Hybrid vehicle

Abstract

To continue providing assist control even when a SOC of a battery is low.SOLUTION: A hybrid vehicle may comprise: an engine; a first motor generator connected to the engine; a second motor generator connected to at least one drive wheel; a battery connected to the first and second motor generators; a parking lock mechanism which mechanically prohibits rotation of the drive wheel; and a control device which can perform assist control in a manner that drives the second motor generator and assists operation to release parking lock when the parking lock mechanism release the parking lock. The control device may drive the engine to cause the first motor generator to generate electricity when a SOC of the battery falls below a threshold while the assist control is in execution.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to hybrid vehicles. [Background technology]

[0002] Patent Document 1 discloses a hybrid vehicle. This hybrid vehicle includes a motor generator, a gear unit having a parking lock mechanism, and a control device capable of executing assist control that drives the motor generator to assist the release operation when the parking lock mechanism is released. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-286312 Summary of the Invention [Problem to be solved by the invention]

[0004] In the hybrid vehicle described above, the assist control is executed by supplying power from the battery to the motor generator. Therefore, if the SOC (State Of Charge) of the battery decreases while the assist control is being executed, there is a possibility that the assist control cannot be continued in order to avoid over-discharging of the battery.

[0005] In view of the above-mentioned problems, the present specification provides a technique that can continue assist control even when the SOC of the battery decreases. [Means for solving the problem]

[0006] The hybrid vehicle disclosed in this specification includes an engine, a first motor generator connected to the engine, a second motor generator connected to at least one drive wheel, a battery connected to the first motor generator and the second motor generator, a parking lock mechanism that mechanically prohibits rotation of the drive wheels, and a control device capable of executing assist control that drives the second motor generator to assist the release operation when the parking lock mechanism is released. When the SOC of the battery falls below a threshold during the execution of the assist control, the control device drives the engine to cause the first motor generator to generate electricity.

[0007] In the hybrid vehicle described above, when the SOC of the battery falls below a threshold value while the assist control is being executed, the control device drives the engine to cause the first motor generator to generate electricity. The generated power by the first motor generator is supplied to the battery (and the second motor generator) to restore the SOC of the battery. This allows the assist control to be continued even if the SOC of the battery drops while the assist control is being executed. [Brief description of the drawings]

[0008] [Figure 1] 1 shows a schematic diagram of a hybrid vehicle according to an embodiment of the present invention. [Diagram 2] 3 shows a flowchart of a series of processes executed by a control device. [Diagram 3] 4 shows a time chart relating to assist control of the release operation of the parking lock mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

[0009] A hybrid vehicle 10 according to the embodiment will be described with reference to the drawings. The hybrid vehicle 10 according to the embodiment belongs to an electric vehicle having a motor for driving wheels, and is typically an electric vehicle (so-called automobile) that runs on a road surface. However, some or all of the technology described in the embodiment can be similarly adopted in an electric vehicle that runs on a track. The hybrid vehicle 10 includes a vehicle body 12, a pair of front wheels 14 provided at the front of the vehicle body 12, and a pair of rear wheels 16 provided at the rear of the vehicle body 12. Note that the specific configuration of the vehicle body 12 and the number of wheels provided on the hybrid vehicle 10 are not particularly limited. In addition, the hybrid vehicle 10 is not limited to one that is driven and operated by a user, and may be one that is remotely operated by an external device or one that runs autonomously.

[0010] The hybrid vehicle 10 further includes an engine 18, a transmission 19, a first motor generator (hereinafter referred to as the "first motor") 20, a second motor generator (hereinafter referred to as the "second motor") 22, a battery 24, and a gear unit 26. The engine 18 is a heat engine that generates power by burning fuel, and examples of the engine include, but are not limited to, a gasoline engine and a diesel engine.

[0011] The first motor 20 is mechanically connected to the engine 18 and functions as a generator. That is, the hybrid vehicle 10 can generate electricity by using the first motor 20 to drive the first motor 20 with the engine 18. The first motor 20 is electrically connected to a battery 24, and the electric power generated by the first motor 20 is supplied to the battery 24 to charge the battery 24. The engine 18 is mechanically connected to the second motor 22 via the transmission 19.

[0012] The second motor 22 is electrically connected to the battery 24 and operates by receiving power supply from the battery 24. The second motor 22 is mechanically connected to the front wheels 14 via a gear unit 26 and functions as a prime mover that drives the front wheels 14. That is, the rotational motion (i.e., torque) output by the second motor 22 is distributed to the pair of front wheels 14 via the gear unit 26. The second motor 22 can function not only as a prime mover but also as a generator for regenerative braking of the front wheels 14. That is, when the hybrid vehicle 10 needs to decelerate, the second motor 22 can function as a generator to perform regenerative braking of the front wheels 14. The second motor 22 may drive the rear wheels 16 as drive wheels instead of the front wheels 14.

[0013] The battery 24 is connected to the first motor 20 and the second motor 22. The battery 24 is a power supply device for the second motor 22 and supplies driving power to the second motor 22. The battery 24 has a plurality of secondary battery cells and is configured to be capable of repeated charging and discharging. The secondary battery cells referred to here are not particularly limited, and may be, for example, lithium ion battery cells or nickel metal hydride battery cells. Although not shown, power conversion devices may be provided between the battery 24 and the first motor 20 and between the battery 24 and the second motor 22, respectively, as necessary.

[0014] The transmission 19 is provided with a parking lock mechanism 28. The parking lock mechanism 28 has an engagement member (e.g., a parking lock pole) that engages / disengages with a rotating gear in the transmission 19, and is a mechanism that mechanically prohibits rotation of the transmission 19 (i.e., the front wheels 14). Usually, the parking lock mechanism 28 is used when the hybrid vehicle 10 is parked, and prevents unintended movement of the hybrid vehicle 10. The specific configuration of the parking lock mechanism 28 is not particularly limited, and for example, the one described in Patent Document 1 can be adopted. Note that the parking lock mechanism 28 may be provided in, for example, the gear unit 26 instead of the transmission 19.

[0015] The hybrid vehicle 10 further includes a control device 30. The control device 30 is configured using a computer device and has a processor, a memory, and the like. The control device 30 is electrically connected to the engine 18, the battery 24, and the gear unit 26, and is configured to be able to control the operations of these. For example, operation information by a user and vehicle information indicating the state of the hybrid vehicle 10 are input to the control device 30. The operation information is, for example, accelerator opening information indicating the amount of operation of the accelerator pedal by the user, and brake depression force information indicating the amount of brake operation by the user. The vehicle information is, for example, gradient information indicating the gradient of the hybrid vehicle 10 and battery information indicating the SOC of the battery 24. The control device 30 controls the operation of each part of the hybrid vehicle 10 described above according to the input operation information and vehicle information.

[0016] With reference to Fig. 2, a process related to assist control executed by the control device 30 when the parking lock mechanism 28 of the hybrid vehicle 10 is released will be described. The assist control is a process for assisting the release operation by driving the second motor 22 to reduce the applied load of the parking lock mechanism 28 when the parking lock mechanism 28 is released. The assist control is a well-known technique and is described in, for example, Patent Document 1. This process is started in response to a release operation of the parking lock mechanism 28 by the user.

[0017] First, in step S10, the control device 30 determines whether the parking lock mechanism 28 is in a locked state. If the control device 30 determines that the parking lock mechanism 28 is in a locked state (YES in step S10), the control device 30 proceeds to the process of step S12. On the other hand, if the control device 30 determines that the parking lock mechanism 28 is in an unlocked state (NO in step S10), the control device 30 executes the process of step S30.

[0018] In step S30, the control device 30 does not execute the assist control of the release operation of the parking lock mechanism 28. After that, the control device 30 executes the process of step S10 again.

[0019] In step S12, the control device 30 determines whether the hybrid vehicle 10 is inclined at a predetermined gradient or more. The control device 30 may determine the inclination of the hybrid vehicle 10 by, for example, referring to gradient information. When the control device 30 determines that the hybrid vehicle 10 is inclined at a predetermined gradient or more (YES in step S12), the control device 30 proceeds to the process of step S14. Although not shown, when the hybrid vehicle 10 is inclined at a predetermined gradient or more, the hybrid vehicle 10 attempts to move along the gradient, and a large engagement load is generated in the parking lock mechanism 28. In this case, there is a risk that the parking lock mechanism 28 will not be able to perform the release operation.

[0020] On the other hand, when the control device 30 determines that the vehicle body 12 is not inclined at a gradient equal to or greater than the predetermined gradient (NO in step S12), the control device 30 executes the process of step S30.

[0021] In step S14, the control device 30 determines whether the foot brake is operated (ON). The control device 30 may determine whether the foot brake is operated by, for example, referring to brake depression force information. If the control device 30 determines that the foot brake is operated (YES in step S14), it proceeds to the process of step S16. On the other hand, if the control device 30 determines that the foot brake is released (OFF) (NO in step S14), it executes the process of step S30.

[0022] In step S16, the control device 30 determines whether the SOC of the battery 24 exceeds a threshold A%. The threshold A% may be set, for example, taking into consideration the power consumption of the second motor 22. When the control device 30 determines that the SOC of the battery 24 exceeds A% (YES in step S16), the control device 30 does not drive the first motor 20 in step S18, and executes assist control of the parking lock release operation in step S22. That is, the control device 30 assists the release operation of the parking lock mechanism 28 by supplying drive power from the battery 24 to the second motor 22 without driving the first motor 20.

[0023] On the other hand, when the control device 30 determines that the SOC of the battery 24 is equal to or lower than the threshold value A % (NO in step S16), the process proceeds to step S20.

[0024] In step S20, the control device 30 drives the engine 18 to generate power from the first motor 20. The power generated by the first motor 20 is supplied to the battery 24, and the SOC of the battery 24 is restored.

[0025] Next, in step S22, the control device 30 assists the release operation of the parking lock mechanism 28 by supplying driving power from the battery 24 whose SOC has recovered to the second motor 22. After the process of step S22, the control device 30 returns to the process of step S10 and repeats the series of processes described above.

[0026] As described above, when the SOC of the battery 24 falls below the threshold A% during and before the assist control is executed, the control device 30 drives the engine 18 to cause the first motor 20 to generate electricity. The generated power by the first motor 20 is supplied to the battery 24 and the second motor 22 to restore the SOC of the battery 24. This makes it possible to continue the assist control even if the SOC of the battery 24 drops during the execution of the assist control.

[0027] Next, an example of the operation of the hybrid vehicle 10, particularly the operation related to the assist control of the release operation of the parking lock mechanism 28 by the control device 30, will be described with reference to FIG.

[0028] Graph (A) in FIG. 3 shows the change over time in the SOC of the battery 24. A in FIG. 3 shows the threshold A%. Graph (B) shows the state of the foot brake applied by the user. Graph (C) shows the state of the parking lock mechanism 28. When graph (C) is ON, it indicates that the parking lock mechanism 28 is in a locked state, and when graph (C) is OFF, it indicates that the parking lock mechanism 28 is in an unlocked state. Graph (D) shows the change over time in the output power of the second motor 22. Graph (E) shows the change over time in the output power of the first motor 20.

[0029] At time t0, the parking lock mechanism 28 of the hybrid vehicle 10 is in a locked state (YES in step S10 in FIG. 3), and the hybrid vehicle 10 is tilted at a gradient equal to or greater than a predetermined gradient (YES in step S12).

[0030] At time t1, it is assumed that the user operates the foot brake (ON) (YES in step S14). At this time, the SOC of the battery 24 exceeds the threshold A% (YES in step S16), so that driving power is supplied from the battery 24 to the second motor 22, and assist control is executed to assist the release operation of the parking lock mechanism 28 (steps S18, S22).

[0031] At time t2, when the SOC of the battery 24 becomes equal to or lower than the threshold A% (NO in step S20), the engine 18 is driven to cause the first motor 20 to generate power. The generated power by the first motor 20 is supplied to the battery 24, and the SOC of the battery 24 is restored (from time t2 to t3). This makes it possible to continue the assist control even if the SOC of the battery 24 drops during execution of the assist control.

[0032] At time t3, when the release operation of the parking lock mechanism 28 is completed and the parking lock mechanism 28 is in an unlocked state, the assist control is stopped (NO in step S10, S18).

[0033] In this embodiment, the hybrid vehicle 10 is a vehicle having a so-called series type hybrid mechanism, but the type of the hybrid mechanism is not particularly limited. For example, the hybrid vehicle 10 may be a vehicle having a parallel type hybrid mechanism, in which at least a part of the power of the engine is mechanically transmitted to the output shaft of the drive wheels, and, if necessary, the power of at least one motor generator may also be transmitted to the output shaft. [Explanation of symbols]

[0034] 10: hybrid vehicle, 12: vehicle body, 14: front wheels, 16: rear wheels, 18: engine, 19: transmission, 20: first motor generator, 22: second motor generator, 24: battery, 26: gear unit, 28: parking lock mechanism, 30: control device, A: threshold value

Claims

[Claim 1] A hybrid vehicle, The engine, a first motor generator connected to the engine; A second motor generator connected to at least one driving wheel; a battery connected to the first motor generator and the second motor generator; a parking lock mechanism that mechanically prohibits rotation of the drive wheels; a control device capable of executing an assist control for driving the second motor generator during a release operation of the parking lock mechanism to assist the release operation; Equipped with the control device drives the engine to cause the first motor generator to generate power when an SOC of the battery falls below a threshold during execution of the assist control. Hybrid car.

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