JP2023183560A - drive unit - Google Patents

Abstract

To suppress a driving feeling from lowering at the time of deceleration.SOLUTION: A drive unit 100 includes an electric motor 2, an electromagnetic brake 3 and a controlling unit 4. The electromagnetic brake 3 is mounted on the electric motor 2. The controlling unit 4 is configured to control the electromagnetic brake 3. The controlling unit 4 is configured to control the electromagnetic brake 3 according to a vehicle speed when determining that deceleration operation is performed.SELECTED DRAWING: Figure 1

Description

The present invention relates to a drive unit.

A riding vehicle such as a riding mower or a golf cart has an engine and an HST (Hydraulic Static Transmission). This riding work vehicle can decelerate using HST, so it does not have a foot brake for deceleration.

2. Description of the Related Art In recent years, electric type riding work vehicles that use an electric motor as a drive source have been proposed. This electric type passenger work vehicle does not have an HST and is decelerated by regenerative braking of an electric motor.

JP2017-6141A

In the above-mentioned electric type riding work vehicle, there is a problem in that when the vehicle is decelerated by regenerative braking during low-speed driving, torque fluctuation becomes large and driving feeling deteriorates.

An object of the present invention is to suppress deterioration in driving feeling during deceleration.

The drive unit according to the first aspect is configured to be mounted on a passenger work vehicle. This drive unit includes an electric motor, an electromagnetic brake, and a control section. An electromagnetic brake is attached to the electric motor. The control unit is configured to control the electromagnetic brake. The control unit is configured to control the electromagnetic brake according to the vehicle speed when it is determined that a deceleration operation has been performed.

According to this configuration, when a deceleration operation is performed at low speed, deceleration can be achieved by operating the electromagnetic brake without using the regenerative brake of the electric motor. As a result, it is possible to suppress torque fluctuations due to deceleration during low-speed running, and therefore it is possible to suppress deterioration in driving feeling during deceleration.

The drive unit according to the second aspect is configured as follows in the drive unit according to the first aspect. The control unit is configured to operate the electromagnetic brake when a deceleration operation is performed and the vehicle speed is determined to be below a threshold value.

The drive unit according to the third aspect is configured as follows in the drive unit according to the first or second aspect. The control unit is configured to calculate an excitation current to be supplied to the electromagnetic brake based on the operation amount input to the operation unit.

The drive unit according to the fourth aspect is configured as follows in the drive unit according to the third aspect. The control unit is configured to supply the upper limit excitation current to the electromagnetic brake when determining that the calculated excitation current is larger than the upper limit excitation current. Note that the upper limit excitation current is predetermined for each vehicle speed.

The drive unit according to the fifth aspect is configured as follows in the drive unit according to any one of the first to fourth aspects. The control unit operates the electromagnetic brake when determining that the passenger work vehicle is in a stopped state. According to this configuration, it is possible to maintain the stopped state of the riding work vehicle with less power consumption than when maintaining the stopped state of the riding work vehicle using an electric motor.

The drive unit according to the sixth aspect is configured as follows in the drive unit according to any one of the first to fifth aspects. The control section operates the electromagnetic brake when determining that the required deceleration torque is greater than the regenerative deceleration torque. The required deceleration torque is calculated based on the operation amount input to the operation section. Regenerative deceleration torque is deceleration torque generated by regenerative braking of the electric motor.

According to the present invention, it is possible to suppress a decrease in driving feeling during deceleration.

Block diagram of the drive unit. 5 is a flowchart for explaining a control method of a control unit. Flowchart for explaining stop processing. 5 is a flowchart for explaining first deceleration processing. 7 is a flowchart for explaining second deceleration processing of a control unit according to a modification. 7 is a flowchart for explaining second deceleration processing of a control unit according to a modification.

Hereinafter, the drive unit 100 according to the present embodiment will be described with reference to the drawings. The drive unit 100 is mounted on a passenger work vehicle that does not have a foot brake. The riding vehicle is, for example, a riding mower, a golf cart, or the like. A foot brake is a brake operated by a brake pedal to slow down a passenger work vehicle. Note that the passenger work vehicle may include a parking brake for maintaining the parked state. Further, the passenger work vehicle does not have an engine or an HST.

[Drive unit]
As shown in FIG. 1, the drive unit 100 includes an electric motor 2, an electromagnetic brake 3, and a control section 4. The drive unit 100 also includes a battery 5, an inverter 6, a drive circuit 7, and the like.

[Electric motor]
Electric motor 2 is connected to battery 5 . Specifically, electric motor 2 is connected to battery 5 via inverter 6 . The electric motor 2 is driven by power supplied from the battery 5. Moreover, the electric motor 2 can function as a generator. The electric power generated by the electric motor 2 is charged into the battery 5 .

[Electromagnetic brake]
The electromagnetic brake 3 is attached to the electric motor 2. For example, the electromagnetic brake 3 is attached to the output shaft of the electric motor 2. The electromagnetic brake 3 is connected to a battery 5. Specifically, the electromagnetic brake 3 is connected to the battery 5 via a drive circuit 7.

The electromagnetic brake 3 is configured to reduce the speed of the passenger work vehicle. Specifically, the electromagnetic brake 3 is configured to reduce the rotational speed of the electric motor 2. Further, the electromagnetic brake 3 is configured to maintain the stopped state of the riding work vehicle.

The electromagnetic brake 3 is an excitation actuation type brake. The electromagnetic brake 3 brakes the rotation of the output shaft of the electric motor 2 by being supplied with an excitation current from the battery 5 . The electromagnetic brake 3 generates a braking force (deceleration torque) according to the supplied excitation current. By increasing the excitation current supplied to the electromagnetic brake 3, the braking force (deceleration torque) by the electromagnetic brake 3 can be increased. Note that the deceleration torque is a torque for decelerating the riding work vehicle.

[Control unit]
The control unit 4 is configured to control the electromagnetic brake 3. The control unit 4 controls the electromagnetic brake 3 by controlling the excitation current supplied to the electromagnetic brake 3. Note that the control unit 4 controls the excitation current supplied to the electromagnetic brake 3 by controlling the drive circuit 7 .

Further, the control unit 4 is configured to control the electric motor 2. Specifically, the control unit 4 controls the electric motor 2 by controlling the inverter 6. Note that the control unit 4 performs speed control on the electric motor 2 rather than torque control.

The control unit 4 is configured by a computer (for example, a microcomputer) including, for example, a CPU (Central Processing Unit) and a ROM (Read Only Memory). The ROM stores programs for performing various calculations. The CPU executes programs stored in the ROM.

The control unit 4 is communicably connected to the speed sensor 11 and the forward/backward operation unit 12 (hereinafter also referred to as “operation unit 12”) by wire or wirelessly. The control unit 4 acquires data regarding the vehicle speed of the passenger work vehicle from the speed sensor 11. The control unit 4 receives a deceleration operation signal and data regarding the amount of operation from the operation unit 12 .

Note that the operating unit 12 is, for example, an operating lever or an operating pedal. The operation unit 12 is operated by the driver when a deceleration request or an acceleration request is made. The operating unit 12 is operated forward and backward around the neutral position. When the driver operates the operation unit 12 from the neutral position toward the front or rear, the riding work vehicle can be accelerated in the forward or backward direction. Note that operating the operating portion 12 from the neutral position toward the front or rear is referred to as an acceleration operation. On the other hand, the rider can decelerate the riding work vehicle by operating the operation unit 12 from the front or rear toward the neutral position. Note that operating the operating portion 12 from the front or rear toward the neutral position is referred to as a deceleration operation. When this deceleration operation is performed, the control unit 4 receives the deceleration operation signal and determines that the deceleration operation has been performed. Further, by the driver holding the operating unit 12 in the neutral position, the riding work vehicle can be maintained in a stopped state. In the following description, unless otherwise specified, the amount of operation means the amount of operation when the operation unit 12 is operated to decelerate.

The control unit 4 stores an excitation current map and an upper limit current map. The excitation current map and the upper limit current map are created in advance and stored in the control unit 4. The excitation current map is a map that associates the operation amount with the excitation current supplied to the electromagnetic brake 3. This excitation current map shows how much excitation current should be supplied to the electromagnetic brake 3 in response to the amount of operation when the driver operates the operation unit 12. Note that in the excitation current map, as the manipulated variable increases, the excitation current also increases. That is, the larger the operation amount, the larger the deceleration torque by the electromagnetic brake 3. When the driver operates the operation unit 12, the control unit 4 calculates an excitation current corresponding to the amount of operation based on an excitation current map, and causes the battery 5 to supply the calculated excitation current to the electromagnetic brake 3. .

Note that the control unit 4 may have a deceleration torque map and a second excitation current map instead of this excitation current map. The deceleration torque map is a map that associates the operation amount with the deceleration torque. The second excitation current map is a map that associates deceleration torque with excitation current. In this case, the control unit 4 first calculates the deceleration torque according to the operation amount based on the deceleration torque map. Then, the control unit 4 calculates the excitation current necessary for causing the electromagnetic brake 3 to generate the deceleration torque based on the second excitation current map.

The upper limit current map is a map that associates vehicle speed with excitation current. In this upper limit current map, an excitation current represents the upper limit of deceleration that is allowable at the vehicle speed when a deceleration operation is performed. That is, the upper limit current map indicates the upper limit excitation current that is preset for each vehicle speed. Note that in the upper limit current map, as the vehicle speed increases, the excitation current also increases.

The control unit 4 is configured to execute a stop process and a first deceleration process. When the control unit 4 determines that the riding work vehicle is in a stopped state, it executes a stopping process. The control unit 4 controls the drive circuit 7 so that a constant excitation current is supplied to the electromagnetic brake 3 in the stop process.

The control unit 4 controls the electromagnetic brake 3 according to the vehicle speed. Specifically, when the control unit 4 receives the deceleration operation signal and determines that the vehicle speed at that time is less than or equal to the threshold value, the control unit 4 executes the first deceleration process. In the first deceleration process, the control unit 4 supplies the electromagnetic brake 3 with the excitation current calculated based on the excitation current map. Note that the control unit 4 does not operate the regenerative brake by the electric motor 2 in the first deceleration process.

[Control method]
Next, a method of controlling the electromagnetic brake by the control section 4 will be explained. FIG. 2 is a flowchart for explaining the control method of the control unit 4, FIG. 3 is a flowchart for explaining the stop processing, and FIG. 4 is a flowchart for explaining the first deceleration processing.

As shown in FIG. 2, the control unit 4 determines whether the passenger work vehicle is stopped (step S1). For example, the control unit 4 determines whether the riding work vehicle is stopped based on data regarding the speed acquired from the speed sensor 11.

When the control unit 4 determines that the passenger work vehicle is stopped (Yes in step S1), it executes a stop process (step S2). That is, the control unit 4 controls the drive circuit 7 so that a constant excitation current is supplied to the electromagnetic brake 3.

Specifically, as shown in FIG. 3, the control unit 4 supplies a constant excitation current (stop holding current) to the electromagnetic brake 3 (step S21). Next, the control unit 4 determines whether there is a request to cancel the stoppage (step S22). For example, when an acceleration operation is performed, the control unit 4 determines that a request to cancel the stop has been made.

When the control unit 4 determines that there is a release request (Yes in step S22), it stops supplying the excitation current to the electromagnetic brake 3 (step S23). As a result, the braking by the electromagnetic brake 3 is released. On the other hand, if the control unit 4 determines that there is no cancellation request (No in step S22), the process returns to step S21 again.

As shown in FIG. 2, when the control unit 4 determines that the passenger car is not stopped (No in step S1), it next determines whether a deceleration operation has been performed (step S3). If the control unit 4 determines that a deceleration operation has not been performed (No in step S3), the process returns to step S1 again.

When the control unit 4 determines that a deceleration operation has been performed (Yes in step S3), it then determines whether the vehicle speed is less than or equal to a threshold value (step S4). When the control unit 4 determines that the vehicle speed is less than or equal to the threshold value (Yes in step S4), it executes the first deceleration process (step S5).

Specifically, as shown in FIG. 4, the control unit 4 first outputs a regeneration prohibition instruction (step S51). Specifically, the control unit 4 controls the inverter 6 so that the regenerative brake by the electric motor 2 is not activated.

Next, the control unit 4 calculates the excitation current based on the manipulated variable and the excitation current map (step S52). Specifically, the control unit 4 determines the excitation current corresponding to the operation amount of the deceleration operation based on the excitation current map.

Subsequently, the control unit 4 determines whether the calculated excitation current is greater than or equal to the upper limit excitation current (step S53). Specifically, the control unit 4 calculates the upper limit excitation current based on the vehicle speed and the upper limit current map. That is, the control unit 4 determines the upper limit excitation current corresponding to the current vehicle speed based on the upper limit current map.

When the control unit 4 determines that the calculated excitation current is equal to or higher than the upper limit excitation current (Yes in step S53), it controls the drive circuit 7 so that the upper limit excitation current is supplied to the electromagnetic brake 3 ( Step S54).

On the other hand, if the controller 4 determines that the calculated excitation current is less than the upper limit excitation current (No in step S53), the controller 4 controls the drive so that the excitation current calculated in step S52 is supplied to the electromagnetic brake 3. The circuit 7 is controlled (step S55).

As shown in FIG. 2, when the control unit 4 determines that the vehicle speed is greater than the threshold (No in step S4), it executes the second deceleration process (step S6). Note that the control unit 4 does not operate the electromagnetic brake 3 in the second deceleration process. That is, the control unit 4 controls the inverter 6 so that the regenerative brake of the electric motor 2 is activated.

[Modified example]
Although the embodiments of the present invention have been described above, the present invention is not limited to these, and various changes can be made without departing from the spirit of the present invention. Note that the following modifications can basically be applied at the same time.

(a) In the above embodiment, the control unit 4 controls the electromagnetic brake 3 not to operate in the second deceleration process, but the invention is not limited to this. That is, the control unit 4 may operate the electromagnetic brake 3 in the second deceleration process. The second deceleration process in this modification will be described below.

As shown in FIG. 5, the control unit 4 calculates the required deceleration torque based on the operation amount (step S101). For example, the control unit 4 has a deceleration torque map that is a map that associates operation amounts with deceleration torques. The control unit 4 calculates the necessary deceleration torque according to the operation amount based on the deceleration torque map.

Next, the control unit 4 determines whether the required deceleration torque is less than or equal to the regenerative deceleration torque caused by the regenerative brake of the electric motor 2 (step S102). Note that the control unit 4 calculates the regenerative deceleration torque based on the motor performance of the electric motor 2, the charging rate (SOC) of the battery 5, the motor rotation speed, and the like.

When the control unit 4 determines that the required deceleration torque is less than or equal to the regenerative deceleration torque (Yes in step S102), the controller 4 decelerates the electric motor 2 only by using the regenerative brake (step S103). That is, the control unit 4 does not operate the electromagnetic brake 3.

On the other hand, if the control unit 4 determines that the required deceleration torque is larger than the regenerative deceleration torque (No in step S102), the control unit 4 operates the electromagnetic brake 3 in addition to the regenerative brake of the electric motor 2 ( Step S104). Specifically, the control unit 4 causes the electromagnetic brake 3 to generate insufficient deceleration torque, which is obtained by subtracting the regenerative deceleration torque from the necessary deceleration torque. The control unit 4 supplies an excitation current corresponding to the insufficient deceleration torque to the electromagnetic brake 3 based on the second excitation current map.

(b) In the second deceleration process, the control unit 4 may operate the electromagnetic brake 3 as follows depending on the conditions.

As shown in FIG. 6, the control unit 4 determines whether there is a disadvantageous regenerative braking condition (step S201). That is, the control unit 4 determines whether the condition is such that the regenerative brake by the electric motor 2 is not sufficiently activated. For example, the control unit 4 compares the current Id used for field weakening of the electric motor 2 and the torque current Iq of the electric motor 2, and if it determines that the current Id>current Iq, it determines that the regenerative braking disadvantageous condition exists. to decide. Further, when the control unit 4 determines that a deceleration operation has been performed while traveling uphill based on the vehicle speed and the amount of operation, it also determines that the regenerative braking disadvantageous condition exists. Further, when the control unit 4 determines that the charging rate (SOC) of the battery 5 is equal to or higher than the threshold value, the control unit 4 also determines that the regenerative braking disadvantageous condition exists.

If the control unit 4 determines that the regenerative brake is disadvantageous (Yes in step S201), it operates the electromagnetic brake 3 in addition to the regenerative brake of the electric motor 2 (step S202). On the other hand, if the control unit 4 determines that there is no disadvantageous condition for regenerative braking (No in step S201), the controller 4 decelerates the vehicle only by using the regenerative brake of the electric motor 2 (step S203). That is, the control unit 4 does not operate the electromagnetic brake 3.

(c) In the embodiment described above, the control unit 4 calculates the excitation current based on the manipulated variable, but the method of calculating the excitation current by the control unit 4 is not limited to this. For example, the control unit 4 may calculate the excitation current by considering not only the amount of operation but also the operation speed. For example, the control unit 4 may calculate the excitation current such that the faster the operation speed is, the larger the excitation current is.

2: Electric motor 3: Electromagnetic brake 4: Control section 12: Operation section 100: Drive unit

Claims (6)

A drive unit configured to be mounted on a passenger work vehicle,
electric motor and
an electromagnetic brake attached to the electric motor;
a control unit configured to control the electromagnetic brake;
Equipped with
The control unit is configured to control the electromagnetic brake according to vehicle speed when determining that a deceleration operation has been performed.
drive unit.
The control unit is configured to operate the electromagnetic brake when a deceleration operation is performed and the vehicle speed is determined to be below a threshold value.
The drive unit according to claim 1.
The control unit is configured to calculate an excitation current to be supplied to the electromagnetic brake based on the operation amount input to the operation unit.
The drive unit according to claim 2.
The control unit is configured to supply the upper limit excitation current to the electromagnetic brake when determining that the calculated excitation current is larger than an upper limit excitation current predetermined for each vehicle speed.
The drive unit according to claim 3.
The control unit operates the electromagnetic brake when determining that the riding work vehicle is in a stopped state.
The drive unit according to claim 1.
The control unit operates the electromagnetic brake when determining that the required deceleration torque calculated based on the operation amount input to the operation unit is larger than the regenerative deceleration torque caused by the regenerative brake of the electric motor.
The drive unit according to claim 1.

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