JP7091759B2 - Hybrid vehicle control device - Google Patents

Description

The present disclosure relates to a control device for a hybrid vehicle.

Conventionally, in a hybrid vehicle capable of motor assist in which the power of an engine is assisted by the power of a motor, a hybrid vehicle having an SCR (Selective Catalytic Reduction) catalyst in the exhaust passage of the engine is known (see, for example, Patent Document 1). Such an SCR catalyst adsorbs ammonia generated by hydrolysis of urea water injected into the exhaust gas from the urea water injection valve, and selectively reduces NOx in the exhaust gas using the adsorbed ammonia. (See, for example, Patent Documents 1 and 2). The ammonia adsorption capacity of the SCR catalyst tends to decrease as the temperature of the SCR catalyst increases (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2014-227072 Japanese Unexamined Patent Publication No. 2010-31731

As described above, the ammonia adsorption capacity of the SCR catalyst decreases as the temperature of the SCR catalyst increases, so the engine output value required for the engine of the hybrid vehicle increases, and the engine output actually increases accordingly to exhaust. When the temperature rises, the temperature of the SCR catalyst rises with the rise in the exhaust temperature, and there is a possibility that ammonia slip in which the ammonia adsorbed on the SCR catalyst is released from the SCR catalyst may occur.

The present disclosure has been made in view of the above, and an object thereof is to provide a control device for a hybrid vehicle capable of suppressing the occurrence of ammonia slip.

In order to achieve the above object, the control device for a hybrid vehicle according to an embodiment of the present invention is a control device applied to a hybrid vehicle capable of motor assist in which the power of an engine is assisted by the power of a motor, and the engine. Based on the temperature of the SCR catalyst arranged in the exhaust passage of the SCR catalyst and the amount of ammonia adsorbed by the SCR catalyst, the slip-free engine output value which is the upper limit of the engine output in which ammonia slip is not generated from the SCR catalyst. When the engine output required value, which is the engine output value required for the engine, is larger than the slip-free engine output value acquired by the acquisition unit, the engine output value is used as the engine output value. A control unit that executes a control process that sets the output value of the non- slip engine and increases the output value of the motor at the time of motor assist according to the difference between the required engine output value and the non-slip engine output value. The higher the temperature of the SCR catalyst, the lower the slip-free engine output value .

According to the above-mentioned hybrid vehicle control device, the occurrence of ammonia slip can be suppressed.

It is a schematic block diagram of the hybrid vehicle which concerns on embodiment. This is an example of a flowchart of the ammonia slip suppression control process executed by the control device according to the embodiment. It is the figure which visualized the map used when calculating the slip non-occurrence engine output value.

Hereinafter, the control device 30 of the hybrid vehicle 1 according to the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram schematically showing the configuration of the hybrid vehicle 1. The hybrid vehicle 1 includes an engine 2, an exhaust passage 3, a power transmission shaft 4a, 4b, 4c, a transmission 5, a motor clutch 6, a motor 7, an inverter 8, a battery 9, and an exhaust purification device 10. , Various sensors (temperature sensor 20 is exemplified in FIG. 1), and a control device 30.

In the present embodiment, as an example of the engine 2, a diesel engine using light oil as fuel is used. The fuel injection amount, fuel injection timing, and the like of the engine 2 are controlled by the control device 30. The exhaust passage 3 is a passage through which the exhaust (E) discharged from the engine 2 passes, and its upstream end is branched and connected to the exhaust port of each cylinder of the engine 2. The power transmission shaft 4a is a shaft for transmitting power between the engine 2 and the transmission 5. The power transmission shaft 4b is a shaft that transmits power between the transmission 5 and a differential gear (not shown) for drive wheels. The power transmission shaft 4c is a shaft that transmits power between the transmission 5 and the motor 7. As the transmission 5, an AT (Automatic Transmission) or an AMT (Automated Manual Transmission) that is controlled by the control device 30 to change the gear stage can be used.

The motor clutch 6 is arranged in a portion of the power transmission shaft 4c between the transmission 5 and the motor 7, and switches between a disconnected state and a connected state in response to an instruction from the control device 30. When the motor clutch 6 is in the disconnected state, power transmission between the motor 7 and the transmission 5 becomes impossible, and when the motor clutch 6 is in the connected state, the power transmission between the motor 7 and the transmission 5 becomes impossible. It will be possible. Although this will be described later, the control device 30 according to the present embodiment has a motor clutch 6 at the time of motor assist in which the power of the engine 2 is assisted by the power of the motor 7 and at the time of regenerative power generation in which the motor 7 performs regenerative power generation. To be connected.

The motor 7 is electrically connected to the battery 9 via the inverter 8. At the time of motor assist, the motor 7 assists the power of the engine 2 by receiving and driving the electric power supplied from the battery 9. Further, at the time of regenerative power generation, the motor 7 is driven by transmitting the power from the transmission 5 side (this is the power from the engine 2 or the power from the drive wheels) to generate the regenerative power generation. conduct. The electric power obtained by this regenerative power generation is charged in the battery 9. As such a motor 7, for example, a permanent magnet type AC synchronous motor or the like can be used. Further, as the battery 9, various batteries such as a lithium ion battery and a nickel hydrogen battery can be used.

The connection mode between the engine 2 and the motor 7 in the hybrid vehicle 1 may be at least a configuration capable of motor assist, and the specific configuration thereof is not limited to the above-mentioned configuration.

The exhaust gas purification device 10 is a device for purifying exhaust gas. Specifically, the exhaust gas purification device 10 according to the present embodiment includes an oxidation catalyst 11, a filter 12, an SCR catalyst 13, an ammonia slip catalyst 14, and a urea water injection valve 15. The oxidation catalyst 11, the filter 12, the SCR catalyst 13, and the ammonia slip catalyst 14 are arranged in the exhaust passage 3 in this order.

The filter 12 is a member having a function of collecting PM (Particulate Matter; particulate matter) contained in the exhaust gas. The oxidation catalyst 11 has a structure in which a noble metal catalyst such as platinum (Pt) or palladium (Pd) is supported on a carrier through which exhaust gas can pass. The oxidation catalyst 11 promotes an oxidation reaction that changes nitric oxide (NO) in the exhaust to nitric oxide (NO ₂ ) by the oxidation catalytic action of the noble metal catalyst. When the exhaust temperature becomes higher than a predetermined temperature, the PM collected in the filter 12 can be burned by the nitrogen dioxide generated in the oxidation catalyst 11 and discharged as carbon dioxide (CO ₂ ).

The SCR catalyst 13 is a catalyst that adsorbs ammonia (NH ₃ ) produced by hydrolysis of urea water and selectively reduces NOx in the exhaust by using the adsorbed ammonia. The specific type of this catalyst is not particularly limited, and known SCR catalysts such as vanadium, copper, iron and the like can be used. The ammonia slip catalyst 14 is an oxidation catalyst that oxidizes ammonia in the exhaust gas downstream of the SCR catalyst 13.

The urea water injection valve 15 is connected to the urea water storage tank (not shown) via a pipe (not shown). The urea water injection valve 15 is supplied with the urea water stored in the urea water storage tank. The urea water injection valve 15 injects urea water toward the exhaust gas in the exhaust passage 3 on the downstream side of the filter 12 and on the upstream side of the SCR catalyst 13 in response to the instruction of the control device 30. When urea water is supplied into the exhaust from the urea water injection valve 15, urea in the urea water is hydrolyzed, and as a result, ammonia is produced. This ammonia is adsorbed on the SCR catalyst 13 and reduces NOx under the catalytic action of the SCR catalyst 13. As a result, nitrogen (N ₂ ) and water (H ₂ O) are produced. In this way, NOx in the exhaust is reduced.

The exhaust gas purification device 10 may not be provided with the ammonia slip catalyst 14. However, when the exhaust gas purification device 10 is provided with the ammonia slip catalyst 14 as in the present embodiment, the ammonia in the exhaust gas is released into the atmosphere as compared with the case where the exhaust gas purification device 10 is provided with the ammonia slip catalyst 14. It is preferable in that it can be suppressed more effectively.

The temperature sensor 20 detects the temperature of the SCR catalyst 13 and conveys the detection result to the control device 30. In addition to the temperature sensor 20, the hybrid vehicle 1 has various sensors for detecting various information used for the operation of the hybrid vehicle 1 (for example, a vehicle speed sensor for detecting the vehicle speed and an accelerator opening for detecting the accelerator opening). It is equipped with a sensor, a brake opening sensor that detects the brake opening, etc.).

The control device 30 includes a microcomputer having a CPU (Central Processing Unit) 31 that executes various control processes, and a storage unit 32 that stores various data, programs, and the like used for the operation of the CPU 31. Specifically, the storage unit 32 includes a ROM (Read Only Memory) and a RAM (Random).
It is composed of a storage medium such as Access Memory).

The control device 30 according to the present embodiment normally disconnects the motor clutch 6. For example, when the hybrid vehicle 1 starts or accelerates, the control device 30 connects the motor clutch 6 and drives the motor 7 by supplying electric power from the battery 9, thereby supplying the power of the engine 2 to the motor 7. It is assisted by power (that is, motor assist is performed). Further, the control device 30 makes the motor 7 generate regenerative power generation by connecting the motor clutch 6 to the motor clutch 6 during inertial running or brake braking of the hybrid vehicle 1, and uses the electric power obtained by the regenerative power generation as a battery. Let 9 be charged.

Further, the control device 30 according to the present embodiment also executes a control process for suppressing ammonia slip (hereinafter, referred to as “ammonia slip suppression control process”). The details of this ammonia slip suppression control process will be described as follows using a flowchart.

FIG. 2 is an example of a flowchart of the ammonia slip suppression control process executed by the control device 30. Each step in the flowchart of FIG. 2 is executed by the CPU 31 of the control device 30 based on a program. Further, the control device 30 first starts the flowchart of FIG. 2 when the hybrid vehicle 1 is started (when the start switch is turned on).

In step S10, the control device 30 acquires the temperature of the SCR catalyst 13 (referred to as the SCR catalyst temperature) and the adsorption amount of ammonia adsorbed on the SCR catalyst 13 (referred to as the ammonia adsorption amount). Specifically, the control device 30 according to the present embodiment acquires the SCR catalyst temperature based on the detection result of the temperature sensor 20. Further, the control device 30 acquires the ammonia adsorption amount of the SCR catalyst 13 based on the output (fuel injection amount) of the engine 2 and the supply amount of urea water from the urea water injection valve 15 (for example, JP-A-2014-2014). See 227889). More specifically, the storage unit 32 of the control device 30 stores in advance a map and a calculation formula for calculating the amount of ammonia adsorbed based on the output of the engine 2 and the supply amount of urea water, and controls the control. The apparatus 30 calculates the amount of ammonia adsorbed using this map and the calculation formula, and uses this calculated value as the amount of ammonia adsorbed in step S10.

The specific execution method of step S10 is not limited to the above contents, and other known techniques can also be used. For example, when the control device 30 acquires the temperature of the SCR catalyst 13, the temperature of the SCR catalyst 13 is estimated by estimating the temperature of the SCR catalyst 13 based on a parameter having a correlation with the temperature of the SCR catalyst 13. You can also get it. Further, the control device 30 calculates the NOx purification rate of the SCR catalyst 13 based on the deviation of the NOx amount between the inlet and the outlet of the SCR catalyst 13 in acquiring the ammonia adsorption amount, and uses the calculated NOx purification rate as the calculated NOx purification rate. This can also be obtained by calculating the amount of ammonia adsorbed based on this (see, for example, Patent Document 1).

Next, in step S20, the control device 30 acquires the “slip-free engine output value (A1)”, which is the upper limit of the engine output in which the “ammonia slip” in which ammonia is released from the SCR catalyst 13 does not occur. Specifically, the control device 30 according to the present embodiment acquires the slip-free engine output value (A1) with reference to the map described below.

FIG. 3 is a diagram that visualizes the map used when calculating the slip-free engine output value. The horizontal axis of FIG. 3 shows the SCR catalyst temperature, and the vertical axis shows the amount of ammonia adsorbed by the SCR catalyst 13. On the horizontal axis of FIG. 3, the SCR catalyst temperature increases toward the right side, and the amount of ammonia adsorbed increases toward the upper side on the vertical axis. Each numerical value (an to h _n ) in the map of FIG. 3 represents a slip- _free engine output value. Specifically, each numerical value (an to h _n ) in this map _is an upper limit of the fuel injection amount in which ammonia slip does not occur. As described above, the map of FIG. 3 is a map in which the slip-free engine output value is defined in relation to the SCR catalyst temperature and the amount of ammonia adsorbed.

This map is obtained by conducting experiments, simulations, and the like in advance, and is stored in advance in the storage unit 32 (for example, ROM). In this map, the higher the SCR catalyst temperature, the lower the slip-free engine output value. The control device 30 extracts the slip-free engine output value corresponding to the SCR catalyst temperature and the ammonia adsorption amount acquired in step S10 from this map, and uses this extracted value as the slip-free engine output according to step S20. Obtained as a value (A1). By acquiring the non-slip engine output value based on the map in this way, the non-slip engine output value can be easily acquired by a simple method.

With reference to FIG. 2 again, after step S20, the control device 30 determines the “engine output required value (A2)” which is the output value (engine output value) of the engine power required for the engine 2 in step S30. get. Specifically, in the present embodiment, as an example of this engine output required value, the fuel injection amount required for the engine 2 is acquired. More specifically, the control device 30 calculates the fuel injection amount required for the engine 2 based on the accelerator opening degree (which is an index corresponding to the depression amount of the accelerator pedal), and the calculated fuel. The injection amount is acquired as "engine output required value (A2)".

Next, in step S40, the control device 30 determines whether or not the engine output request value (A2) acquired in step S30 is larger than the slip-free engine output value (A1) acquired in step S20. When NO is determined in step S40 (when A2 ≦ A1), the control device 30 re-executes the flowchart from the start (return).

On the other hand, if YES is determined in step S40 (when A2> A1), the control device 30 executes step S50. Here, in the case where YES is determined in step S40, if the engine 2 actually outputs the engine output corresponding to the engine output request value (A2), ammonia slip will occur. Therefore, in step S50, the control device 30 sets the output value of the motor 7 (the value of the power output by the motor 7) at the time of motor assist to the engine output request value (A2) and the slip-free engine output value (A1). A control process (hereinafter, referred to as “motor output increase control process”) for increasing according to the difference (“A2-A1”) from the above is executed. The specific contents of this step S50 are as follows.

First, if the hybrid vehicle 1 is not motor-assisted running before the execution of step S50 (specifically, if the hybrid vehicle 1 is running alone with only the power of the engine 2), In step S50, the control device 30 switches the traveling mode of the hybrid vehicle 1 to the motor assist traveling by starting the motor assist that assists the power of the engine 2 by the power of the motor 7. Then, the control device 30 increases the output value of the motor 7 at the time of this motor assist as the value of "A2-A1" becomes larger.

Specifically, in this step S50, the control device 30 controls the output value of the motor 7 at the time of motor assist so that the power of the engine 2 corresponding to "A2-A1" is supplemented by the power of the motor 7. More specifically, the control device 30 calculates the power of the engine 2 (that is, the engine torque (Nm)) obtained by the fuel injection amount of "A2-A1", and this calculated power (this is The power of the motor 7 assists the power of the engine 2 so that the power of the motor 7 (that is, the motor torque (Nm)) compensates for the shortage of the engine torque). As a result of the motor assist being performed in this way, the output value of the motor 7 at the time of motor assist increases as the value of "A2-A1" increases.

Even when the driving mode of the hybrid vehicle 1 is already motor-assisted driving before the execution of step S50, the control device 30 sets the output value of the motor 7 at the time of motor assist as described above. It is increased according to the value of "A2-A1". Specifically, the control device 30 controls the output value of the motor 7 at the time of motor assist so that the power of the engine 2 corresponding to "A2-A1" is supplemented by the power of the motor 7.

By executing the motor output increase control process according to step S50, it is possible to suppress an increase in the actual output value of the engine 2, so that an increase in the exhaust temperature can be suppressed. As a result, it is possible to suppress an increase in the SCR catalyst temperature and suppress the occurrence of ammonia slip.

After step S50, the control device 30 re-executes the flowchart from the start (return). The time to end the execution of the motor output increase control process according to step S50 is not particularly limited, but for example, in the control device 30, the flowchart is executed again from the start after step S50 is executed once. In this case, if NO is determined in step S40 (in the case of A2 ≦ A1), the execution of this motor output increase control process may be terminated. That is, in this case, the motor output increase control process is continuously executed until A1 ≧ A2. Alternatively, the control device 30 may end the execution of the motor power ratio increase control process after a predetermined time has elapsed from the start of the execution of the motor output increase control process according to step S50. It should be noted that an appropriate value may be obtained in advance for this predetermined time and stored in the storage unit 32.

The CPU 31 of the control device 30 that executes steps S10 to S30 serves as an "acquisition unit" for acquiring various information (SCR catalyst temperature, ammonia adsorption amount, slip-free engine output value, engine output required value). This is an example of a member having a function. Further, the CPU 31 of the control device 30 that executes step S40 is an example of a member having a function as a "determining unit" for determining whether or not the engine output required value is larger than the slip-free engine output value. Then, when the engine output required value is larger than the slip-non-occurring engine output value, the CPU 31 of the control device 30 that executes step S50 sets the output value of the motor 7 at the time of motor assist to the engine output required value and the slip. This is an example of a member having a function as a "control unit" that executes a control process that increases according to a difference from the non-generated engine output value.

According to the present embodiment as described above, when the engine output required value (A2) is larger than the slip-free engine output value (A1) (YES in step S40), the motor output increased according to step S50. Since the control process is executed, it is possible to suppress an increase in the exhaust temperature and suppress an increase in the SCR catalyst temperature. This makes it possible to suppress the occurrence of ammonia slip.

Specifically, according to the present embodiment, when the required engine output value (A2) is larger than the non-slip engine output value (A1), the power of the engine 2 is increased by the motor output increase control process according to step S50. Since it is possible to suppress the occurrence of ammonia slip while compensating for the shortage with the power of the motor 7, it is possible to suppress the occurrence of ammonia slip while suppressing the deterioration of the drivability of the hybrid vehicle 1.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to such a specific embodiment, and various modifications and modifications are made within the scope of the gist of the present invention described in the claims. Is possible.

1 Hybrid vehicle 2 Engine 3 Exhaust passage 7 Motor 10 Exhaust purification device 13 SCR catalyst 20 Temperature sensor 30 Control device 31 CPU (acquisition unit, control unit)
32 Memory

Claims (2)

It is a control device applied to hybrid vehicles that can assist motors by assisting the power of the engine with the power of the motor.
A non-slip engine, which is the upper limit of the engine output in which ammonia is released from the SCR catalyst based on the temperature of the SCR catalyst arranged in the exhaust passage of the engine and the amount of ammonia adsorbed by the SCR catalyst. The acquisition unit that acquires the output value and
When the engine output required value, which is the engine output value required for the engine, is larger than the non-slip engine output value acquired by the acquisition unit, the engine output value is changed to the non-slip engine output value. In addition, a control unit that executes a control process for increasing the output value of the motor at the time of motor assist according to the difference between the engine output required value and the slip-free engine output value is provided .
A control device for a hybrid vehicle, characterized in that the higher the temperature of the SCR catalyst, the lower the slip-free engine output value . It is provided with a storage unit that stores in advance a map in which the slip-free engine output value is associated with the temperature of the SCR catalyst and the amount of ammonia adsorbed by the SCR catalyst.
The acquisition unit acquires the temperature of the SCR catalyst and the amount of ammonia adsorbed by the SCR catalyst, and obtains the slip-free engine output value corresponding to the acquired temperature of the SCR catalyst and the amount of ammonia adsorbed by the SCR catalyst. The control device for a hybrid vehicle according to claim 1, wherein the non-slip engine output value is acquired by extracting from the map.

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