limiting amount. The maximum allowable torque is determined, the final allowable torque is derived, and the output control of the traveling motor 22 is performed according to the derived allowable torque. At this time, when the limit pedal 16 is not depressed, the limit amount for the instruction torque for regeneration becomes maximum and the allowable torque becomes zero or minimum, and when the limit pedal 16 is depressed, an instruction for regeneration is given. It is desirable to set the limit amount for torque to zero so that the allowable torque becomes maximum.

It should be noted that the CPU 21 determines whether or not the instruction torque represents regeneration based on the traveling direction of the vehicle body 1 set by the operation of the directional lever 4 and the polarity of the derived instruction torque. Specifically, in the graph showing the relationship between the instruction torque and the speed instruction shown in FIG.
If the quadrant is forward and the third quadrant is backward, if the polarity of the instruction torque is negative when the vehicle body 1 is in the forward state,
The instruction torque at that time is a torque indicating regeneration, and conversely, in reverse, if the polarity of the instruction torque is positive, it is determined that the instruction torque is a torque indicating regeneration.

As functions of the regenerative braking of the CPU 21, a downhill regenerative function for regenerating so as not to accelerate when descending, a neutral regenerating function for regenerating so as to coast when there is no accelerator operation, and a traveling direction of the vehicle body 1. There is a plugging regenerative function when switching is performed in the opposite direction, and a maximum speed regenerative function that performs regeneration at the maximum speed.
Calculates the regenerative torque required for regeneration in each of these regenerative functions based on, for example, the current motor rotation speed of the pulse generator 23, compares the calculated regenerative torque with the allowable torque, and adopts the one with the largest absolute value. Then, the output of the traveling motor 22 is controlled. Such a limiting process of the instruction torque by the CPU 21 corresponds to the control unit in the present invention.

Next, a series of operations will be described with reference to the flowchart of FIG. 4. First, as shown in FIG. 4, initial setting is performed (S1), and the CPU 21 causes the accelerator sensor 22 to depress the accelerator pedal 3. The amount and the operating direction of the directional lever 4 are fetched (S2), and the depression amount of the limit pedal 16 by the detector 27 is fetched (S3).

Then, the CPU 21 derives the target speed based on the taken in depression amount of the accelerator pedal 3 and the operation direction of the directional lever 4 (S).
4) The actual traveling speed is derived from the rotation speed of the traveling motor 24 detected by the pulse generator 23 (S
5) Then, the instruction torque of the traveling motor 24 is derived so that the actual traveling speed matches the target speed by the PID control (S6).

Thereafter, it is determined whether or not the derived instruction torque indicates regeneration (S7). If the determination result is YES, that is, if the instruction torque indicates regeneration, the limit pedal 16 by the detector 27 is determined. Based on the depression amount of step S6, the instruction torque derived in step S6 is limited to derive the permitting torque (S8), and the instruction torque or the permitting torque derived in step S6, whichever has a smaller absolute value, is used as the instruction torque. Adopted (S9), Downhill Regeneration,
Regenerative torques required for neutral regeneration, plugging regeneration, and maximum speed regeneration are calculated (S10), and each of the calculated regenerative torques and the instruction torque adopted in step S9 has a larger absolute value is adopted as the output torque ( S11), and then the process proceeds to step S13.

On the other hand, if the decision result in the above-mentioned step S7 is NO, that is, if the instructed torque does not indicate regeneration, the derived instructed torque is directly used as the output torque (S12), and then the process proceeds to step S13. Then
Output torque in step S11, or step S1
The output torque in 2 is output to the PWM inverter 25 as a torque command value to control the output of the traveling motor 24 (S13), and then the process returns to step S2.

Therefore, according to the above embodiment, the CP
When it is determined by U21 that the derived instruction torque represents regeneration, the instruction torque is limited according to the depression amount of the limit pedal 16 to derive the permission torque, and the output of the traveling motor 24 is controlled. It is possible to perform deceleration or braking according to the depression amount of the accelerator pedal 3.

As a result, for example, when going down a slope, if the limit pedal 16 is depressed, a constant braking force can be generated irrespective of the load without fully depressing the foot brake pedal 6, so that the accelerator pedal 3 The vehicle body 1 can be easily controlled to a desired speed according to the amount of depression.

When climbing a slope, the limit pedal 1
If the allowable torque is optimally limited by adjusting the amount of depression in step 6, the vehicle body 1 can climb uphill without slipping even if the side braking and the accelerator are not aligned as in the conventional case. it can.

Further, if the limit pedal 16 is fully depressed when stopping on the way of a slope, even if the side brake or the foot brake pedal 6 is not operated,
By stopping the depression of the accelerator pedal 3, the vehicle body 1 can be stopped without sliding down.

Also, when traveling on a flat road,
If the driver wishes to continue traveling as he or she prefers, the allowable torque becomes zero unless the limit pedal 16 is depressed, and the vehicle body 1 coasts on a flat road when the accelerator pedal 3 is stopped. Therefore, the driver can drive with the same driving feeling as before, without feeling any discomfort.

In the above-described embodiment, the case where the permission torque is set to zero or the minimum when the limit pedal 16 is not depressed and the permission torque is maximized when the limit pedal 16 is depressed will be described. However, conversely, when the limit pedal 16 is not depressed, the allowable torque becomes maximum and the limit pedal 16
Needless to say, the permission torque may be set to zero or the minimum when the pedal is depressed.

Further, in the above-described embodiment, the case where the four functions of the descending slope regeneration function, the neutral regeneration function, the plugging regeneration function, and the maximum speed regeneration function are provided has been described, but it is not always necessary to provide these four regeneration functions. Any function having at least three functions of the downhill regeneration function, the neutral regeneration function, and the plugging regeneration function may be used.

Further, in the above-described embodiment, the case where the present invention is applied to the counterbalance type forklift has been described. However, the range of application of the present invention other than the counterbalance type forklift is other reach type forklifts and other forklifts. Needless to say, the present invention can be applied to other electric vehicles in general, such as an electric vehicle, and in this case, the same effect as that of the above-described embodiment can be obtained.

In particular, when the present invention is applied to a standing type such as a reach type forklift, due to the structure of the standing type, the allowable torque becomes maximum when the operation device such as the limiting pedal 16 is not operated, and the limiting pedal 16 is used. It is preferable that the allowable torque is set to zero or minimum when operating the operating device such as.

The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention.

[0045]

As described above, according to the first aspect of the present invention, when the control unit determines that the torque instructed by the torque derivation unit represents the regeneration, the limit according to the operation of the operation unit. Is added to the instruction torque to control the output of the traveling motor.Therefore, even when the accelerator operation is stopped midway on a slope, a limit is applied to maximize the instruction torque for regeneration by operating the operating section. With this setting, it is possible to prevent the vehicle body from slipping down by maintaining the accelerator-free state, that is, the stopped state where the speed becomes zero.
Therefore, it is possible to provide an electric vehicle capable of performing deceleration or braking according to the accelerator operation amount.

According to the second aspect of the invention, it is possible to accurately determine whether or not the instructed torque represents regeneration.

According to the third aspect of the invention, the regenerative torque required for each of the downhill regenerative function, the neutral regenerative function, and the plugging regenerative function and the command torque after the limit has the largest absolute value. Since it is used to control the output of the traveling motor, regenerative braking when the instruction torque limit is zero, that is, when the instruction torque is not limited, and regeneration when the instruction torque is limited, are set according to the driver's preference. Braking can be selected according to the driver's preference, and it is possible to realize driving that is comfortable for the driver.

Further, according to the invention described in claim 4, since the limit amount of the instructed torque can be controlled by operating the pedal with the foot, it is suitable for the vehicle in which the driver sits on the seat and drives. Therefore, it becomes possible to provide a sitting operation type electric vehicle capable of performing deceleration or braking according to the accelerator operation amount.

According to the invention described in claim 5, since the limit amount of the instruction torque can be controlled by manually operating the operating device, it is suitable for a vehicle in which a driver stands up and drives. It is possible to provide a standing-type electric vehicle that can perform deceleration or braking according to the accelerator operation amount.

According to the sixth aspect of the present invention, the operation amount of the pedal or the operating device can be reliably detected by the detector, and the deceleration or braking according to the accelerator operation amount can be realized. become.

Further, according to the invention of claim 7, the smaller the amount of operation of the operating portion, the greater the degree of limitation applied to the instruction torque. Therefore, the allowable value of the instruction torque for regenerating the traveling motor is increased. Becomes smaller and regenerative braking is weakened. On the contrary, when the operation amount of the operation unit is large, the regenerative braking is strengthened. Therefore, the driver can operate the operation unit with a feeling similar to that of a general mechanical brake.

According to the eighth aspect of the invention, for example, if the limit applied to the instruction torque is maximum when the operation amount is maximum and the limit applied to the instruction torque is zero when the operation amount is zero, The limit applied to the instruction torque is zero immediately after the accelerator operation is stopped, that is, regenerative braking is applied at the maximum instruction torque, so the vehicle body does not slip even if the side brake is not operated even on the slope, even immediately after the accelerator operation is stopped. It becomes possible to prevent falling.

According to the ninth aspect of the invention, it is possible to provide a battery forklift capable of realizing deceleration or braking according to the accelerator operation amount.

[Brief description of drawings]

FIG. 1 is a perspective view of a counterbalanced forklift according to an embodiment of the present invention.

FIG. 2 is a block diagram of a control device according to an embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation of the embodiment of the present invention.

[Explanation of symbols]

1 Vehicle Body 3 Accelerator Pedal 16 Pedal (Operating Unit) 21 CPU (Target Speed Derivation Unit, Torque Derivation Unit, Control Unit) 22 Accelerator Sensor 23 Pulse Generator (Rotation Detection Unit) 24 Travel Motor 27 Detector

Claims (9)

[Claims] 1. An electric vehicle comprising: a battery mounted on a vehicle body; and a traveling motor that uses the battery as a drive source to generate an output torque according to an operation amount of an accelerator, and performs braking by regenerative braking of the traveling motor. In the control device, a target speed derivation unit that derives a target speed according to the operation amount of the accelerator, a rotation detection unit that detects a rotation speed of the traveling motor, and a detection speed by the rotation detection unit becomes the target speed. A torque derivation unit that derives such an instruction torque, an operation unit that applies a desired limit to the instruction torque, and a response to the operation of the operation unit when the instruction torque by the torque derivation unit represents regeneration. A control unit for controlling the output of the traveling motor by applying a limit to the command torque, and a control device for an electric vehicle. 2. The control of the electric vehicle according to claim 1, wherein the control unit determines whether the instructed torque represents regeneration based on a traveling direction of the vehicle body and a polarity of the instructed torque. apparatus. 3. The control unit at least includes a downhill regenerating function for regenerating so as not to accelerate when descending a downhill, a neutral regenerating function for regenerating so as to coast when there is no accelerator operation, and a traveling direction of the vehicle body. A plugging regenerative function when switching in the opposite direction is provided, the regenerative torque required in each of these regenerative functions is derived, and the one with the largest absolute value of the command torque after the limitation and the regenerative torque is adopted and the running is performed. The control device for an electric vehicle according to claim 1 or 2, which controls an output of the motor. 4. The control device for an electric vehicle according to claim 1, wherein the operation unit includes a pedal operable by a foot. 5. The control device for an electric vehicle according to claim 1, wherein the operation unit includes an operation device that can be operated by hand. 6. The control device for an electric vehicle according to claim 1, wherein the operation unit includes a detector that detects an operation amount of the operation unit. 7. The electric device according to claim 6, wherein the control unit increases the degree of restriction applied to the instruction torque as the operation amount of the operation unit detected by the detector decreases. Vehicle control device. 8. The electric device according to claim 6, wherein the control unit increases the degree of restriction applied to the instruction torque as the operation amount of the operation unit detected by the detector increases. Vehicle control device. 9. The control device for an electric vehicle according to claim 1, wherein the electric vehicle is a battery forklift.