Control system for hybrid vehicles

Abstract

To avoid or reduce incomplete warm-up of an engine in a hybrid vehicle.SOLUTION: A control device executes processing of counting the number of times that the hybrid vehicle is started and stopped before warm-up of an engine is completed as the number of times of incomplete warm-up. In addition, when the hybrid vehicle is started, the control device executes processing of setting at least one of a start threshold and a stop threshold for the engine in accordance with the counted number of times of incomplete warm-up. In addition, the control device executes processing of starting the engine when a request output for the engine exceeds the set start threshold and stopping the engine when the request output falls below the set stop threshold. When a predetermined time elapses after warm-up of the engine is completed with the hybrid vehicle started, the control device executes processing of subtracting or clearing the counted number of times of incomplete warm-up.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology disclosed in this specification relates to a control device for a hybrid vehicle.

Background Art

[0002] Patent Document 1 describes a technology related to the warm-up of an engine mounted on a vehicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of a hybrid vehicle, the start and stop of the engine are repeated according to the required output for the engine. Therefore, the time required for engine warm-up becomes relatively long, and the use of the hybrid vehicle may end before the engine warm-up is completed. Such incomplete warm-up may have an adverse effect on the engine etc. (including oil and fuel).

[0005] In view of the above, this specification provides a technology that can avoid or suppress incomplete warm-up of the engine in a hybrid vehicle.

Means for Solving the Problems

[0006] The technology disclosed herein is embodied in a control device for a hybrid vehicle. The control device performs a process to count the number of times the hybrid vehicle is started and stopped (also referred to as ready-off) before the engine warm-up is complete as the number of incomplete warm-ups. In addition, when the hybrid vehicle is started, the control device performs a process to set at least one of the engine start threshold and stop threshold according to the counted number of incomplete warm-ups. In addition, the control device performs a process to start the engine when the requested output for the engine exceeds the set start threshold, and to stop the engine when the requested output falls below the set stop threshold. When a predetermined time has elapsed since the engine warm-up was complete while the hybrid vehicle is running, the control device performs a process to subtract or clear the counted number of incomplete warm-ups.

[0007] In the configuration described above, the control device can change the conditions related to engine starting / stopping (i.e., the starting threshold and / or stopping threshold) according to the number of times the engine has not been fully warmed up. For example, if the number of times the engine has not been fully warmed up is high, the control device can adjust each threshold so as to lower the starting threshold for the engine or raise the stopping threshold for the engine. This can increase the number of times the engine is started and the starting time, thereby accelerating engine warm-up. On the other hand, if, for example, the user's usage of the hybrid vehicle changes, the starting threshold and / or stopping threshold adjusted according to the previous usage may become excessive for the new usage. Therefore, the control device is configured to subtract or clear the counted number of times the engine has not been fully warmed up if the hybrid vehicle continues to be used for a predetermined period of time after the engine has warmed up. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing the configuration of a hybrid vehicle. [Figure 2] This flowchart shows an example of a series of processing steps performed by a control device. [Figure 3]This diagram illustrates the starting threshold. [Modes for carrying out the invention]

[0009] Referring to the drawings, the control device 30 of the hybrid vehicle 10 in this embodiment will be described. A hybrid vehicle is a vehicle whose wheels are driven by the power of an engine and a drive motor. In this embodiment, the control device 30 is mounted on the hybrid vehicle 10. However, in other embodiments, the control device 30 does not have to be mounted on the hybrid vehicle 10, but may be located outside the hybrid vehicle 10 and controlled remotely.

[0010] As shown in Figure 1, the hybrid vehicle 10 (hereinafter simply referred to as vehicle 10) includes, in addition to the control device 30 described above, a vehicle body 12, a plurality of wheels 14, 16, an engine 18, a first motor 20, a second motor 22, a power split mechanism 24, a gear unit 26, a battery 28, and a temperature sensor 32. The plurality of wheels 14, 16 include 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. The specific configuration of the vehicle body 12 and the number of wheels provided by vehicle 10 are not particularly limited.

[0011] The engine 18 is a heat engine that generates power by burning fuel, and is not particularly limited, but examples include gasoline engines and diesel engines. A temperature sensor 32 is located near the engine 18. The temperature sensor 32 is a sensor for monitoring the temperature of the engine 18, and specifically detects the temperature of the coolant used to cool the engine 18. The coolant circulates through a cooling path that passes through the engine 18 and a radiator (not shown).

[0012] The power split mechanism 24 is mechanically connected to the engine 18. The power split mechanism 24 is mechanically connected to the first motor 20 and the second motor 22. The power split mechanism 24 distributes the power of the engine 18 to the first motor 20 and the second motor 22 (i.e., the pair of front wheels 14).

[0013] The first motor 20 is mechanically connected to the engine 18 via a power split mechanism 24 and functions as a generator. That is, the hybrid vehicle 10 can generate electricity by driving the first motor 20 with the engine 18. The first motor 20 is electrically connected to the battery 28, and the electricity generated by the first motor 20 is supplied to the battery 28 to charge it. The engine 18 is mechanically connected to the second motor 22 via the power split mechanism 24.

[0014] The second motor 22 is mechanically connected to the engine 18 via a power split mechanism 24. The second motor 22 is electrically connected to the battery 28 and operates by receiving power from the battery 28. The second motor 22 is mechanically connected to the front wheels 14 via a gear unit 26 and functions as a prime mover to drive 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. In addition to being a prime mover, the second motor 22 can also function as a generator for regenerative braking of the front wheels 14. That is, when the vehicle 10 needs to decelerate, it can perform regenerative braking of the front wheels 14 by making the second motor 22 function as a generator. The second motor 22 may also drive the rear wheels 16 as drive wheels instead of the front wheels 14.

[0015] The battery 28 is connected to the first motor 20 and the second motor 22. The battery 28 is a power supply for the second motor 22 and supplies driving power to the second motor 22. The battery 28 has a plurality of secondary battery cells and is configured to be repeatedly rechargeable and dischargeable. The secondary battery cells referred to here are not particularly limited, but may be lithium-ion battery cells or nickel-metal hydride battery cells, for example. Although not shown in the figures, power conversion devices may be provided between the battery 28 and the first motor 20, and between the battery 28 and the second motor 22, as needed.

[0016] The control device 30 is configured using a computer system and includes a processor, memory, etc. The control device 30 is electrically connected to the engine 18, battery 28, and gear unit 26, and is configured to control their operation. The control device 30 is also communicatively connected to the temperature sensor 32. The control device 30 receives input such as user operation information and vehicle information indicating the status of the vehicle. The operation information includes output information requested by the user to the engine 18, such as the amount of accelerator pedal operation and brake operation. The vehicle information includes information indicating the status of the engine 18, such as the temperature detected by the temperature sensor 32, and ON / OFF information of the vehicle 10's power switch (also called the ready switch or ignition switch).

[0017] The control device 30 cumulatively counts the number of times the vehicle 10 is started or stopped (also called ready-off) before the engine 18 has finished warming up, as the number of incomplete warm-ups. Here, "before the engine 18 has finished warming up" refers to, for example, when the temperature detected by the temperature sensor 32 is below a first predetermined temperature. The first predetermined temperature may be, for example, 80°C.

[0018] In addition, the control device 30 counts the number of incomplete warm-ups as a second incomplete warm-up when the temperature detected by the temperature sensor 32 is below the second predetermined temperature. The second predetermined temperature is lower than the first predetermined temperature and may be, for example, 50°C. That is, the second incomplete warm-up count refers to the number of times the vehicle 10 was started or stopped prematurely without the vehicle 10 warming up properly. The control device 30 controls the operation of each part of the vehicle 10 as described above, according to the input operation information, vehicle information, and the number of incomplete warm-ups.

[0019] Referring to Figures 2 and 3, a series of processes related to the warm-up of the engine 18 performed by the control device 30 will be described. The control device 30 is configured to perform the series of processes shown in Figure 2 when the vehicle 10 is started (also referred to as ready).

[0020] In step S12, the control device 30 reads the counted number of incomplete warm-up times.

[0021] In step S14, the control device 30 calculates a start threshold value from the number of incomplete warm-up times in step S12. The start threshold value is a threshold value for starting the engine 18 according to the required output for the engine 18. That is, the control device 30 starts the engine 18 when the required output for the engine 18 exceeds the start threshold value. As shown by the solid line A in FIG. 3, the control device 30 of the present embodiment changes the start threshold value set according to the number of incomplete warm-up times until the warm-up of the engine 18 is completed. Specifically, as the number of incomplete warm-up times increases, the start threshold value is set to a smaller value. That is, the engine 18 is more likely to be started with respect to the required output for the engine 18. On the other hand, the broken line B shown in FIG. 3 indicates the start threshold value in the normal control process. The start threshold value in the normal control process is constant regardless of the number of incomplete warm-up times.

[0022] In step S14, although the control device 30 sets the start threshold value according to the number of incomplete warm-up times, instead of or in addition to that, it may calculate a stop threshold value for stopping the engine 18. That is, the control device 30 stops the engine 18 when the required output for the engine 18 is below the stop threshold value. Therefore, if the stop threshold value is set to a larger value as the number of incomplete warm-up times increases, the engine 18 is less likely to be stopped with respect to the required output for the engine 18.

[0023] In step S16, the control device 30 reads the counted second number of incomplete warm-up times.

[0024] In step S18, the control device 30 determines whether the second number of incomplete warm-up times is equal to or greater than a predetermined value. If the second number of incomplete warm-up times is equal to or greater than the predetermined number (YES in S18), the control device 30 proceeds to the process of step S20. Otherwise (NO in S18), the control device 30 skips the process of step S20 and proceeds to the process of step S22.

[0025] In step S20, the control device 30 executes a warm-up acceleration control process. In the warm-up acceleration control process, the operating state of the engine 18 is controlled to accelerate the warm-up of the engine 18. For example, by performing control that reduces the fuel efficiency of the engine 18, such as increasing the rotational speed of the engine 18, the warm-up of the engine 18 is further accelerated.

[0026] In step S22, the control device 30 determines whether or not the engine 18 has finished warming up. The control device 30 determines that warming up is complete, for example, if the temperature detected by the temperature sensor 32 is above a first predetermined temperature (for example, 80°C). If warming up is complete (YES in step S22), the warm-up acceleration control process ends and the process proceeds to step S24. Otherwise (NO in step S22), the control device 30 continues the process in step S22 until warming up is complete.

[0027] Although not shown in the diagram, if the power switch is turned OFF (i.e., ready off) before the engine 18 has finished warming up, the control device 30 adds the count of the incomplete warm-up count and the second incomplete warm-up count, and terminates the series of processes, or returns to the process in step S12.

[0028] In step S24, the control device 30 performs normal control processing. As mentioned above, in normal control processing, a constant value is set for the starting threshold regardless of the number of incomplete warm-up cycles. That is, the control device 30 sets the starting threshold based on the dashed line B in Figure 3.

[0029] In step S26, the control device 30 determines whether the engine 18 has been warmed up for a predetermined time or longer. The control device 30 determines that the warm-up time has been for a predetermined time or longer if, for example, the temperature detected by the temperature sensor 32 is maintained at, for example, 80°C or higher for approximately 30 minutes. If the warm-up time has been for a predetermined time or longer (YES in S26), the control device 30 proceeds to the process in step S28. Otherwise (NO in S26), the control device 30 returns to the process in step S24 and continues the normal control process.

[0030] In step S28, the control device 30 subtracts or clears the number of incomplete warm-up cycles and the second number of incomplete warm-up cycles. For example, if the user's usage of the vehicle 10 (e.g., the user's main driving route) changes, it is possible to prevent the start threshold and / or stop threshold, which have been adjusted according to the previous usage, from becoming excessive for the new usage.

[0031] Based on the above, the control device 30 terminates or repeats the process of executing the series of steps S12-S28. As described above, the control device 30 can change the conditions related to starting / stopping the engine 18 (i.e., the starting threshold and / or stopping threshold) according to the number of times the engine has not been fully warmed up. For example, if the number of times the engine has not been fully warmed up is large, the control device 30 can adjust each threshold to lower the starting threshold for the engine 18 or raise the stopping threshold for the engine 18. This can increase the number of times the engine 18 is started and the starting time, thereby accelerating the warm-up of the engine.

[0032] The process of performing the series of steps S12-S28 described above is just one example. The control device 30 does not have to perform the processes in steps S16-S24, for example. In other words, the warm-up acceleration control process based on the second number of incomplete warm-up cycles is an optional additional process. [Explanation of symbols]

[0033] 10: Hybrid vehicle, 18: Engine, 30: Control device

Claims

[Claim 1] A control device for a hybrid vehicle, The process involves counting the number of times the hybrid vehicle was started or stopped before the engine warm-up was complete as the number of incomplete warm-ups. When the hybrid vehicle is started, a process is performed to set at least one of the starting threshold and stopping threshold for the engine according to the number of incomplete warm-ups, such that the starting threshold is made smaller or the stopping threshold is made larger as the number of incomplete warm-ups is increased. A process to start the engine when the request output for the engine exceeds the set start threshold, and to stop the engine when the request output falls below the set stop threshold, When the hybrid vehicle remains running and a predetermined time has elapsed since the engine warm-up was completed, the process of subtracting or clearing the counted number of incomplete warm-ups is performed. A control device capable of performing the following actions.

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