JP2007238039A - Hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid vehicle that prevents driving performance from deterioration immediately after an engine operation region is switched from a partial load region to a high load region. <P>SOLUTION: The hybrid vehicle has a drive source including an engine 1 and a motor generator 4 for driving; and an electrically controlled thermostat 24 (cooling water temperature changing means) for switching the set temperature of cooling water in such a manner that when the engine operation region is the partial load region, the set temperature is a predetermined high water temperature, while when the engine operation region is the high load region, the set temperature is a predetermined low water temperature. When the engine operation region is switched from the partial load region to the high load region (S11), the shortage of internal combustion engine torque with respect to a requested load due to the high cooling water temperature is compensated by the motor torque of the motor generator 4 (S13) until the cooling water temperature drops to the predetermined low water temperature (S14). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hybrid vehicle including an internal combustion engine and a motor generator as drive sources.

  In Patent Document 1, the temperature of the cooling water is increased in the low load region, the temperature of the cooling water is decreased in the high load region, and the required output is output when the operation region is switched from the low load region to the high load region. A vehicle control device is disclosed in which a predetermined output is temporarily added to the engine to prevent a decrease in engine efficiency due to a delay in the response of the coolant temperature.

When the set temperature of the cooling water is increased in the low load region, the cooling is alleviated to reduce the heat loss and friction loss of the internal combustion engine, thereby improving the fuel efficiency. Further, if the set temperature of the cooling water is lowered in the high load region, knocking can be avoided by promoting the cooling.
JP 2004-204740 A

  However, in Patent Document 1, when the switching from the low load region to the high load region is performed, the cooling water does not immediately fall to a predetermined temperature, so that the target engine output cannot be obtained and the driver is not obtained. There is a risk of giving a sense of incongruity.

  And in patent document 1, when switching from a low load area to a high load area, in order to obtain a target engine output, it is necessary to set the temperature of the cooling water in the low load area low, There is a problem that it is impossible to improve fuel consumption.

  Further, as in Patent Document 1, when the cooling water is not immediately lowered to a predetermined temperature when switching from the low load region to the high load region, the compression ratio cannot be set high in the high load region. That is, in the first reference, when the compression ratio setting in the high load region is set to the high compression ratio setting in order to improve the thermal efficiency in a state where the cooling water does not completely fall to the predetermined temperature in the high load region, When switching from the load region to the high load region, there is a problem that the operation performance is deteriorated such that knocking is likely to occur until the cooling water is lowered to a predetermined temperature.

  Therefore, the present invention provides a drive source including an internal combustion engine and a motor generator, a set temperature of cooling water at a predetermined high water temperature when the engine operation region is a partial load region, and a set temperature of cooling water when the engine operation region is a high load region. In a hybrid vehicle having a cooling water temperature changing means for setting the cooling water temperature to a predetermined low water temperature, when the engine operation region is switched from the partial load region to the high load region, until the cooling water temperature reaches the predetermined low water temperature, The shortage of the internal combustion engine torque with respect to the required load caused by the high coolant temperature is compensated by the motor torque of the motor generator. If the set temperature of the cooling water is increased when the engine operating region is in the partial load region, the cooling is relaxed, so that heat loss, friction loss, etc. of the internal combustion engine are reduced and fuel efficiency is improved. Further, if the set temperature of the cooling water is lowered when the engine operation region is a high load region, knocking is avoided by promoting the cooling, and desired operation performance can be ensured.

  According to the present invention, in a state where the engine operation region is switched from the partial load region to the high load region and the cooling water temperature cannot be lowered to the predetermined low water temperature, the shortage of the engine torque (internal combustion engine torque) with respect to the required load is reduced by the motor generator. Therefore, it is possible to prevent deterioration of the operation performance immediately after the engine operation region is switched from the partial load region to the high load region.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory view schematically showing a schematic configuration of a hybrid vehicle to which the present invention is applied. This hybrid vehicle uses an engine 1 that is an internal combustion engine and motor generators 2 and 4 in combination as a drive source. The engine 1 generates driving force by burning fuel such as gasoline or light oil, and rotationally drives a crankshaft (first shaft) 1a. Each of the motor generators 2 and 4 is an AC motor generator connected to a battery 5 that stores electric power and a known inverter (not shown), and can perform both a power running operation and a regenerative operation. The power generation motor generator 2 functions mainly as a generator that generates power by being rotationally driven by the crankshaft 1a, and also functions as an engine starter motor that cranks the crankshaft 1a when the engine is started. The traveling motor generator 4 mainly functions as a traveling electric motor that rotationally drives the second shaft 7, and rotates the driving wheel 11 alone or in cooperation with the engine 1. As will be described later, the traveling motor generator 4 generates power by regenerative operation when the vehicle is decelerated.

  The driving force of the driving source is transmitted to a pair of driving wheels 11 via a reduction gear 6 such as a planetary gear 6, a stepped automatic transmission 8, a differential gear 9, and a drive shaft (third axis) 10. Is done. The automatic transmission 8 shifts (decelerates) the driving force of the driving source stepwise and transmits it to the driving wheel 11. For example, the automatic transmission 8 includes a plurality of forward gears (or four gears) including a plurality of planetary gear mechanisms, and the reverse gear 1. It is a well-known stepped automatic transmission with a stage.

  A clutch 3 for intermittently transmitting power is interposed between the engine 1 and the motor generator 2 for power generation, and the motor generator 4 for travel and the automatic transmission 8. The clutch 3 is a well-known hydraulic multi-plate clutch capable of changing and controlling the engagement rate and the slip rate continuously and continuously, and is a power generation motor generator 2 that rotates in synchronization with the crankshaft 1a of the engine 1. The rotating shaft is connected to the drive side. An input shaft (second shaft) 7 of a reduction gear 6 arranged coaxially with the crankshaft 1 a is connected to the driven side of the clutch 3, and a traveling motor generator 4 is connected to the other end of the input shaft 7. It is connected. The clutch 3 is engaged during engine travel, and the clutch 3 is disengaged during idling stop or motor travel.

  The control device 12 is a well-known microcomputer system having a CPU, ROM, RAM and an input / output interface, and includes a water temperature sensor 21, an engine speed sensor 22, an accelerator opening sensor 23 as a cooling water temperature detecting means, and an illustration. Based on detection signals of various sensors such as a vehicle speed sensor, a control signal is output to the engine 1, motor generators 2, 4, automatic transmission 8, and electric thermostat 24 as a coolant temperature changing means, and the operation is performed. Control. In addition, a signal from the battery controller 25 that detects the charge amount of the battery 5 is input to the control device 12.

  The control device 12 executes a program stored in advance on the ROM, thereby realizing a predetermined function by making use of functions and performance that each component is good at. For example, in order to mainly improve fuel efficiency and purify exhaust, the engine 1 is automatically stopped when the vehicle is temporarily stopped, such as waiting for an intersection, that is, idling stop is performed, and engine low-speed driving with poor engine efficiency is switched to motor driving. The efficiency of the engine operating point is increased by the automatic transmission 8, and the vehicle kinetic energy during vehicle deceleration and braking is regenerated by the motor generators 2 and 4. Among these functions, energy regeneration by the motor generator when the vehicle is decelerating effectively uses energy that was not used as brake heat in a vehicle that uses only the engine 1 as a power source. A big effect can be expected.

  Here, the control device 12 controls the opening / closing amount of the electric thermostat 24 according to the engine speed and the required load. More specifically, as shown in FIG. 2, the electric thermostat 24 switches the temperature of the cooling water between two levels of a predetermined low water temperature (for example, about 90 ° C.) and a predetermined high water temperature (for example, about 110 ° C.) An on-off valve (switching valve) controlled by the control device 12, and when the operation region (engine operation region) of the engine 1 is a partial load region (low load region), cooling water passing through the engine 1 is radiator (not shown). ) Is circulated to increase the water temperature, and when the operating region of the engine 1 is in a high load region, the cooling water that has passed through the engine 1 is circulated via a radiator (not shown) so as to have a low water temperature. This is because when the operating region of the engine 1 is a partial load region, by increasing the set temperature of the cooling water, the cooling of each part is alleviated and the heat loss, friction loss, etc. of the engine 1 are reduced and the fuel efficiency is improved. is there. In addition, when the operation region of the engine 1 is a high load region, by lowering the set temperature of the cooling water, the cooling of each part is promoted, knocking of the engine 1 is avoided, and the expected operation performance can be secured. .

  That is, in FIG. 2, when the temperature of the cooling water is a region where the temperature is high, the operation region of the engine 1 is a partial load region, and when the temperature of the cooling water is a region where the temperature is low, the operation region of the engine 1 Is the high load range.

  The required load in this embodiment is determined according to the accelerator opening (APO), that is, the detected value of the accelerator opening sensor 23.

  And in the hybrid vehicle to which the present invention is applied, when the operation region of the engine 1 is switched from the partial load region to the high load region, the cooling water temperature is changed from the predetermined high water temperature to the predetermined low water temperature. The shortage of the engine torque (internal combustion engine torque) with respect to the required load caused by the high coolant temperature is compensated by the motor torque of the motor generator 4 for traveling.

  FIG. 3 shows the cooling water temperature, the engine torque of the engine 1 and the motor of the motor generator 4 when the required load is changed from the partial load to the high load and the operation region of the engine 1 is switched from the partial load region to the high load region. It is a timing chart which shows the state change of a torque.

  As shown in FIG. 3, the engine torque generated in the engine 1 starts to increase with the increase in the required load at time t1, but cannot keep up with the required load because the cooling water temperature is high. That is, the required load is switched from the partial load to the high load between time t1 and time t2, and the operation region of the engine 1 is also switched from the partial load region to the high load region, but the engine torque has a high coolant temperature at the time t2. In addition, the desired magnitude is not reached, and gradually changes to the desired magnitude as the cooling water temperature decreases after time t2, and the desired magnitude is reached at time t3 when the cooling water temperature reaches a predetermined low water temperature. It becomes. In other words, the engine torque continues to increase to a desired magnitude commensurate with the required load even after the operation region of the engine 1 is switched, so the engine torque response is poor and On the other hand, it will give an uncomfortable feeling.

  Therefore, in the present embodiment, when the operation region of the engine 1 is switched from the partial load region to the high load region, the required load generated because the cooling water temperature is high until the cooling water temperature becomes a predetermined low water temperature. By compensating the shortage of the engine torque with respect to the motor torque of the motor generator 4, the responsiveness to the required load is improved as the entire drive source of the hybrid vehicle. Specifically, from time t2 to time t3, the motor generator 4 generates motor torque for driving the vehicle, and at time t2, the torque corresponding to the required load is generated by the engine 1 and the motor generator 4. The motor torque applied from the motor generator 4 between times t2 and t3 is set so as to decrease as the temperature difference between the cooling water temperature detected by the water temperature sensor 21 and the predetermined low water temperature decreases, and the engine 1 and the engine torque are set to be constant.

  Further, the difference in the engine torque with respect to the required load is such that the torque difference with respect to the temperature difference of the cooling water (the difference between the predetermined low water temperature and the water temperature detected by the water temperature sensor 21) increases as the engine speed decreases and the load increases. This torque difference corresponds to the motor torque of the motor generator 4 that compensates for the shortage of the engine torque. For example, a map that can be calculated using the current engine torque and the coolant temperature is prepared in advance by experiment fitting or the like, and the torque difference is calculated using this map.

  In this embodiment, even when the operating range of the engine 1 is in the partial load range, even if the cooling water temperature is set to a high water temperature with an emphasis on fuel efficiency, the operating range of the engine 1 is in the partial load range. When the engine is switched from the high load range to the high load range, the engine torque deficiency is compensated for by the motor torque until the cooling water temperature decreases to the low water temperature. It is possible to achieve both improvement in fuel efficiency and securing of driving performance in a high load range, and realize a shift from a partial load range to a high load range in the driving range of the engine 1 without giving the driver a sense of incongruity. be able to.

  In addition, the above-described control can cover a decrease in volumetric efficiency when the cooling water is at a high water temperature and a decrease in throttle full opening performance (high load operation performance) due to a deterioration in knocking characteristics. Therefore, it is necessary to increase the torque in the engine 1. Therefore, even when the fuel injection amount is corrected to increase when the coolant temperature is high, the fuel consumption can be improved without increasing the fuel injection amount as compared with the conventional engine.

  And when the operation area of the engine 1 is switched from the partial load area to the high load area, the shortage of the engine torque is temporarily compensated by the motor torque of the motor generator 4, so that the burden on the battery 5 also becomes a problem. There is nothing.

  FIG. 4 is a flowchart showing the control flow of the present embodiment described above.

  In step (hereinafter abbreviated as S) 11, it is determined from the required load (APO) and the engine speed whether or not the temperature range of the cooling water is switched from the high water temperature region to the low water temperature region. If the water temperature region is switched to the low water temperature region, the process proceeds to S12, and if not, the process proceeds to S15.

  In S12, the electric control thermostat 24 is switched so that the temperature setting of the cooling water becomes a predetermined low water temperature.

  In S <b> 13, the shortage of the engine torque with respect to the required load (APO) is assisted by the motor torque of the motor generator 4.

  In S14, it is determined whether or not the cooling water temperature has decreased to a predetermined low water temperature. If it is determined that the cooling water temperature has not decreased to the predetermined low water temperature, the process returns to S13, and the engine torque is insufficient. Is assisted by motor torque. If it is determined that the cooling water temperature has decreased to a predetermined low water temperature, the current routine is terminated.

  On the other hand, in S15, it is determined from the required load (APO) and the engine speed whether or not the cooling water temperature region has been switched from the low water temperature region to the high water temperature region, and the cooling water temperature region is switched from the low water temperature region to the high water temperature region. If the area has been switched, the process proceeds to S16, and if not, the current routine is terminated.

  In S16, the electric thermostat 24 is switched so that the temperature setting of the cooling water becomes a predetermined high water temperature.

  In the above-described embodiment, the remaining amount of the battery 5 is monitored, and the amount of charge of the battery 5 becomes equal to or less than a preset threshold value. If it cannot be compensated for, even if the required load is in the partial load region, the electric thermostat 24 is controlled so that the temperature of the cooling water becomes low, and the throttle full open performance (high load operation performance) is reduced. May be prevented.

  Further, when the driver intends to achieve fuel-efficient driving, the electric thermostat 24 may be controlled so that the temperature of the cooling water becomes a low water temperature regardless of the driving state. In this case, it is determined by the driver intention determination means whether or not the driver desires fuel-efficient driving. As a specific example of the driver intention determination means, it is estimated that a fuel-efficient driving is desired when a switch that is directly operated by the driver is provided or when the driver's acceleration / deceleration request is not severe due to the depression of the accelerator pedal. May be.

  The technical idea of the present invention that can be grasped from the above embodiment will be listed together with the effects thereof.

  (1) A drive source including an internal combustion engine and a motor generator, and a set temperature of cooling water is set to a predetermined high water temperature when the engine operation region is a partial load region, and a set temperature of cooling water is set to a predetermined temperature when the engine operation region is a high load region. In a hybrid vehicle having a cooling water temperature changing means for reducing the cooling water temperature, when the engine operation region is switched from the partial load region to the high load region, the cooling water temperature is maintained until the cooling water temperature reaches a predetermined low water temperature. The shortage of the internal combustion engine torque with respect to the required load caused by the high is compensated by the motor torque of the motor generator. As a result, when the engine operating region is switched from the partial load region to the high load region and the cooling water temperature does not fall to the predetermined low water temperature, the shortage of the internal combustion engine torque with respect to the required load is compensated by the motor torque of the motor generator. Further, it is possible to prevent the deterioration of the operation performance immediately after the engine operation region is switched from the partial load region to the high load region.

  (2) Specifically, the hybrid vehicle described in (1) includes a cooling water temperature detecting unit that detects the cooling water temperature, and the motor torque that compensates for the shortage of the internal combustion engine torque with respect to the required load is detected by the cooling water temperature. The temperature is set so as to decrease as the temperature difference between the cooling water temperature detected by the means and the predetermined low water temperature decreases.

  (3) The hybrid vehicle described in the above (1) or (2) is generated from the drive source until the engine operation region is switched from the partial load region to the high load region and the cooling water temperature becomes a predetermined low water temperature. The driving force is set to be substantially constant. As a result, even if the shortage of the internal combustion engine torque is compensated for by the motor torque of the motor generator, the driver does not feel uncomfortable and comfortable driving performance can be realized.

  (4) The hybrid vehicle according to any one of (1) to (3) specifically includes means for detecting the remaining battery level of the battery that drives the motor generator, and the cooling water temperature changing means includes: When the remaining battery level is equal to or less than a predetermined amount set in advance, the engine operation region is set to a predetermined low temperature in the partial load region, and the engine operation region is set to a predetermined low temperature in the same manner as the coolant temperature in the high load region. Change to water temperature.

  (5) The hybrid vehicle according to any one of (1) to (4) specifically includes a driver intention determination unit that determines a driver's driving intention, and the driver is driving with low fuel consumption. When the engine operation region is desired, the set temperature of the cooling water in the partial load region is changed to a predetermined low water temperature in the same manner as the set temperature of the cooling water in the engine operation region is the high load region.

  (6) The hybrid vehicle according to any one of (1) to (5), specifically, the internal combustion engine torque corresponding to the required load from the current target throttle opening and a predetermined low water temperature of the cooling water. And the current internal combustion engine torque is calculated from the rotational load of the internal combustion engine and the current coolant temperature, and the motor torque is calculated by the motor generator according to the difference between the internal combustion engine torque corresponding to the required load and the current internal combustion engine torque. Is generated.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows typically schematic structure of the hybrid vehicle to which this invention is applied. A map used to calculate the set temperature of cooling water determined according to the required load and engine speed. Timing chart when the operation area is switched from the partial load area to the high load area. The flowchart which shows the flow of control of the hybrid vehicle which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Motor generator for electric power generation 3 ... Clutch 4 ... Motor generator for driving | running | working 5 ... Battery 8 ... Automatic transmission 11 ... Drive wheel

Claims (6)

When the engine operating region is a partial load region, the set temperature of the cooling water is a predetermined high water temperature, and when the engine operating region is a high load region, the set temperature of the cooling water is a predetermined low water temperature. A hybrid vehicle having cooling water temperature changing means for
When the engine operating region is switched from the partial load region to the high load region, the shortage of the internal combustion engine torque with respect to the required load caused by the high cooling water temperature is the motor generator until the cooling water temperature reaches the predetermined low water temperature. A hybrid vehicle that is supplemented with a motor torque.   The motor torque that has a cooling water temperature detecting means for detecting the cooling water temperature and compensates for the shortage of the internal combustion engine torque with respect to the required load has a small temperature difference between the cooling water temperature detected by the cooling water temperature detecting means and a predetermined low water temperature. The hybrid vehicle according to claim 1, wherein the hybrid vehicle is set to become smaller as the vehicle travels.   The driving force generated from the driving source is set to be substantially constant until the engine operation region is switched from the partial load region to the high load region and the cooling water temperature becomes a predetermined low water temperature. The hybrid vehicle according to 1 or 2.   The cooling water temperature changing means has a means for detecting the remaining battery level of the battery that drives the motor generator, and the cooling water temperature changing means is configured such that when the remaining battery level is equal to or lower than a predetermined amount, The hybrid vehicle according to any one of claims 1 to 3, wherein the set temperature of the engine is changed to a predetermined low water temperature in the same manner as the set temperature of the cooling water when the engine operating region is in a high load region.   When there is a driver intention determination means for determining the driver's driving intention, and the driver desires a fuel-efficient driving, the engine operating area is set to the set temperature of the cooling water in the partial load area, and the engine operating area is The hybrid vehicle according to claim 1, wherein the hybrid vehicle is changed to a predetermined low water temperature in the same manner as the set temperature of the cooling water in the load region. The internal combustion engine torque corresponding to the required load is calculated from the current target throttle opening and the predetermined low water temperature of the cooling water,
The current internal combustion engine torque is calculated from the internal combustion engine rotational load and the current coolant temperature,
6. The hybrid vehicle according to claim 1, wherein the motor generator generates motor torque in accordance with a difference between the internal combustion engine torque corresponding to the required load and the current internal combustion engine torque.

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