JP5223903B2 - Idle control device for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid uncomfortable feeling caused by an abrupt change of the number of idling revolutions while suppressing the heat generation of a second clutch between power sources and drive wheels. <P>SOLUTION: An engine and a motor/generator as the power sources are connected to each other via a first clutch, and the power sources and the drive wheels are connected to each other via the second clutch in an automatic transmission. When the automatic transmission is switched to a D-range from an N-range during an idling operation at which the engine is operated, the number of target idling revolutions is decreased, however, the number is gradually decreased at a prescribed change rate since the uncomfortable feeling caused by the abrupt change is avoided. When there is a requirement of a drive force during the decrease, the number of the target idling revolutions is quickly decreased by setting the change rate large, and the heat generation of the second clutch is suppressed. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to control during idling of a hybrid vehicle that includes an engine and a motor as power sources and in which a clutch is provided between the power source and drive wheels.

  As a vehicle drive system, a motor (generally a motor / generator) is positioned between the engine and the transmission, and the motor and the engine are connected via a first clutch in a form that can be engaged and released, Patent Document 1 discloses a hybrid vehicle in which a second clutch serving as a starting clutch is interposed between a motor and driving wheels. In this configuration, smooth start is realized by bringing the second clutch into the slip engagement state in accordance with the required driving force based on the accelerator pedal operation.

  Patent Document 1 discloses that in such a hybrid vehicle, idle speed control is performed using motor speed control during idle operation in which the engine is operating.

JP 2010-143418 A

  When the idle speed control of the power source including the engine and the motor is performed using the motor speed control as described above, for example, the target idle speed is set by switching the transmission from the N range to the D range. When the vehicle speed decreases, the rotational speed changes with an excessively high responsiveness as it is, and there is a concern that the driver feels uncomfortable like the so-called idling.

  On the other hand, if the rate of decrease in the target idle speed reduction is slowly limited, it takes some time to completely shift to the low target idle speed, and during this time, a request for driving force (typically by the driver) When the accelerator pedal is depressed, there is a concern that the clutch (the second clutch in Patent Document 1) with the drive wheel in the slip engagement state generates excessive heat.

  The idle control device of the present invention includes an engine and a motor that are connected to each other directly or via various mechanisms as a power source, and a clutch is interposed between the power source and the drive wheel, It is premised on a hybrid vehicle that starts the vehicle by variably controlling the transmission torque capacity of the clutch according to the driving force requirement of the vehicle. In the present invention, the engine is operating and the motor is in the idling operation in which the rotational speed is controlled, and the second target idle is relatively low from the relatively high first target idle rotational speed. When the speed is switched to the rotational speed, the speed of decrease of the target rotational speed that changes from the first target idle rotational speed to the second target idle rotational speed is limited to the first decreasing speed. Further, when there is a driving force request before the target rotation speed converges to the second idle rotation speed, the second target idle rotation is performed at a second reduction speed larger than the first reduction speed. It is configured to change to a number.

  That is, in an idle operation state in which the engine is operating and the motor is controlled in rotational speed, for example, when the range of the automatic transmission is switched from the non-traveling range to the traveling range, the first target idling rotational speed is lower. However, the speed of reduction of the target rotational speed at that time is limited to the first speed of reduction, so that the target rotational speed and thus the actual idle rotational speed decreases relatively slowly. Then, if there is a request for driving force (typically, the driver depresses the accelerator pedal) while the idling engine speed slowly decreases in this way, the clutch transmission torque increases, but the target engine speed is increased. The lowering speed becomes a larger second lowering speed, and the target rotational speed, and hence the actual idle rotational speed, quickly decreases to the second target idle rotational speed. Therefore, the rotational speed difference before and after the clutch is reduced, and heat generation is suppressed.

  According to the present invention, when the target idle speed is changed by changing the range of the transmission or the like, the actual rotational speed of the engine and the motor does not decrease excessively, and the driver does not feel uncomfortable. At the same time, it is possible to suppress heat generation of the clutch when there is a request for driving force.

BRIEF DESCRIPTION OF THE DRAWINGS Structure explanatory drawing which shows one Example of the power train of the hybrid vehicle to which this invention is applied. Structure explanatory drawing which shows the modification of the power train of the hybrid vehicle to which this invention is applied. Structure explanatory drawing which shows the further modification of the power train of the hybrid vehicle to which this invention is applied. The block diagram which shows the control system of this power train. The flowchart which shows the flow of the process which determines the change rate of target rotation speed. The block diagram which shows the principal part of control of target idle speed. The block diagram which shows the calculation of the change rate at the time of clutch protection. The time chart which shows an example of the operation | movement by this invention.

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

  First, a basic configuration of a hybrid vehicle to which the present invention is applied will be described. FIG. 1 shows a power train of a hybrid vehicle having a front engine / rear wheel drive (FR) type configuration as one embodiment of the present invention, wherein 1 is an engine and 2 is a drive wheel (rear wheel). The present invention is not limited to this FR format, and can be applied to other formats such as FF format or RR format.

  In the power train of the hybrid vehicle shown in FIG. 1, an automatic transmission 3 is arranged in tandem at the rear of the engine 1 in the vehicle front-rear direction in the same manner as a normal rear wheel drive vehicle, and the engine 1 (crankshaft 1a) A motor / generator 5 is integrally provided on the shaft 4 that transmits the rotation to the input shaft 3 a of the automatic transmission 3.

  The motor / generator 5 is composed of a synchronous motor using a permanent magnet as a rotor, and acts as a motor (so-called “powering”) and also acts as a generator (so-called “regeneration”). As described above, it is located between the engine 1 and the automatic transmission 3. More specifically, a first clutch 6 is inserted between the motor / generator 5 and the engine 1, more specifically between the shaft 4 and the engine crankshaft 1 a, and the first clutch 6 is connected to the engine 1. The motor / generator 5 is detachably coupled.

  Here, the first clutch 6 has a configuration in which the transmission torque capacity can be continuously changed. For example, the first clutch 6 is normally closed so that the transmission torque capacity can be changed by continuously controlling the clutch hydraulic pressure with a proportional solenoid valve or the like. It consists of a dry type single plate clutch or a wet multi-plate clutch.

  Further, a second clutch 7 is interposed between the motor / generator 5 and the drive wheel 2, more specifically, between the shaft 4 and the transmission input shaft 3a. The second clutch 7 is connected to the motor. / The generator 5 and the automatic transmission 3 are detachably coupled.

  Similarly to the first clutch 6, the second clutch 7 is configured so that the transmission torque capacity can be continuously changed. For example, the transmission torque capacity can be changed by continuously controlling the clutch hydraulic pressure with a proportional solenoid valve. It consists of possible wet multi-plate clutch or dry single-plate clutch.

  The automatic transmission 3 selectively engages or releases a plurality of friction elements (such as clutches and brakes), and thus, by changing the engagement / release of these friction elements, the forward speed, the reverse speed, the reverse speed, etc. It is realized. That is, the automatic transmission 3 shifts the rotation input from the input shaft 3a at a gear ratio corresponding to the selected shift speed, and outputs it to the output shaft 3b. This output rotation is distributed and transmitted to the left and right drive wheels (rear wheels) 2 via the differential gear device 8. The automatic transmission 3 is not limited to the stepped type as described above, and may be a continuously variable transmission. The automatic transmission 3 has a P (parking) range and N (neutral) range which are non-traveling ranges, and a D (drive) range and R which are traveling ranges as ranges selected by the driver via a select lever or the like. (Reverse) range at least.

  In the power train described above, an electric vehicle traveling mode (EV mode) that travels using only the power of the motor / generator 5 as a power source, and a hybrid traveling mode (HEV) that travels while the engine 1 is included in the power source together with the motor / generator 5. Mode). For example, the EV mode is required at low loads and low vehicle speeds, including when starting from a stopped state. In this EV mode, the power from the engine 1 is unnecessary, so that the first clutch is stopped. 6 is released and the second clutch 7 is engaged, and the automatic transmission 3 is set in the power transmission state. In this state, the vehicle is driven only by the motor / generator 5.

  Further, for example, the HEV mode is required during high-speed traveling or heavy load traveling. In this HEV mode, the first clutch 6 and the second clutch 7 are both engaged, and the automatic transmission 3 is brought into a power transmission state. In this state, both the output rotation from the engine 1 and the output rotation from the motor / generator 5 are input to the transmission input shaft 3a, and hybrid traveling by both is performed.

  The motor / generator 5 can recover and recover braking energy when the vehicle is decelerated, and can recover surplus energy of the engine 1 as electric power in the HEV mode.

  When transitioning from the EV mode to the HEV mode, the first clutch 6 is engaged and the engine is started using the torque of the motor / generator 5. At this time, the mode can be smoothly switched by variably controlling the transmission torque capacity of the first clutch 6 and performing the slip engagement.

  Further, the second clutch 7 functions as a so-called start clutch, and by variably controlling the transmission torque capacity and starting the slip engagement when starting the vehicle, it absorbs torque fluctuations smoothly even in a power train that does not include a torque converter. The start is possible.

  In FIG. 1, the second clutch 7 located between the motor / generator 5 and the drive wheels 2 is interposed between the motor / generator 5 and the automatic transmission 3, but the embodiment shown in FIG. As described above, the second clutch 7 may be interposed between the automatic transmission 3 and the differential gear device 8.

  In the embodiment shown in FIGS. 1 and 2, a dedicated second clutch 7 is provided at the front or rear of the automatic transmission 3, but instead the second clutch 7 is shown in FIG. As shown, an existing forward shift speed selection friction element or reverse shift speed selection friction element in the automatic transmission 3 may be used. In this case, the second clutch 7 is not necessarily one friction element, and an appropriate friction element corresponding to the gear position can be the second clutch 7.

  FIG. 4 shows a control system in the power train of the hybrid vehicle configured as shown in FIGS.

  The control system includes an integrated controller 20 that integrally controls the operating point of the power train. The operating points of this power train are the target engine torque tTe, the target motor / generator torque tTm (or the target motor / generator rotation speed tNm), the target transmission torque capacity tTc1 of the first clutch 6, and the target of the second clutch 7. And transmission torque capacity tTc2.

  Further, this control system includes at least an engine rotation sensor 11 that detects an engine rotation speed Ne, a motor / generator rotation sensor 12 that detects a motor / generator rotation speed Nm, and an input rotation that detects a transmission input rotation speed Ni. A sensor 13, an output rotation sensor 14 for detecting a transmission output speed No, an accelerator opening sensor 15 for detecting an accelerator pedal depression amount (accelerator opening APO) indicating a required load state of the engine 1, and a motor / generator And a storage state sensor 16 that detects the storage state SOC of the battery 9 that stores the power for 5, and these detection signals are input to the integrated controller 20 to determine the operating point. Has been.

  The engine rotation sensor 11, the motor / generator rotation sensor 12, the input rotation sensor 13, and the output rotation sensor 14 are arranged, for example, as shown in FIGS.

  The integrated controller 20 determines the vehicle driving force requested by the driver from the accelerator opening APO, the battery storage state SOC, and the transmission output speed No (vehicle speed VSP) in the input information. And a target engine torque tTe, target motor / generator torque tTm (or target motor / generator rotation speed tNm), target first clutch transmission torque capacity tTc1, and A target second clutch transmission torque capacity tTc2 is calculated.

  The target engine torque tTe is supplied to the engine controller 21, and the engine controller 21 controls the engine 1 so that the actual engine torque Te becomes the target engine torque tTe. For example, the engine 1 is a gasoline engine, and the engine torque Te is controlled via the throttle valve.

  On the other hand, the target motor / generator torque tTm (or the target motor / generator rotation speed tNm) is supplied to the motor / generator controller 22, and the motor / generator controller 22 receives the torque Tm (or rotation speed Nm) of the motor / generator 5. The motor / generator 5 is controlled via the inverter 10 so that becomes the target motor / generator torque tTm (or the target motor / generator rotational speed tNm).

  Further, the integrated controller 20 applies solenoid currents respectively corresponding to the target first clutch transmission torque capacity tTc1 and the target second clutch transmission torque capacity tTc2 to the engagement control solenoid valves (not shown) of the first clutch 6 and the second clutch 7. ) So that the transmission torque capacity Tc1 of the first clutch 6 matches the target transmission torque capacity tTc1, and the transmission torque capacity Tc2 of the second clutch 7 matches the target second clutch transmission torque capacity tTc2. In addition, the engaged state of the first clutch 6 and the second clutch 7 is individually controlled.

  The integrated controller 20 is also connected to an AT controller 31 that controls the automatic transmission 3. The AT controller 31 determines the optimum gear position from the range position selected by the above-mentioned select lever or the like, the vehicle speed VSP (transmission output rotational speed No), and the accelerator opening APO, and the automatic transmission 3 Shift control is performed by changing the friction elements. Information indicating various states of the automatic transmission 3 is input to the integrated controller 20. As shown in FIG. 3, when the second clutch 7 is substantially constituted by the friction element of the automatic transmission 3, the second clutch 7 is actually controlled via the AT controller 31.

  The flowchart of FIG. 5 shows the flow of processing for determining the target idle speed and the rate of change (rate of change) that are the main part of the present invention. This process is repeatedly executed during operation, for example. Here, the state in which the drive wheel side is unloaded is referred to as idle, and is usually a vehicle stop state.

  In step 1, it is determined whether or not the HEV mode in which the engine 1 and the motor / generator 5 are coupled by the first clutch 6. Since the EV mode in which the first clutch 6 is released and the engine 1 is stopped is not the subject of the present invention, this routine is terminated.

  While the vehicle is stopped, the EV mode is basically in which the first clutch 6 is disengaged and the engine 1 is stopped. However, the power request, the state of charge SOC of the battery 9, the engine 1 immediately after the start of the cold machine, Depending on the warm-up state of the vehicle, the HEV mode with the operation of the engine 1 can be performed even when the vehicle is stopped. During idle operation in which the engine 1 is operating, basically, idle speed control is performed by controlling the rotational speed of the motor / generator 5 (here, the engine rotational speed Ne and the motor / generator rotational speed Nm are equal to each other). ) Is realized. Exceptionally, when the storage state SOC of the battery 9 is extremely small, the motor / generator 5 is controlled by torque, and the target idle speed is set by the idle speed control mechanism of the engine 1 itself (in other words, the engine controller 21). Although control to maintain is performed, the present invention is not intended for such idle speed control on the engine 1 side.

  In step 2, it is determined whether or not the range position of the automatic transmission 3 is the N range or the P range, which is a non-traveling range. If the non-traveling range is the N range or the P range, the process proceeds to step 3 where a relatively high first target idle speed tN1 is selected, and in step 4, the change rate of the target speed change is set to “normal time”. Change rate ". Although the first target idle speed tN1 can be said to be the target speed of the engine 1, it is the target speed tNm of the motor / generator 5 in terms of control. Further, the above normal rate of change prescribes the rate of change of the target rotational speed tNm of the motor / generator 5 mainly so that the change of the engine rotational speed Ne perceived by the driver is not excessively abrupt. It is.

  On the other hand, when the range position of the automatic transmission 3 is a travel range, for example, the D range or the R range, the process proceeds to step 5 to select a relatively low second target idle speed tN2, and then proceeds to step 6. The reason why the target idle speed is high in the non-traveling range as described above is to promote warm-up of the engine 1, avoid engine stall, and the like. This is mainly for ensuring the durability of the second clutch 7. During the idle operation in the HEV mode, the target torque tTe on the engine 1 side that is torque-controlled is basically larger than the torque required for the independent operation of the engine 1 alone by the necessary power generation requirement. Thus, the energy is absorbed by the regeneration of the motor / generator 5 and is balanced at the target idle speed.

  In step 6, it is determined whether or not the required driving force value at that time (for example, calculated based on the accelerator opening APO) is equal to or less than a threshold value. In step 7, it is determined whether the vehicle speed VSP is equal to or higher than a threshold value. If the required driving force value is equal to or less than the threshold value or the vehicle speed VSP is equal to or greater than the threshold value, the process proceeds to step 4 and the target change rate is also set to “normal change rate”. On the other hand, if the required driving force value is greater than the threshold value and the vehicle speed VSP is less than the threshold value, the process proceeds to step 8 where the change rate of the target rotational speed change is greater than the “normal change rate”. Rate ". This rate of change during clutch protection gives priority to protection of the second clutch 7 over prevention of uncomfortable feeling. Here, “the rate of change or rate of change” is “large” means that the change is abrupt, whether it is an increase or a decrease. In other words, it is a comparison of absolute values. Since the change rate during clutch protection can be selected only when the target rotational speed tNm is switched from the first target idle rotational speed tN1 to the relatively low second target idle rotational speed tN2, in practice, This is a reduction rate or reduction rate of the target rotational speed tNm, and is set to be abrupt than the normal reduction rate or reduction rate. The rate of change during clutch protection will be further described later with reference to FIG.

  FIG. 6 shows the processing shown in the flowchart of FIG. 5 as a functional block diagram. The changeover switch of the block 41 uses the first target based on the range signal (D range, R range) of the automatic transmission 3. Switching between the idle speed tN1 and the second target idle speed tN2 is performed. Then, the target rotational speed tNm of the motor / generator 5 is sequentially output through the change rate limiting process shown as the block 42. The change rate limiting process 42 is performed by the changeover switch of the block 43 according to two conditions, ie, whether the required driving force value is less than the threshold value or the vehicle speed is more than the threshold value. Is selected as a change rate, and the change in the target rotational speed tNm is limited using this change rate.

  FIG. 7 is a functional block diagram showing the process for determining the clutch protection change rate. In this embodiment, the rate of change at the time of clutch protection is obtained based on the two parameters, and a larger value is selected as the final rate of change at the time of clutch protection. That is, in the first change rate calculation unit shown as block 51, the heat generation amount of the second clutch 7 is input, and the first clutch protection change rate corresponding to this heat generation amount according to the relationship previously provided as a table or the like. Ask for. Note that the amount of heat generated by the second clutch 7 is separately calculated from, for example, the rotational speed difference of the second clutch 7 and the target driving force, but may be estimated from other parameters or directly detected by some means. Also good. Basically, the greater the amount of heat generated, the greater the first clutch protection change rate. Further, in the second change rate calculation unit shown as block 52, the driving force request value is input, and a second clutch protection change rate corresponding to this driving force request value is obtained in accordance with a relationship previously provided as a table or the like. . Basically, the larger the driving force requirement value, the larger the second clutch protection change rate. Then, in the comparison unit of block 53, any larger value is output as the final change rate during clutch protection.

  FIG. 8 is an example of a time chart showing changes in the target idle speed when the automatic transmission 3 is switched from a non-traveling range (for example, N range) to a traveling range (for example, D range) during idling with engine operation. Is shown. In this example, the vehicle is stopped during the period shown, and the accelerator opening APO is initially 0, that is, the fully closed position. As described above, by controlling the rotational speed of the motor / generator 5, the rotational speed of the power source composed of the engine 1 and the motor / generator 5 can be said to be the target idle rotational speed (the target rotational speed tNe of the engine 1). In the configuration example 3, it is also the transmission input rotational speed Ni, but here it is typically controlled to the target rotational speed tNm of the motor / generator 5).

  In such an idle operation state, as shown as a “select signal”, the automatic transmission 3 is initially in the N range (or P range), and therefore the target speed tNm is a relatively high first target. It is at idle speed tN1.

  When the state is switched to the D range (or R range) at time t1, the target idle speed is switched to the relatively low second target idle speed tN2, but as described above, the motor / generator 5 The target rotational speed tNm used in the rotational speed control does not change stepwise, but changes relatively slowly along the normal rate of change given in step 5 of FIG. Therefore, the actual rotational speed of the power source including the engine 1 is also slowly decreased, and the driver does not feel uncomfortable. Note that the characteristic of the normal change rate is set, for example, to approximate the characteristic of a traditional vehicle driven by an engine alone that is not a hybrid vehicle.

  Note that when the automatic transmission 3 is thus switched to the D range, the automatic transmission 3 is controlled to be shifted to a predetermined shift speed, for example, the first speed. At the same time, the second clutch 7 changes from the released state to the slip engaged state.

  Here, while the target rotational speed tNm is decreasing along the above normal change rate, at time t2, for example, when a driving force exceeding a threshold value is requested due to depression of the driver's accelerator pedal, the driving force The flag is turned ON, and the change rate is changed to the clutch protection change rate described above. Accordingly, the target rotational speed tNm quickly decreases to the second target idle rotational speed tN2 as indicated by the solid line.

  The transmission torque capacity Tc2 of the second clutch 7 in the slip engagement state is given along the target driving force (required driving force), and the difference in rotational speed before and after that is determined by the rotational speed Nm of the motor / generator 5. If the transmission torque increases due to an increase in the required driving force with a large rotational speed difference, the amount of heat generated by the second clutch 7 becomes large, which is not preferable. In the above-described embodiment, when the driving force exceeding the threshold is requested, the target rotational speed tNm is rapidly reduced by the rate of change at the time of clutch protection, so the rotational speed difference is reduced and the second clutch 7 generates heat. It is suppressed. In the example of this time chart, the vehicle remains stopped by the driver's brake operation even after time t2.

  Thereafter, when the range position of the automatic transmission 3 is switched again to the non-traveling range (N range or P range) at time t3, the normal change rate in step 4 described above (strictly, the sign is reversed) Is selected, and the target rotational speed tNm increases along the normal change rate. Thereby, the feeling of the engine 1 blowing up is suppressed. As is apparent from the flowchart of FIG. 5, even if the driving force is requested in the middle of the change of the target rotation speed tNm after the time t3, the change rate is not changed.

  As described above, in the above embodiment, when there is no request for driving force, the decrease in the target rotational speed tNm is made relatively slow, and when there is a request for driving force, the target rotational speed tNm is quickly set. Therefore, both the mitigation of the uncomfortable feeling felt by the driver and the suppression of heat generation of the second clutch 7 can be achieved. In particular, since the rate of change at the time of clutch protection is set in consideration of the amount of heat generated by the second clutch 7 and the required driving force value, the second clutch 7 can be protected more reliably and the change in the rotational speed is the minimum necessary. Will be made. In the above time chart, the vehicle is described as being stopped. However, when the vehicle speed is equal to or higher than the threshold as shown in step 7 of FIG. 5, the control algorithm is configured not to change the clutch protection change rate. As a result, an unnecessary limitation on the rotational speed change is reliably avoided.

  In the above-described embodiment, the change of the target idle speed accompanying the switching of the range position of the automatic transmission 3 has been described. However, the present invention is not limited to this, and is accompanied by, for example, whether there is a power generation request or an auxiliary machine load. The same can be applied to the change of the target idle speed.

  In the above embodiment, the engine 1 and the motor / generator 5 are connected so as to rotate at a constant speed via the first clutch 6. However, even if the both are always connected directly, The present invention can be similarly applied even to configurations that are connected to each other via a reduction gear mechanism or the like.

DESCRIPTION OF SYMBOLS 1 ... Engine 3 ... Automatic transmission 5 ... Motor / generator 6 ... 1st clutch 7 ... 2nd clutch 9 ... Battery 10 ... Inverter 20 ... Integrated controller 21 ... Engine 31 ... AT controller

Claims (5)

The engine and motor are connected to each other as a power source, and a clutch is interposed between the power source and the drive wheels, and the transmission torque capacity of the clutch is variably controlled according to the driving force requirement of the vehicle. In a hybrid vehicle that starts the vehicle by
The engine is in operation and the motor is in an idling operation in which the rotation speed is controlled, and is switched from a relatively high first target idle rotation speed to a relatively low second target idle rotation speed. When the target rotational speed changing from the first target idle rotational speed to the second target idle rotational speed is limited to the first decreasing speed,
If there is a driving force request before the target rotational speed converges to the second idle rotational speed, the second target idle rotational speed is reached at a second lower speed than the first lower speed. An idle control device for a hybrid vehicle, characterized by being changed.   The idle control device for a hybrid vehicle according to claim 1, wherein the second decreasing speed is set based on a heat generation amount of the clutch.   2. The idle control device for a hybrid vehicle according to claim 1, wherein the second reduction speed is set based on a requested magnitude of the driving force. 3.   The idle control device for a hybrid vehicle according to any one of claims 1 to 3, wherein when the vehicle speed is equal to or higher than a predetermined value, the second reduction speed is not changed.   An automatic transmission is provided between the power source and the drive wheel, and the first target idle speed is set in the travel range, and the second target idle speed is set in the non-travel range. An idle control device for a hybrid vehicle according to any one of the above.

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