Vehicle control device

Abstract

To provide a vehicle control device which can appropriately treat exhaust gas in starting an engine.SOLUTION: An HCU stores, in a RAM, brake information indicating an operation state of brakes in a period of an engine stopping (S1); when an engine start condition is satisfied (S4), adjusts fuel injection amount at starting the engine according to the brake information stored in the RAM (S5); and starts the engine 2 (S6).SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Conventionally, Patent Document 1 proposes a technology in which a canister purge process is carried out in which purge gas containing fuel vapor is released from the canister of a fuel evaporative emission control device into the intake passage during motoring, in which the internal combustion engine is rotated and driven by an electric motor without burning fuel in the internal combustion engine, thereby causing an oxidation reaction in the catalyst to reduce the amount of oxygen in the catalyst and suppressing the increase in emissions of NOx contained in the exhaust gas when the internal combustion engine is started. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-64741 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because the concentration of purge gas varies greatly, the conventional techniques described above have the problem that they may not be able to properly treat the exhaust gas when an internal combustion engine (hereinafter referred to as the "engine") is started.

[0005] The present invention has been made to solve the above-mentioned problems, and has an object to provide a vehicle control device that can appropriately treat exhaust gas when the engine is started. [Means for solving the problem]

[0006] The vehicle control device of the present invention is installed on a vehicle having an engine, a motor linked to the engine, a braking device, and a brake booster that enhances the braking force of the braking device by the intake negative pressure of the engine, and is equipped with a control unit that, when the negative pressure in the negative pressure chamber of the brake booster becomes lower than a predetermined negative pressure, drives the motor to rotate the engine and restore the negative pressure in the negative pressure chamber, and is equipped with a brake information storage unit that stores brake information representing the operating state of the braking device during a period when the engine is stopped, and the control unit is configured to adjust the fuel injection amount of the engine in accordance with the brake information stored in the brake information storage unit when the engine is started. Effect of the Invention

[0007] The present invention can provide a vehicle control device that can appropriately treat exhaust gas when the engine is started. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a vehicle equipped with a vehicle control device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a graph showing an example of a time series relationship between the operation state of the brake pedal, the brake negative pressure, the motoring execution state, and the amount of oxygen filling the catalytic converter in a vehicle equipped with a vehicle control device according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a graph showing examples of brake pedal operation states in a time series in a vehicle equipped with a vehicle control device according to an embodiment of the present invention, and FIGS. 3(a) to 3(d) show first to fourth examples of the brake pedal operation states, respectively. [Figure 4] FIG. 4 is a flowchart showing an operation at engine stop of the vehicle control device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A vehicle control device according to one embodiment of the present invention is provided for a vehicle having an engine, a motor interlocked with the engine, a brake device, and a brake booster that uses the intake negative pressure of the engine to increase the braking force of the brake device, and includes a control unit that drives the motor to rotate the engine and restore the negative pressure in the negative pressure chamber when the negative pressure in the negative pressure chamber of the brake booster falls below a predetermined negative pressure, and includes a brake information storage unit that stores brake information indicating the operating state of the brake device while the engine is stopped, and the control unit adjusts the amount of fuel injection into the engine according to the brake information stored in the brake information storage unit when the engine is started. This allows the vehicle control device according to the embodiment of the present invention to appropriately treat exhaust gas when the engine is started. EXAMPLES

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle equipped with a vehicle control device according to an embodiment of the present invention will now be described with reference to the drawings.

[0011] As shown in FIG. 1, the vehicle 1 includes an engine 2, a battery 3, a first motor 4 (hereinafter also referred to as "MG1"), a first inverter 5, a second motor 6 (hereinafter also referred to as "MG2"), a second inverter 7, a boost converter 8, driving wheels 9, a catalytic converter 10, a braking device 11, a brake booster 12, and a hybrid controller (hereinafter simply referred to as "HCU") 13.

[0012] A plurality of cylinders are formed in the engine 2. In this embodiment, the engine 2 generates power by performing a series of four strokes, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, for each cylinder.

[0013] The battery 3 is configured by a rechargeable secondary battery. The battery 3 accumulates the electric power generated by the MG1 and MG2, and supplies the electric power for driving the MG1 and MG2.

[0014] The MG1 is provided to operate in conjunction with the crankshaft of the engine 2. The MG1 is connected to the battery 3 via a first inverter 5 and a boost converter 8. The MG1 has a function as an electric motor that rotates when power is supplied from the battery 3 to rotate the crankshaft of the engine 2, and a function as a generator that converts the power generated by the engine 2 into electric power.

[0015] The MG2 is provided so as to move in conjunction with drive wheels 9 via a power transmission member such as a gear mechanism. The MG2 is connected to the battery 3 via a second inverter 7 and a boost converter 8.

[0016] The MG2 has a function of an electric motor that rotates the drive wheels 9 by being rotated when supplied with electric power from the battery 3 and the MG1, and a function of a generator that converts the rotational force of the drive wheels 9 into electric power.

[0017] The boost converter 8 is provided between the battery 3 and the first inverter 5 and second inverter 7, and boosts the voltage of the power supplied from the battery 3 to the first inverter 5 and second inverter 7, and lowers the voltage of the power supplied from the first inverter 5 and second inverter 7 to the battery 3.

[0018] The catalytic device 10 is provided in an exhaust passage of the engine 2. The catalytic device 10 has a three-way catalyst that removes harmful substances such as unburned hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) contained in the exhaust gas. The three-way catalyst oxidizes HC to water and carbon dioxide, oxidizes CO to carbon dioxide, and reduces NOx to nitrogen.

[0019] The braking device 11 applies a braking force to wheels such as the driving wheels 9 in response to an operating force applied to a brake pedal 16. The braking device 11 includes a brake 11a and a hydraulic circuit 11b that operates the brake 11a. The brake 11a in this embodiment is formed of a disc brake.

[0020] The brake booster 12 boosts the operating force of the brake pedal 16. The operating force of the brake pedal 16 boosted by the brake booster 12 is further boosted by the hydraulic circuit 11b and transmitted to the brake 11a.

[0021] The brake booster 12 is formed with a negative pressure chamber 12a for storing negative pressure and an atmospheric pressure chamber 12b to which atmospheric pressure is applied. The brake booster 12 boosts the operating force applied to the brake pedal 16 by the pressure difference between the pressure in the negative pressure chamber 12a and the pressure in the atmospheric pressure chamber 12b.

[0022] The negative pressure chamber 12a communicates with the intake passage of the engine 2 via a check valve 17. The check valve 17 is provided to prevent air from flowing from the intake passage of the engine 2 to the negative pressure chamber 12a and to allow air to flow from the negative pressure chamber 12a to the intake passage of the engine 2.

[0023] The negative pressure chamber 12a and the atmospheric pressure chamber 12b are disconnected when the brake pedal 16 is operated (hereinafter also simply referred to as the "operated state"), and are connected when the brake pedal 16 is not operated (hereinafter also simply referred to as the "non-operated state").

[0024] The atmospheric pressure chamber 12b is in a state in which it can take in atmospheric air when the brake pedal 16 is in an operated state, and is in a state in which it cannot take in atmospheric air when the brake pedal 16 is in a non-operated state.

[0025] When the brake pedal 16 changes from a non-operated state to an operated state, the volume of the atmospheric pressure chamber 12b increases and the volume of the negative pressure chamber 12a decreases. Therefore, when the brake pedal 16 changes from a non-operated state to an operated state, the negative pressure in the negative pressure chamber 12a decreases. In the present invention, a decrease in negative pressure means an increase in pressure, and conversely, an increase in negative pressure means a decrease in pressure.

[0026] When the brake pedal 16 is changed from an operated state to a non-operated state, the negative pressure chamber 12a and the atmospheric pressure chamber 12b communicate with each other, and the air in the atmospheric pressure chamber 12b flows into the negative pressure chamber 12a. As a result, the volumes of the atmospheric pressure chamber 12b and the negative pressure chamber 12a return to the original volumes when the brake pedal 16 was in the non-operated state, but the negative pressure in the negative pressure chamber 12a decreases.

[0027] The negative pressure in the negative pressure chamber 12a that has decreased when the brake pedal 16 changes from a non-operated state to an operated state, and the negative pressure in the negative pressure chamber 12a that has decreased when the brake pedal 16 changes from an operated state to a non-operated state, are restored by the intake negative pressure of the engine 2.

[0028] The HCU13 is composed of a computer unit equipped with a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, etc., an input port, and an output port.

[0029] The ROM of this computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the HCU 13. That is, the CPU executes the program stored in the ROM using the RAM as a working area, causing the computer unit to function as the HCU 13 in this embodiment.

[0030] An input port of the HCU 13 is connected to various sensors including a brake switch 21 that detects whether the brake pedal 16 is operated. An output port of the HCU 13 is connected to various control objects including a first inverter 5, a second inverter 7, a boost converter 8, an injector 31 that supplies fuel to the engine 2, and an ignition plug 32 that ignites in the combustion chamber of the engine 2. When the engine 2 is configured with an engine that does not require an ignition plug, such as a diesel engine, the ignition plug 32 is excluded from the configuration of the vehicle 1.

[0031] The HCU 13 controls various control objects connected to the output port based on information obtained from various sensors connected to the input port. In this embodiment, the HCU 13 has a function as a control unit 40 that, when the negative pressure in the negative pressure chamber 12a (hereinafter also simply referred to as "brake negative pressure") becomes lower than a predetermined negative pressure, controls the first inverter 5 to drive the MG1 to rotate the crankshaft of the engine 2 and executes motoring to restore the brake negative pressure.

[0032] The RAM of the HCU 13 has a storage area constituting a brake information accumulation unit 41 that accumulates brake information representing the operating state of the brake device 11 while the engine 2 is stopped. In this embodiment, the brake information represents the operation state of the brake pedal 16 in chronological order.

[0033] FIG. 2 is a graph showing an example of the relationship between the operation state of the brake pedal 16, the brake negative pressure, the motoring execution state, and the amount of oxygen filling the catalytic converter 10 (hereinafter simply referred to as the "oxygen filling amount") over time.

[0034] At time t0, the supply of fuel to the engine 2 is stopped, and the engine 2 is stopped. At time t1, the brake pedal 16 changes from a non-operated state (hereinafter also simply referred to as "OFF") to an operated state (hereinafter also simply referred to as "ON"), and the brake negative pressure decreases.

[0035] At time t2, when the brake pedal 16 is changed from ON to OFF, the brake negative pressure is further reduced. At time t3, when the brake pedal 16 is changed from OFF to ON, the brake negative pressure is further reduced.

[0036] At time t4, when the brake pedal 16 changes from ON to OFF, the brake negative pressure decreases further, and as the brake negative pressure becomes lower than the predetermined negative pressure, motoring is performed by the HCU 13 (marked as "ON" in the figure), and at time t5, the brake negative pressure is restored, and motoring is terminated by the HCU 13 (marked as "OFF" in the figure).

[0037] During the period from time t4 to time t5 during which motoring is being performed, the brake negative pressure recovers, and the amount of oxygen charged increases due to the air sent into the catalytic converter 10 by the engine 2 idling during motoring.

[0038] Similarly, the oxygen filling amount increases during the period from time t6 to time t8 when motoring is being performed, and during the period from time t9 to time t10 when motoring is being performed.

[0039] In this embodiment, motoring is started based on a predetermined negative pressure, and motoring ends when the brake negative pressure reaches a negative pressure at which it is determined that recovery has occurred, so the motoring execution times from time t4 to time t5, from time t6 to time t8, and from time t9 to time t10 are all equal to each other.

[0040] In this way, the amount of oxygen increases each time motoring is performed, and in the example shown in Fig. 2, there is an excess of oxygen in the catalytic device 10 at time t7. When there is an excess of oxygen in the catalytic device 10, the NOx reduction performance of the catalytic device 10 at the start of the engine 2 (hereinafter simply referred to as "engine start") decreases.

[0041] In order to suppress a decrease in the NOx reduction performance of the catalytic device 10 when the engine is started, it is necessary to increase the amount of fuel supplied to the engine 2 from the injector 31 when the engine is started (hereinafter simply referred to as the "fuel injection amount"), thereby promoting the oxidation of HC and CO within the catalytic device 10 and reducing the amount of oxygen stored.

[0042] That is, when the catalytic converter 10 contains an excess of oxygen at engine start, it is necessary to supply more fuel to the engine 2 than when the catalytic converter 10 does not contain an excess of oxygen.

[0043] As can be seen from Fig. 2, the number of times motoring is performed is uniquely determined experimentally or theoretically based on brake information. For example, as shown in Fig. 3(a), if the brake pedal 16 is operated six times (ON, OFF in the figure) from when the engine 2 stops at time t0 to when the engine 2 starts at time tf, motoring is performed three times.

[0044] As shown in FIG. 3(b), if the brake pedal 16 is operated five times between the time t0 when the engine 2 is stopped and the time tf when the engine 2 is started, motoring is performed two times.

[0045] As shown in FIG. 3(c), if the brake pedal 16 is operated four times between the time when the engine 2 is stopped at time t0 and the time when the engine 2 is started at time tf, motoring is performed two times.

[0046] As shown in FIG. 3(d), when the brake pedal 16 is operated three times between the time when the engine 2 is stopped at time t0 and the time when the engine 2 is started at time tf, one motoring is performed.

[0047] Thus, in this embodiment, if the brake pedal 16 is not operated or is operated once during the period from when the engine 2 is stopped at time t0 to when the engine 2 is started at time tf, motoring is not performed, if the brake pedal 16 is operated two or three times, motoring is performed once, if the brake pedal 16 is operated four or five times, motoring is performed two times, and if the brake pedal 16 is operated six or seven times, motoring is performed three times. That is, in this embodiment, motoring is performed every time the brake pedal 16 is operated two times during the period when the engine 2 is stopped.

[0048] As described above, each time motoring is performed, the amount of oxygen increases and the NOx reduction performance decreases. Therefore, when the engine is started, the HCU 13 adjusts the amount of fuel injection in accordance with the number of times the brake pedal 16 is operated while the engine 2 is stopped.

[0049] For example, among the examples shown in Figures 3(a) to 3(d), the fuel injection amount at time tf is the highest in the example shown in Figure 3(a), decreases in the examples shown in Figures 3(b) and 3(c), and then decreases in the example shown in Figure 3(d), and is the same in the examples shown in Figures 3(b) and 3(c).

[0050] Here, if a reference amount is set for the fuel injection amount at time tf, the fuel injection amount at time tf in the example shown in FIG. 3(a) is increased by a larger amount of fuel than the reference amount (indicated as "Fuel increase: large" in the figure).

[0051] Similarly, the amount of fuel injected at time tf in the examples shown in Figures 3(b) and 3(c) is increased by a small amount of fuel compared to the reference amount (indicated as "Fuel increase: small" in the figures), and the amount of fuel injected at time tf in the example shown in Figure 3(d) is not increased compared to the reference amount (indicated as "Fuel increase: none" in the figure).

[0052] As described above, the transition of the brake negative pressure is experimentally or theoretically uniquely determined from the brake information, and the number of times motoring is performed is experimentally or theoretically uniquely determined from the transition of the brake negative pressure.

[0053] In addition, the amount of air sent into the catalytic converter 10 by motoring is experimentally or theoretically uniquely determined from the number of times motoring is performed. In addition, the amount of oxygen filled in the catalytic converter 10 is experimentally or theoretically uniquely determined from the amount of air sent into the catalytic converter 10 by motoring.

[0054] In addition, the amount of fuel injection adjustment for appropriately treating exhaust gas when starting the engine (hereinafter simply referred to as the "appropriate fuel adjustment amount") is uniquely determined experimentally or theoretically from the oxygen charge amount. Therefore, the appropriate fuel adjustment amount is uniquely determined experimentally or theoretically from the brake information.

[0055] A brake negative pressure map in which brake information and brake negative pressure are associated with each other is stored in the ROM of the HCU 13. The HCU 13 refers to the brake negative pressure map and estimates the brake negative pressure based on the brake information.

[0056] A start fuel adjustment map in which brake information and appropriate fuel adjustment amounts are associated with each other is stored in the ROM of the HCU 13. The HCU 13 refers to the start fuel adjustment map and adjusts the fuel injection amount at engine start based on the brake information.

[0057] As described above, the brake negative pressure map experimentally or theoretically associates the brake information with the brake negative pressure, while the start fuel adjustment map experimentally or theoretically associates the brake information with the appropriate fuel adjustment amount.

[0058] For this reason, the brake negative pressure map and the starting fuel adjustment map are determined taking into consideration the various performances of the engine 2, the brake booster 12, the MG1 and the catalytic converter 10, as well as the predetermined negative pressure.

[0059] The engine stop operation of the HCU 13 configured as above will be described with reference to Fig. 4. The engine stop operation described below is executed when the engine 2 is stopped.

[0060] First, in S1, the HCU 13 updates brake information. After executing the process of S1, the HCU 13 executes the process of S2. In S2, the HCU 13 estimates a brake negative pressure based on a brake negative pressure map, and determines whether the estimated brake negative pressure is lower than a predetermined negative pressure.

[0061] If it is determined in S2 that the brake negative pressure is lower than the predetermined negative pressure, the HCU 13 executes the process of S3. If it is determined in S2 that the brake negative pressure is not lower than the predetermined negative pressure, the HCU 13 executes the process of S4.

[0062] In S3, the HCU 13 executes motoring. After executing the process of S3, the HCU 13 executes the process of S2. In S4, the HCU 13 determines whether or not a condition for starting the engine 2 (hereinafter, referred to as an "engine start condition") is satisfied.

[0063] For example, the engine start condition is satisfied when the state of charge of the battery 3 becomes lower than a predetermined lower limit state of charge. If it is determined in S4 that the engine start condition is satisfied, the HCU 13 executes the process of S5. If it is determined in S4 that the engine start condition is not satisfied, the HCU 13 executes the process of S1.

[0064] In S5, the HCU 13 adjusts the fuel injection amount at the time of starting the engine based on the start fuel adjustment map. After executing the process of S5, the HCU 13 executes the process of S6. In S6, the HCU 13 starts the engine 2.

[0065] When starting the engine 2, the HCU 13 controls the first inverter 5 to drive the MG1 to rotate the crankshaft of the engine 2, and controls the injector 31 to supply the fuel injection amount adjusted by the adjustment amount determined in S5 to the engine 2. After executing the process of S6, the HCU 13 executes the process of S7.

[0066] In S7, the HCU 13 initializes the brake information. After executing the process of S7, the HCU 13 ends the engine stop operation.

[0067] As described above, the vehicle control device of this embodiment adjusts the fuel injection amount at engine start, which is uniquely determined from the braking information during the period when the engine 2 is stopped, and therefore can appropriately treat the exhaust gas when the engine 2 is started.

[0068] Furthermore, since the vehicle control device of this embodiment estimates the brake negative pressure, which is uniquely determined from the brake information during the period when the engine 2 is stopped, even if there is a malfunction in the negative pressure sensor that detects the brake negative pressure, the brake negative pressure can be estimated, and the exhaust gas when the engine 2 is started can be appropriately treated according to the brake negative pressure.

[0069] In addition, since the vehicle control device of this embodiment adjusts the fuel injection amount at engine start, which is uniquely determined from braking information during the period when engine 2 is stopped, even if there is a malfunction in the O2 sensor (oxygen concentration sensor) installed in the exhaust passage, the exhaust gas when engine 2 is started can be appropriately treated according to the amount of oxygen present.

[0070] In this embodiment, the brake information is described as a time series of the operation state of the brake pedal 16. However, the brake information may be a time series of the brake stroke indicating the amount of operation of the brake pedal 16 and the hydraulic pressure in the master cylinder included in the hydraulic circuit 11b, in addition to the operation state of the brake pedal 16.

[0071] By configuring the brake information in this manner, the vehicle control device of this embodiment can more precisely adjust the fuel injection amount at engine start-up, thereby more appropriately treating exhaust gases when engine 2 is started.

[0072] Furthermore, by providing the brake information that represents the brake stroke and the oil pressure in the master cylinder in a time series in addition to the operation state of the brake pedal 16, the vehicle control device of this embodiment can more appropriately handle the exhaust gas when the engine 2 is started, even if there is a malfunction in the negative pressure sensor.

[0073] As described above, the number of times motoring is performed is uniquely determined experimentally or theoretically from the change in brake negative pressure, the amount of air sent into the catalytic device 10 by motoring is uniquely determined experimentally or theoretically from the number of times motoring is performed, the amount of oxygen charged is uniquely determined experimentally or theoretically from the amount of air sent into the catalytic device 10 by motoring, and the appropriate amount of fuel adjustment is uniquely determined experimentally or theoretically from the amount of oxygen charged.

[0074] Therefore, the appropriate fuel adjustment amount is uniquely determined experimentally or theoretically from the transition of the brake negative pressure. Therefore, the vehicle control device according to this embodiment may be configured to adjust the fuel injection amount at the time of engine start according to an integrated value of the reduction amount of the brake negative pressure during the period when the engine 2 is stopped (hereinafter, simply referred to as "integrated value of reduction in brake negative pressure").

[0075] In other words, instead of a start-up fuel adjustment map in which brake information corresponds to an appropriate fuel adjustment amount, a start-up fuel adjustment map in which a brake negative pressure reduction integrated value corresponds to an appropriate fuel adjustment amount may be stored in the ROM of HCU13, and HCU13 may refer to the start-up fuel adjustment map and adjust the fuel injection amount at engine start based on the brake negative pressure reduction integrated value.

[0076] In the present embodiment, an example has been described in which the vehicle control device according to the present invention is mounted on a vehicle 1 in which an engine 2 is provided for generating electricity. In contrast, the vehicle control device according to the present invention can be mounted on a vehicle having a configuration different from that of the vehicle 1, as long as the engine crankshaft can be rotated by a motor with the power transmission path between the engine and the drive wheels disconnected.

[0077] While the present invention has been disclosed by way of example, it will be apparent that modifications may be made to the present invention without departing from the spirit and scope of the present invention, and the present invention is disclosed with the understanding that equivalents of such modifications are intended to be included within the scope of the invention as defined by the appended claims. [Explanation of symbols]

[0078] 1 vehicle 2 Engine 4. First motor (motor) 11 Brake system 12 Brake booster 12a Negative pressure chamber 40 Control section 41 Brake information storage unit

Claims

1. The engine, a motor coupled to the engine; A brake device; a brake booster that boosts the braking force of the brake device by using an intake negative pressure of the engine, A vehicle control device including a control unit that, when a negative pressure in a negative pressure chamber of the brake booster becomes lower than a predetermined negative pressure, drives the motor to rotate the engine and restore negative pressure in the negative pressure chamber, a brake information storage unit that stores brake information indicating an operating state of the brake device during a period when the engine is stopped, The control unit adjusts a fuel injection amount of the engine in response to the brake information stored in the brake information storage unit when the engine is started.

2. 2. The vehicle control device according to claim 1, wherein the control unit estimates the negative pressure in the negative pressure chamber in accordance with the brake information stored in the brake information storage unit.

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