JP2018189048A - Motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device capable of suppressing erosion and damage of a filter.SOLUTION: A motor control device according to an embodiment which is applicable to a vehicle equipped with a filter for collecting particulate matter in exhaust gas from an internal combustion engine and a motor generating driving force to be transmitted to the internal combustion engine includes a regeneration control section for controlling regeneration of the filter, and a motoring control section for rotating the internal combustion engine with the driving force of the motor when an idle drop state is determined during regeneration of the filter.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a motor control device that rotates an internal combustion engine by a driving force of an on-vehicle electric motor.

  Since exhaust gas from the internal combustion engine of the vehicle contains PM (that is, particulate matter), a filter is provided in the exhaust system.

  When the internal combustion engine is a diesel engine, the filter is called a DPF (Diesel Particulate Filter) or the like. When the internal combustion engine is a gasoline engine, the filter is called a GPF (Gasoline Particulate Filter) or the like.

  In order to prevent deterioration of the function of the filter, when a predetermined amount of PM accumulates in the filter, it is burned. Such PM combustion processing is sometimes called filter regeneration.

JP 2011-153591 A

  During the filter regeneration, the internal combustion engine may shift from normal operation to low rotation / low load operation. Such a state is known as an idle drop (Drop to Idle). When such an idle drop occurs, the amount of heat taken away from the filter by the exhaust gas decreases, so that the temperature of the filter rapidly increases. As a result, the filter may be damaged due to melting or cracking.

  Therefore, an object of the present disclosure is to provide a motor control device capable of suppressing melting damage and breakage of a filter.

  One form of the present disclosure is a motor control device applicable to a vehicle including a filter that collects particulate matter in exhaust gas from an internal combustion engine and an electric motor that generates a driving force to be transmitted to the internal combustion engine. A regeneration control unit that controls regeneration of the filter, and a motoring control unit that rotates the internal combustion engine with the driving force of the electric motor when it is determined that an idle drop state has occurred during regeneration of the filter. It is directed to the motor control device provided.

  According to an embodiment of the present disclosure, it is possible to provide a motor control device that can suppress melting and breakage of a filter.

Schematic diagram showing the overall configuration of a hybrid vehicle including the motor control device of the present disclosure The flowchart which shows the process of the motor control apparatus of FIG.

  Hereinafter, the motor control device 121 according to an embodiment of the present disclosure will be described in detail with reference to the drawings.

<1. Definition>
Table 1 below shows the meanings of acronyms and abbreviations used in the present embodiment.

<2. Embodiment>
<2-1. Overall configuration of HEV1>
In FIG. 1, a hybrid electric vehicle (hereinafter referred to as HEV) 1 generally includes an internal combustion engine 11 and an M / G 13, and both the internal combustion engine 11 and the M / G 13 are used as a power source for driving wheels 15. Is done. This type of HEV1 is sometimes called a parallel hybrid.

  HEV1 further includes a first clutch 17, a second clutch 19, a transmission 111, an exhaust passage 113, a filter 115, an inverter 117, a battery 119, an ECM 121, and the like.

  The internal combustion engine 11 is, for example, a diesel engine or a gasoline engine. In the present disclosure, the description will be continued assuming that the internal combustion engine 11 is a diesel engine.

  The first clutch 17 is interposed between the internal combustion engine 11 and the M / G 13. The first clutch 17 is controlled to one of a complete contact state, a complete disconnection state, and a slip state by a control signal CS1 for the first clutch from the ECM 121, for example.

  For example, the M / G 13 may be a synchronous motor generator in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator. The M / G 13 is supplied with the three-phase AC power generated by the inverter 117 in accordance with the control signal CS2 from the ECM 121. In this case, the M / G 13 functions as an electric motor that rotates upon receiving supply of three-phase AC power.

  Further, for example, when receiving rotational energy from the internal combustion engine 11, the M / G 13 can also function as a generator that generates electromotive force at both ends of the stator coil.

  The second clutch 19 is interposed between the M / G 13 and the transmission 111. The second clutch 19 is controlled to one of a complete contact state, a complete disconnection state, and a slip state by a control signal CS3 for the second clutch from the ECM 121, for example.

  The transmission 111 is a stepped transmission having a plurality of shift stages established by selectively engaging a plurality of friction engagement elements. The transmission 111 performs upshift or downshift by engaging or releasing the friction engagement element in response to a transmission control signal CS4 generated by the ECM 121 or the like based on the accelerator opening (described above) or the vehicle speed. Perform a shift.

  The exhaust passage 113 guides the exhaust gas generated by the operation of the internal combustion engine 11 to the downstream side.

  The filter 115 is provided in the middle of the exhaust passage 113 and includes, for example, a ceramic wall flow type carrier. In this carrier, a catalyst may be supported or coated on the cell partition wall. When exhaust gas is introduced into such a filter 115, PM accumulates on the cell partition walls, thereby collecting PM in the exhaust gas.

  The filter 115 may be called DPF when the internal combustion engine 11 is a diesel engine, and may be called GPF when the internal combustion engine 11 is a gasoline engine (more specifically, a direct injection engine).

  If the internal combustion engine 11 is a diesel engine, an exhaust purification catalyst such as SCR may be provided in the exhaust passage 113 as another aftertreatment device. If the internal combustion engine 11 is a gasoline engine, a three-way catalyst may be provided in the exhaust passage 113 as another aftertreatment device. Since these other post-processing apparatuses are not the main part of the present disclosure, explanation thereof will be omitted.

  Water, nitrogen, carbon dioxide and the like produced by treating exhaust gas with various post-treatment devices are discharged into the atmosphere via a muffler (not shown).

  The ECM 121 is a motor control device 121 according to the present disclosure, and includes, for example, a microcomputer, a nonvolatile memory, a working memory, and the like mounted on a substrate. The microcomputer executes a program stored in advance in a nonvolatile memory or the like using the working memory, and functions as the reproduction control unit 123 and the motoring control unit 125 in the present disclosure.

<2-2. Processing of Motor Control Device 121>
Next, the process of the motor control device 121 will be described with reference to FIG.

  In FIG. 2, the ECM 121 determines whether or not it is time to perform regeneration of the filter 115 (step S001).

  As a determination method in step S001, a known technique can be applied. For example, the following is exemplified.

  First, the soot generation amount of the internal combustion engine 11 is estimated by the ECM 121 or the like by a so-called soot generation model. Based on this soot discharge amount, the PM accumulation amount in the filter 115 is estimated by the ECM 121 or the like. In step S001, the ECM 121 determines YES if the estimated PM deposition amount is equal to or greater than a reference value obtained in advance through experiments or the like, and otherwise determines NO.

  Second, a known PM sensor may be provided on the upstream side of the filter 115 in the exhaust passage 113. Based on the detection value of the PM sensor, the PM accumulation amount in the filter 115 is estimated by the ECM 121 or the like. In step S001, the ECM 121 determines YES if the estimated PM accumulation amount is equal to or greater than the reference value, and otherwise determines NO.

  If it is determined NO in step S001, the ECM 121 ends the process of FIG.

  On the other hand, if it is determined YES in step S001, the ECM 121 functions as the regeneration control unit 123 and starts regeneration of the filter 115 (step S003).

  A publicly known technique can be applied as the filter regeneration method in step S003, and the following is exemplified.

  First, when the filter 115 is equipped with a heater, the ECM 121 energizes the heater to burn the PM accumulated in the filter 115.

  Second, the ECM 121 burns PM accumulated in the filter 115 by post injection (additional injection after the combustion process), exhaust pipe injection, or the like.

  After step S003, the ECM 121 determines whether or not the internal combustion engine 11 is in an idle drop state (step S005).

  In step S005, for example, in the present disclosure, if the HEV 1 stops from the normal travel (that is, if the vehicle speed becomes zero), it is determined that the idle drop state is set, and YES is determined. On the other hand, if HEV1 does not stop from the normal running, it is determined as NO.

  Here, the normal operation of the internal combustion engine 11 will be described. During normal travel of HEV1, the internal combustion engine 11 is used as a main power source. At this time, both clutches 17 and 19 are brought into a fully engaged state by the control signals CS1 and CS3 from the ECM 121. Further, the internal combustion engine 11 generates power by repeating the following steps under the control of the ECM 121 and the like.

  In the internal combustion engine 11, when the intake valve opens and the piston descends, gas is sucked into the cylinder. When the piston reaches bottom dead center, the intake valve is closed (intake process).

  As the piston rises from the bottom dead center, the gas in the cylinder is compressed (compression stroke).

  When the piston reaches near the top dead center, the fuel in the cylinder is supplied and burned. Combustion gas expands and lowers the piston (combustion process).

  When the piston reaches bottom dead center, the exhaust valve is opened, and the combustion gas is sent as exhaust gas to the exhaust passage 113 (exhaust process).

  The power generated by the internal combustion engine 11 through the above steps is transmitted in the order of the first clutch 17, the M / G 13, the second clutch 19, the transmission 111, and the like, and finally rotates the wheels 15.

  Further, the exhaust gas sent to the exhaust passage 113 is guided to the filter 115 through the exhaust passage 113. The filter 115 is being regenerated, but collects PM in the exhaust gas as described above. During this time, the heat quantity of the filter 115 is taken away downstream of the exhaust passage 113 by the exhaust gas passing through the filter 115.

  However, as described above, when the HEV 1 that has been traveling normally stops during regeneration of the filter 115, the rotational speed of the internal combustion engine 11 decreases to the idle rotational speed. Moreover, if HEV1 is an idling stop vehicle, the number of revolutions is zero. That is, the internal combustion engine 11 shifts from normal operation to low rotation and low load operation. As a result, the amount of heat taken away by the exhaust gas is drastically reduced. Such a sudden decrease in the amount of heat taken away causes melting and breakage of the filter 115 as described in the section “Problems to be Solved by the Invention”.

  Therefore, in the present disclosure, when YES is determined in step S005, the ECM 121 functions as the motoring control unit 125 and starts motoring of the internal combustion engine 11 (step S007). In other words, the M / G 13 generates a driving force by the electric power stored in the battery 119 under the control of the ECM 121, and the internal combustion engine 11 is rotated by the driving force from the M / G 13.

  Hereinafter, step S007 will be described in more detail.

  By the control signals CS1 and CS3 from the ECM 121, the first clutch 17 is brought into a fully engaged state, while the second clutch 19 is brought into a completely disconnected state.

  Further, the inverter 117 generates three-phase AC power from the DC power supplied from the battery 119 under the control of the ECM 121 and the like, and supplies it to the M / G 13. The M / G 13 functions as an electric motor and is rotated by the supplied three-phase AC power. This rotational force is transmitted to the internal combustion engine 11 via the first clutch 17 and rotationally drives the crankshaft of the internal combustion engine 11. Here, the rotational speed of the internal combustion engine 11 is appropriately designed as appropriate. For example, it may be about the rotational speed during normal operation.

  The internal combustion engine 11 operates in the same manner as the above-described intake process to exhaust process by rotation of the crankshaft. However, since the amount of fuel supplied is small or zero, the exhaust gas sent from the exhaust valve to the exhaust passage 113 during step S007 is much lower than the temperature during normal operation.

  The exhaust gas sent to the exhaust passage 113 passes through the filter 115. During this time, the heat amount of the filter 115 is taken away downstream of the exhaust passage 113 by the low temperature exhaust gas passing through the filter 115. As described above, overheating of the filter 115 is prevented, and as a result, the filter 115 can be prevented from being melted or damaged.

  After step S007, the ECM 121 determines whether or not to end motoring (step S009).

  In step S009, for example, if the HEV 1 resumes normal travel or the regeneration of the filter 115 ends, it is determined YES. On the other hand, if neither the restart of normal running nor the end of regeneration is made, it is determined as NO.

  If NO is determined in step S009, the process returns to step S009 again.

  On the other hand, if YES is determined in the step S009, the ECM 121 performs a motoring end process (step S011).

  Hereinafter, an example of step S009 will be described in more detail. In order to suppress fuel consumption at the time of start, the ECM 121 transmits a control signal CS1 to bring the first clutch 17 into a complete disengagement state and transmits a control signal CS3 to bring the second clutch 19 into a complete engagement state.

  Further, the inverter 117 generates three-phase AC power as described above and supplies it to the M / G 13. The M / G 13 functions as an electric motor and is rotated by the supplied three-phase AC power. This rotational force is transmitted in the order of the second clutch 19 and the transmission 111 and the like, and finally the wheel 15 is rotationally driven.

  If it is determined to be NO after step S011 or at step S005, the ECM 121 determines whether or not to finish the regeneration of the filter 115 (step S013).

  As the processing in step S013, a known technique can be applied. For example, if it is determined that a predetermined time has elapsed since the start of step S003, YES can be determined in step S013.

  If “NO” is determined in the step S013, the process returns to the step S001, and if not, the process of FIG. 2 ends.

<2-3. Action and Effect of Motor Control Device 121>
As described above, when the HEV 1 stops traveling during regeneration of the filter 115, the motor control device 121 regards the internal combustion engine 11 to be in an idle drop state, and controls the internal combustion engine 11 to M / G 13 (motor) by motoring control. To forcibly rotate. As a result, when low-temperature exhaust gas passes through the filter 115, the amount of heat of the filter 115 is taken downstream of the exhaust passage 113. As described above, overheating of the filter 115 is prevented, and as a result, the filter 115 can be prevented from being melted or damaged.

<2-4. Addendum>
In the above description, in step S005, if HEV1 stops from normal driving (that is, if the vehicle speed becomes zero), it is determined as YES because it is in an idle drop state, otherwise it is determined as NO. .

  However, the present invention is not limited to this. In step S005, YES may be determined if the internal combustion engine 11 shifts from normal operation to low rotation / low load operation, and NO may be determined otherwise. That is, the vehicle speed is not necessarily zero and may be a low speed other than zero.

  In the above description, HEV 1 has been described as a parallel hybrid. However, the present invention is not limited to this, and the motor control device 121 can also be applied to the split-type HEV 1.

  The motor control device of the present disclosure can suppress the filter from being damaged or broken, and is suitable for a hybrid vehicle or the like.

1 HEV (vehicle)
11 Internal combustion engine 13 M / G (motor)
115 Filter 121 Motor Control Device 123 Reproduction Control Unit 125 Motoring Control Unit

Claims (2)

A motor control device applicable to a vehicle including a filter that collects particulate matter in exhaust gas from an internal combustion engine and an electric motor that generates a driving force to be transmitted to the internal combustion engine,
A regeneration control unit for controlling regeneration of the filter;
When it is determined that an idle drop state has occurred during regeneration of the filter, a motoring control unit that rotates the internal combustion engine with the driving force of the electric motor;
A motor control device comprising: When the motoring control unit rotates the internal combustion engine with the driving force of the electric motor, exhaust gas from the internal combustion engine passes through the filter to prevent overheating of the filter.
The motor control device according to claim 1.

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