JP5884289B2 - Control device for hybrid vehicle - Google Patents

Description

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

  As an engine, a gaseous fuel engine to which a gaseous fuel such as hydrogen or LPG is supplied has been put into practical use. In addition, the number of hybrid vehicles equipped with an engine and a driving motor tends to increase. Patent Document 1 discloses an engine for a hybrid vehicle. A gas fuel engine is disclosed. Patent Document 2 discloses that in a hybrid vehicle, engine rotation is performed within a high efficiency range.

  On the other hand, recent engines are increasing in number that automatically stop and start the engine. For example, when the engine is mounted on a vehicle that performs idling stop or a hybrid vehicle, the engine is automatically stopped and started. In such an automatic engine stop and start, automatic start is performed quite frequently, so that the battery power consumption required for engine cranking increases (battery Burden).

JP 2006-250024 A JP 2007-195334 A

  By the way, in a hybrid vehicle, the importance of a battery is extremely high, and it is strongly desired to perform charging and discharging particularly efficiently. On the other hand, the charge / discharge efficiency of the battery is greatly reduced when the battery temperature is low. That is, for example, when the vehicle starts running from a state where the battery temperature is lowered due to being left for a long time in an environment where the outside air temperature is low, the battery temperature will not rise sufficiently unless the vehicle is driven for a considerably long time. In the meantime, charging or discharging is performed in a state where charging / discharging efficiency is poor, and fuel consumption is deteriorated by the amount of the charging / discharging efficiency being poor.

  The present invention has been made in view of the circumstances as described above, and an object of the present invention is to provide a control device for a hybrid vehicle capable of promptly raising the battery temperature.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 1 in the claims,
An engine, a generator that is driven by the engine to generate electric power, a battery that stores electric power generated by the generator, and a traveling motor that is driven by receiving electric power from at least one of the battery and the generator, A hybrid vehicle control device comprising:
Temperature detecting means for detecting the temperature of the battery;
A first fuel injection valve that injects fuel toward the intake port;
A second fuel injection valve that directly injects fuel into the cylinder;
When the temperature detected by the temperature detecting means is equal to or lower than a predetermined temperature set in advance, the generator periodically changes the engine output while keeping the engine speed within a constant rotation range, thereby discharging and charging the battery. Control means to be repeated periodically;
Bei to give a,
Fuel supplied to the engine is gaseous fuel,
When the accelerator opening is equal to or greater than a predetermined value, the control means increases or decreases the fuel injection amount while changing the engine output to a fully-open throttle state in which there is almost no differential pressure across the throttle valve. The engine output is increased due to the periodic change of the air-fuel ratio, and the generator is caused to generate power to be consumed by charging the battery, while the decrease in engine output is consumed by the battery. The engine speed is maintained in the constant rotation range by discharging from
When the accelerator opening is smaller than the predetermined value, the control means maintains the air-fuel ratio at the predetermined air-fuel ratio, and periodically changes the engine output from the first fuel injection valve during the intake stroke. The fuel injection mode is performed by periodically changing the ratio between the first fuel injection mode for fuel injection and the second fuel injection mode for fuel injection from the second fuel injection valve in the range from the end of the intake stroke to the compression stroke. An increase in engine output accompanying a periodic change in power is generated by generating the generator and charging the battery, while a decrease in engine output is discharged from the battery to reduce the engine speed to the constant rotation range. To maintain,
It is Unishi.

According to the above solution, since charging and discharging of the battery are repeatedly performed, the battery temperature is quickly raised, and the charge / discharge efficiency of the battery is increased early. In addition, the change in the engine speed accompanying the fluctuation in the engine output is consumed by charging the battery by the power generation of the generator for the increase in the engine output, while the decrease in the engine output is compensated by the discharge from the battery. This prevents the passenger from feeling uncomfortable.

In addition, the engine output is periodically changed when the accelerator opening is greater than or equal to a predetermined value by reducing the pumping loss and the air-fuel ratio is periodically changed to significantly change the engine output and prevent deterioration of fuel consumption. Or it becomes a preferable thing on suppression.

Furthermore, since the fuel is a gaseous fuel by performing a periodic change of the engine output when the accelerator opening is smaller than a predetermined value by changing the fuel injection mode while maintaining the air-fuel ratio at the predetermined air-fuel ratio, The engine output can be largely changed between the first fuel injection mode and the second fuel injection mode.

  ADVANTAGE OF THE INVENTION According to this invention, the temperature of a battery can be raised promptly and the state where the charging / discharging efficiency of a battery becomes high can be ensured promptly.

The simplified top view which shows an example at the time of applying this invention to a hybrid vehicle. The system diagram which shows an example of a gaseous fuel engine. The figure which shows an example when driving | running | working, using the driving | running | working using only battery power, and generating electric power with an engine. The figure which shows the example of a control system of this invention in a block diagram. The time chart which shows a mode when engine output is changed periodically by the change of a fuel-injection aspect. The time chart which shows a mode when engine output is changed periodically by the change of an air fuel ratio. The flowchart which shows the example of control of this invention.

  In FIG. 1, an automobile V as a vehicle has a body (vehicle body) indicated by reference numeral 1, left and right front wheels indicated by reference numeral 2, and left and right rear wheels indicated by reference numeral 3. A traveling motor 4 is connected to the left and right front wheels 2 via a differential gear 5A and a drive shaft 5B. In other words, in the embodiment, a front-wheel drive vehicle in which only the left and right front wheels 2 are driven.

  In addition to the traveling motor 4, an engine 6, a generator 7, and an inverter 8 are disposed at the front portion of the body 1. A battery 9 and a fuel tank 10 are disposed below the floor surface of the body 1 from the middle part in the front-rear direction to the rear part. The engine 6 is a spark-ignition gas fuel engine, and is supplied with, for example, hydrogen as a gaseous fuel stored in the fuel tank 10.

  The generator 7 is driven by the engine 6 to generate electric power, and also functions as a starting motor for starting the engine 6 by receiving electric power from the battery 9. The battery 9 is composed of, for example, a lithium ion battery, and has a high voltage (for example, 300 to 500 V) and a large capacity. The electric power stored in the battery 9 is supplied to the traveling motor 4 and travels, and the electric power stored only in the battery 9 in the maximum power storage state can travel several tens km (for example, 30 to 60 km). Further, a low-voltage (for example, 12V) battery 11 is mounted on the rear end of the body 1, and this battery 11 is used for various on-vehicle electric devices such as a spark plug, a fuel injection valve, a headlight, a wiper, and an audio. Power is supplied.

  FIG. 2 shows an example of the engine 6 and its intake / exhaust system. In the embodiment, the engine 6 is a Wankel type rotary piston engine, and has two cylinders of a first cylinder RA and a second cylinder RB in series. Branch intake passages 21A and 21B that are individually connected to the intake ports of the cylinders RA and RB are connected to one common intake passage 22. A throttle valve 23 is disposed in the common intake passage 22. Further, first fuel injection valves 24A and 24B for port injection are disposed in the respective branch intake passages 21A and 21B. The first fuel injection valves 24A and 24B are for obtaining a first fuel injection mode in which fuel is injected during the intake stroke. As the fuel injection valve, second fuel injection valves 25A and 25B that directly inject fuel into the cylinder (working chamber) are further provided. The second fuel injection valves 25A and 25B perform fuel injection in the range from the end of the intake stroke to the compression stroke (in the embodiment, fuel injection is performed during the compression stroke), and a second fuel injection mode is obtained. It has become a thing.

  Branch exhaust passages 26 </ b> A and 26 </ b> B that are individually connected to the exhaust ports of the cylinders RA and RB are connected to one common exhaust passage 27. An air-fuel ratio sensor 28 is disposed in the common exhaust passage 27, and an exhaust gas purification catalyst (NOx catalyst in the embodiment) 29 is disposed on the downstream side of the air-fuel ratio sensor 28.

  The common intake passage 22 and the common exhaust passage 27 are connected by an EGR passage 30, and an EGR valve 31 is connected to the EGR passage 30. The EGR passage 30 is opened to the common intake passage 22 on the downstream side of the throttle valve 23, and is opened to the common exhaust passage 27 on the upstream side of the air-fuel ratio sensor 28.

  Each cylinder RA, RB has two spark plugs 33A, 33B. After the engine is started, fuel injection from the first fuel injection valves 24A and 24B is executed at a relatively low rotation and low load, while fuel injection from the second fuel injection valves 25A and 25B is relatively Performed at high rotation or high load. A mixture of air and hydrogen as fuel injected from the fuel injection valve is ignited by the spark plugs 33A and 33B. Combustion is performed by igniting the air-fuel mixture.

  FIG. 3 shows how the traveling state of the vehicle V is changed according to the amount of power stored in the battery 9. That is, when the charged amount of the battery 9 is large (for example, until the charged amount is reduced to 40%), the engine 6 is stopped (automatically stopped), and the traveling motor 4 is driven only by the power supply from the battery 9. (So-called plug-in travel). On the other hand, when the storage amount of the battery 9 is small (for example, when the storage amount is less than 40%), the engine 6 is started (automatic start), and the generator 7 generates power, and the generator 7 generates power. Electric power is supplied to the traveling motor 4 and surplus power is supplied to the battery 9. When the amount of electricity stored in the battery 9 is increased by the power generated by the generator 7 (for example, when the amount of electricity stored reaches 70%), the engine 4 is automatically stopped (resumption of plug-in travel). As described above, the engine 6 automatically repeats stop and start according to the amount of power stored in the battery 9, and when the engine 6 is started, the generator 7 generates power and travels and stores power in the battery 9. Is done. Note that when the vehicle V is decelerated, regeneration is performed by the traveling motor 4, and electric power generated by regeneration is stored in the battery 9.

  FIG. 4 is a block diagram showing an example of the control system of the present invention. In the figure, U is a controller (control unit) configured using a microcomputer. The controller U controls the traveling motor 4, the engine 6 (particularly the fuel injection valve), the generator 7, and the inverter 8. Power transfer between the battery 9 and the travel motor 4 via the inverter 8, power transfer between the generator 7 and the battery 9, power supply from the generator 7 to the travel motor 4, and from the battery 9 to the battery 11 is supplied with electric power.

  The controller U performs engine control such as fuel injection control and ignition timing control, performs automatic stop and start control of the engine 6, and also performs rapid temperature rise control of the battery 9, which will be described later. A signal from the air-fuel ratio sensor 28 is input to the controller U. The air-fuel ratio sensor 28 is a linear sensor and detects an excess air ratio λ as an air-fuel ratio. In addition, the controller U receives signals from various sensors or switches S1 to S6. The sensor S1 detects the vehicle speed. The sensor S2 detects the accelerator opening. The sensor S3 detects the temperature of the battery 9. The sensor S4 detects the engine speed. The switch S5 detects that the brake pedal has been depressed. The sensor S6 detects the amount of charge of the battery 9. The sensor S3 for detecting the temperature of the battery 9 may directly detect the temperature of the battery 9. For example, the sensor S3 detects the magnitude of the current flowing through the battery 9 under a predetermined condition. In other words, the battery temperature may be indirectly detected.

  The automatic stop and automatic start of the engine 6 by the controller U are performed according to the following conditions, for example. First, as described above, automatic stop and automatic start according to the charged amount of the battery 9 are performed. Even under the condition that the engine is automatically started according to the amount of power stored in the battery 9, automatic stop and automatic start by idle stop are performed. That is, for example, when the accelerator opening is 0, the vehicle speed is 0, and the brake switch S5 is ON (when the brake pedal is depressed), the engine 6 is automatically stopped. When the brake switch S5 is turned off from the automatic stop state, the engine 6 is automatically started.

  Next, referring to FIG. 5, a control example of a rapid temperature rise of the battery 9 when the temperature of the battery 9 is low (for example, 10 degrees C or less) will be described. For example, it is assumed that the accelerator opening is less than 50%). In the example of FIG. 5, the fuel injection mode is periodically changed. That is, the mode in which fuel injection (port injection) is performed from the first fuel injection valves 24A and 24B during the intake stroke is referred to as a first fuel injection mode, and the second fuel injection valves 25A and 25B in the range from the end of the intake stroke to the compression stroke are used. When the second fuel injection mode is used as the fuel injection (direct injection), the fuel injection in the first fuel injection mode and the fuel injection in the second fuel injection mode are periodically switched. The engine speed fluctuation caused by the engine output fluctuation is controlled by the generator 7 so that the engine speed is within a certain speed range (for example, fluctuation within a range of ± 50 rpm), and the battery 9 is charged / discharged. To be suppressed.

  Specifically, at the normal time, the fuel injection ratio between the first fuel injection mode and the second fuel injection mode is set to, for example, 50%. When the engine output is increased, the fuel injection ratio in the first fuel injection mode is decreased from 50% in the normal state, while the ratio in the second fuel injection mode is increased from 50% in the normal state (for example, the first fuel injection mode). The fuel injection ratio in the first fuel injection mode is 30%, and the fuel injection ratio in the second fuel injection mode is 70%). In the first fuel injection mode, the charging efficiency is lower than that in the second fuel injection mode. Therefore, by reducing the fuel injection rate in the first fuel injection mode and increasing the fuel injection rate in the second fuel injection mode, the charging efficiency is improved and the engine output is increased. Become. In particular, in the case of gaseous fuel, the difference in charging efficiency between the first fuel injection mode and the second fuel injection mode is greater than in the case of liquid fuel.

  When the engine output is reduced, contrary to the above, the fuel injection ratio in the first fuel injection mode is increased from 50% of the normal time, while the ratio of the second fuel injection mode is increased from 50% of the normal time. (For example, the fuel injection ratio in the first fuel injection mode is 70%, and the fuel injection ratio in the second fuel injection mode is 30%). When changing the fuel injection ratio in the two fuel injection modes, it can be set such that one of the fuel injection ratios is 0% (the other is 100%).

  The engine speed fluctuation that is caused by the fluctuation of the engine output due to the change of the fuel injection ratio in the two fuel injection modes is prevented or suppressed by the generator 7 so that the engine speed falls within the constant speed range. It is controlled to become. That is, when the engine output is increased, the surplus output with respect to the output necessary for maintaining the constant rotational speed is consumed for power generation of the generator 7, and at this time, the battery 9 is charged. On the contrary, when the engine output decreases, the battery 9 is discharged by the insufficient output necessary for maintaining the engine speed. By repeating the charging and discharging of the battery 9 as described above, the temperature of the battery 9 is quickly raised. In FIG. 5, the engine output is increased until the time t1 and between the time t2 and the time t3, and the battery 9 is charged. Further, the engine output is reduced between time t1 and time t2 and between time t3 and time t4, and the battery 9 is discharged.

  FIG. 6 shows an example in which the battery 9 is repeatedly charged and discharged by periodically changing the air-fuel ratio on the assumption that the engine load is large (for example, the accelerator opening is 50% or more). That is, the engine output is changed periodically by changing the air-fuel ratio periodically without changing the fuel injection ratio between the first fuel injection mode and the second fuel injection mode (for example, by 50%). It is. Of course, the generator 7 is controlled so that the engine speed is in a certain range, and the battery 9 is repeatedly charged and discharged. In the case of FIG. 6, the air-fuel ratio at the normal time is, for example, the excess air ratio λ is 2.2, and when the engine output is increased, the air-fuel ratio is made rich (for example, λ is 2.0) and the output output is decreased. In some cases, the air-fuel ratio is made lean (for example, λ is 2.4). The excess air ratio λ can be set as appropriate within a range of 1.0 or more.

  In FIG. 6, the air-fuel ratio is made rich until the time t11 and between the time t12 and the time t13, and the battery 9 is charged. Further, the air-fuel ratio is made lean between time t11 and time t12 and between time t13 and time t14, and the battery 9 is discharged. By repeating charging / discharging of the battery 9 as described above, the temperature of the battery 9 is quickly raised while the engine speed is kept within a constant speed range.

  FIG. 7 is a flowchart showing an example of control of the battery temperature rise by the controller U. This flowchart will be described below. In the following description, Q indicates a step. First, in Q1, signals from various sensors or switches S1 to S6 are read. Next, at Q2, it is determined whether or not the temperature of the battery 9 detected by the sensor S3 is equal to or lower than a predetermined temperature (10 degrees C in the embodiment). When the determination in Q12 is NO, it is determined that the control for positively increasing the temperature of the battery 9 is not necessary, and the routine proceeds to Q12 and normal operation is performed (for example, the first fuel injection mode and the inner two fuels). The fuel injection ratio in the injection mode is 50% and the air-fuel ratio is λ = 2.2).

  If the determination in Q2 is YES, it is determined in Q3 whether the accelerator opening is at a low load of less than 50%. When the determination in Q3 is YES, the engine output is periodically changed by periodically changing the fuel injection ratio between the first fuel injection mode and the second fuel injection mode by the processing of Q5 or less. The battery 9 is repeatedly charged and discharged. That is, in Q4, the change control of the fuel injection ratio is selected. Initially, in Q5, only the first fuel injection mode is set (intake stroke injection), and the battery 9 is discharged. Thereafter, at Q6, the discharge current of the battery 9 is read. Thereafter, in Q7, it is determined whether or not a predetermined time (for example, 10 seconds to 20 seconds) has elapsed since the start of fuel injection in only the first fuel injection mode. If the determination in Q7 is NO, the process returns to Q5.

  If the determination in Q7 is YES, in Q8, fuel injection is performed only in the second fuel injection mode (only direct injection in the range from the end of the intake stroke to the compression stroke), and the battery 9 is charged. Thereafter, after the magnitude of the charging current is read in Q9, whether or not a predetermined time (for example, 10 to 20 seconds) has elapsed since the start of fuel injection only in the second fuel injection mode in Q10. Is determined. If the determination in Q10 is NO, the process returns to Q8.

  If the determination in Q10 is YES, it is determined in Q11 whether or not the temperature of the battery 9 has exceeded a predetermined temperature. If the determination in Q11 is NO, the process returns to Q3. If YES in Q11, the process proceeds to Q12 (returns to normal operation). The charging / discharging current reading in Q6 and Q9 is, for example, feedback control of the fuel injection ratio between the two fuel injection modes so that the charging / discharging current is within a predetermined range set in advance. Used for.

  When the determination in Q3 is NO, that is, when the engine load is large, the temperature increase control of the battery 9 is performed by controlling the air-fuel ratio fluctuation below Q13. That is, it is selected to execute the air-fuel ratio fluctuation control in Q13, and thereafter, in Q14, the air-fuel ratio is made lean (discharge of the battery 9). Thereafter, in Q15, after the discharge current of the battery 9 is read, it is determined in Q16 whether or not a predetermined time (for example, 10 to 20 seconds) has elapsed since the air-fuel ratio was made lean. If the answer to Q16 is NO, the process returns to Q14.

  If YES in Q16, the air-fuel ratio is made rich in Q17 and the battery 9 is charged. Thereafter, in Q18, after the magnitude of the charging current is read, in Q19, it is determined whether or not a predetermined time (for example, 10 to 20 seconds) has elapsed since the air-fuel ratio was made rich. If NO in Q19, the process returns to Q17.

  If YES in Q19, it is determined in Q11 whether the temperature of the battery 9 has exceeded a predetermined temperature. If the determination in Q11 is NO, the process returns to Q3. When YES is determined in Q11, the process proceeds to Q12 (return to normal operation). The reading of currents at Q15 and Q18 is used for feedback control of the degree of leanness or richness of the air-fuel ratio so that the charge / discharge current is within a predetermined range set in advance.

  Although the embodiment has been described above, the present invention is not limited to the embodiment, and can be appropriately changed within the scope described in the scope of claims. For example, the invention includes the following cases. . Wheel driving may be performed by the engine 6. In this case, wheel driving by only the engine 6, wheel driving by only the traveling motor 4, and wheel driving by both the engine 6 and the traveling motor 4 are possible. May be appropriately switched. The engine 6 may be a reciprocating engine, or may be supplied with liquid fuel such as gasoline or light oil. The change of the fuel injection ratio and the change of the air-fuel ratio in the two fuel injection states may be performed simultaneously (a larger output fluctuation can be performed). Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

  The present invention is suitable for application to a hybrid vehicle.

V: Vehicle 4: Driving motor 6: Engine 7: Generator 9: Battery 10: Fuel tank 24A, 24B: First fuel injection valve (first fuel injection mode)
25A, 25B: second fuel injection valve (second fuel injection mode)
28: Air-fuel ratio sensor 33A, 33B: Spark plug U: Controller S3: Sensor (battery temperature)

Claims (1)

An engine, a generator that is driven by the engine to generate electric power, a battery that stores electric power generated by the generator, and a traveling motor that is driven by receiving electric power from at least one of the battery and the generator, A hybrid vehicle control device comprising:
Temperature detecting means for detecting the temperature of the battery;
A first fuel injection valve that injects fuel toward the intake port;
A second fuel injection valve that directly injects fuel into the cylinder;
When the temperature detected by the temperature detecting means is equal to or lower than a predetermined temperature set in advance, the generator periodically changes the engine output while keeping the engine speed within a constant rotation range, thereby discharging and charging the battery. Control means to be repeated periodically;
Bei to give a,
Fuel supplied to the engine is gaseous fuel,
When the accelerator opening is equal to or greater than a predetermined value, the control means increases or decreases the fuel injection amount while changing the engine output to a fully-open throttle state in which there is almost no differential pressure across the throttle valve. The engine output is increased due to the periodic change of the air-fuel ratio, and the generator is caused to generate power to be consumed by charging the battery, while the decrease in engine output is consumed by the battery. The engine speed is maintained in the constant rotation range by discharging from
When the accelerator opening is smaller than the predetermined value, the control means maintains the air-fuel ratio at the predetermined air-fuel ratio, and periodically changes the engine output from the first fuel injection valve during the intake stroke. The fuel injection mode is performed by periodically changing the ratio between the first fuel injection mode for fuel injection and the second fuel injection mode for fuel injection from the second fuel injection valve in the range from the end of the intake stroke to the compression stroke. An increase in engine output accompanying a periodic change in power is generated by generating the generator and charging the battery, while a decrease in engine output is discharged from the battery to reduce the engine speed to the constant rotation range. To maintain,
A control apparatus for a hybrid vehicle characterized by the above.

Images