JP2005083493A - Controller of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve more a fuel consumption when a modulated cylinder engine is loaded to perform a neutral control. <P>SOLUTION: An ECT<SB>-</SB>ECU 1020 performs the neutral control for releasing an input clutch C1 when a state of a vehicle satisfies predetermined conditions and stops at a forward traveling position. The engine ECU 1010 performs a variable cylinder controller for changing the number of operating cylinders based on an operating state of the engine 100. The ECT<SB>-</SB>ECU 1020 includes a circuit for sensing the number of the operating cylinders of the engine 100 controlled by the engine ECU 1010, and a circuit for reducing a target hydraulic pressure of the input clutch C1 when a sensing result by a sensing circuit shows that the engine 100 is operated in the partial cylinder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle control device, and more particularly to a vehicle control device equipped with an automatic transmission that performs neutral control.

  An automatic transmission mounted on a vehicle is configured to include a transmission mechanism that is connected to an engine via a torque converter or the like and has a plurality of power transmission paths. For example, an automatic transmission is automatically set based on an accelerator opening and a vehicle speed. Thus, the power transmission path is switched, that is, the gear ratio (travel speed stage) is automatically switched. Generally, a vehicle having an automatic transmission is provided with a shift lever operated by a driver, and a shift position (for example, a reverse travel position, a neutral position, a forward travel position) is set based on the shift lever operation. The automatic shift control is performed in the shift position set in this way (usually, in the forward travel position).

  In a vehicle having such an automatic transmission, in a state where the forward traveling position is set and the vehicle is stopped, the driving force from the idling engine is transmitted to the transmission via the torque converter, which is the wheel. Therefore, a so-called creep phenomenon occurs. Creep phenomenon is very useful under certain conditions, such as smooth starting from a stop on an uphill road, but it is an unnecessary phenomenon when you want to keep the vehicle stopped, and it activates the vehicle brake To suppress the creep force. That is, the creep force from the engine is suppressed by the brake, and there is a problem that the fuel consumption of the engine is reduced accordingly.

  For this reason, in the forward travel position, when the brake pedal is depressed and the brake is activated, and the accelerator is almost fully closed and the vehicle is stopped, the transmission remains in the forward travel position to neutral. It has been proposed to improve fuel efficiency in a near neutral state.

  An input clutch (also referred to as a forward clutch or a forward clutch) in an automatic transmission is changed from an engaged state to a released state, and fuel efficiency is improved by realizing such a neutral state. Hereinafter, such control is referred to as neutral control.

  On the other hand, as a technology for improving fuel efficiency, a variable cylinder engine that improves the fuel consumption rate of the entire engine by stopping the operation of some cylinders and reducing the number of operating cylinders when the engine is partially loaded Is generally known. In a normal engine, in the partial load operation, the intake passage is throttled by the throttle valve in order to reduce the intake air amount of the entire engine, and the negative pressure of the intake pipe downstream of the throttle valve increases. For this reason, the pumping loss at the time of sucking air into the engine combustion chamber increases. On the other hand, in a variable cylinder engine, some cylinders are deactivated during low load operation, and only the remaining cylinders are operated. In the same load state, it is necessary to increase the intake amount according to the decrease in the number of active cylinders and increase the output per operating cylinder when the cylinders are deactivated, compared to when all cylinders are operating normally. Therefore, the variable cylinder engine is operated in a state where the throttle of the intake passage is smaller and the negative pressure of the intake pipe is smaller than when all cylinders are operated in the same load state when the cylinder is deactivated. For this reason, the pumping loss at the time of partial load is reduced, and the fuel consumption rate as the whole engine is improved.

  That is, in such a variable cylinder engine, the intake and exhaust valves of the engine always open and close regardless of whether fuel is supplied or not. In general, the greater the number of operating cylinders, the less the vibration, The better the performance and the smaller the number of operating cylinders, the larger the opening of the idle speed control valve, so that the pumping loss is minimized and the fuel efficiency is improved.

  Japanese Patent Laid-Open No. 9-158751 (Patent Document 1) discloses such an output control device for a variable cylinder engine. This output control device makes it possible to supply the minimum amount of fuel when the fuel supply is stopped and then restarted. This output control device is an output control device for an engine that is coupled to a transmission by engagement via a fluid during deceleration, and the operation of a predetermined cylinder when the vehicle is decelerated to a predetermined first running state. And the operation of at least a part of the cylinders that have stopped operating when the vehicle is further decelerated to enter the second traveling state is restarted, and the output after the restart is started from the predetermined target output from the vehicle side. The output is controlled by subtracting the input reverse driving force.

According to the output control device disclosed in Patent Document 1, when restarting the operation of a cylinder that has stopped operating, only the output obtained by subtracting the amount of the reverse driving force from the vehicle side from the target output can be given more than necessary. Is prevented from being supplied. In this output control device, drivability can also be improved by setting a higher target engine speed in the adjustment range of the number of operating cylinders and the intake air amount.
JP 9-158751 A

  However, Patent Document 1 does not refer to neutral control. Even if there is a disclosure of setting a high engine speed, a case where neutral control and variable cylinder control are combined, that is, all cylinders are disclosed. The output control device disclosed in Patent Document 1 cannot solve the following problems that occur when neutral control is executed, whether during operation or during partial cylinder operation.

  First, the mechanism by which the fuel efficiency improvement effect in the neutral control is manifested without being related to the variable cylinder control will be described.

  Differences between when neutral control is performed and when neutral control is not performed will be described based on the capacity coefficient of the torque converter.

  FIG. 5 is a general view showing the characteristics of the capacity coefficient of the torque converter, and shows the capacity coefficient of the torque converter with respect to the speed ratio e (= turbine speed NT / engine speed NE) from 0 to 1. Yes.

  Immediately before the neutral control is executed, since the vehicle is stopped at the forward travel position, the speed ratio e = 0 and the capacity coefficient C = C (1). When the neutral control is executed, the input clutch C1 is released while the vehicle is stopped at the forward travel position, so that the speed ratio e is e = 0.9, for example, the capacity coefficient C = C (2) (C (1)> C (2)> 0).

If the engine speed NE is constant, the engine torque TE = torque converter pump side torque TP = C × NE ² . Therefore, the neutral control is executed with the engine speed NE being constant, the input clutch C1 is released, the engine torque is transmitted by the torque converter, the speed ratio e is increased, and the capacity coefficient C is C (1 ) To C (2).

Thus, the torque required for the engine when the neutral control is being executed is expressed by C (2) × NE ² , which is the torque required for the engine when the neutral control is not being executed. Since it is smaller than a certain C (1) × NE ² , the fuel efficiency improvement effect is exhibited. In practice, the engagement pressure of the input clutch C1 is feedback-controlled so that the speed ratio e becomes the target speed ratio.

  The case where neutral control is executed when the number of operating cylinders of the engine is different will be described on the premise of a mechanism for improving fuel consumption in the neutral control generated in this way. In the following description, a six-cylinder engine is taken as an example, and it is assumed that fuel is supplied to only three cylinders and ignited when a partial cylinder is operating.

  FIG. 6 illustrates a case where the target engagement pressure (target hydraulic pressure) of the input clutch C1 is the same hydraulic pressure even when the number of operating cylinders is different (6 cylinders, 3 cylinders) when performing neutral control. Since the torque ratio (= turbine torque TT / engine torque TE) is uniquely determined by the speed ratio e, when the 6-cylinder operation with a large engine torque TE is in operation, the turbine torque TT also increases and the ECT_ECU releases the input clutch C1 ( The control is performed so that the target speed ratio e is obtained. When the three-cylinder operation with a small engine torque TE is performed, the turbine torque TT is small, and the ECT_ECU is operated so as to engage (do not slide) the input clutch C1, and control is performed so as to achieve the target speed ratio e. .

  Therefore, as shown in FIG. 6, when the target engagement pressure (target hydraulic pressure) of the input clutch C1 is the same (when the 3-cylinder is operated, the target hydraulic pressure of the input clutch is high as when the 6-cylinder is operated). ) When three cylinders are operating, the time from the start of neutral control until the speed ratio e becomes a constant region (a region where the target speed ratio is stable) and a fuel efficiency improvement effect is manifested. It will be late compared.

  That is, when the three-cylinder operation with a small engine torque TE is performed, the turbine torque TT is small, and the ECT_ECU tends to operate to engage (do not slide) the input clutch C1, and the target hydraulic pressure of the input clutch C1 remains high. Then, in the feedback control executed so as to reach the target speed ratio, the settling time becomes long. Also, as shown in FIG. 6, when the three cylinders are operated, the input clutch C1 is controlled so as to be changed from the engaged state to the disengagement side (the disengagement side of the input clutch C1 that satisfies the target speed ratio e). There is a case where the input clutch C1 is suddenly released after the control is executed, and a release shock of the input clutch C1 may occur.

  As described above, at the start of the neutral control, the target engagement pressure (target hydraulic pressure) of the input clutch C1 is set to the same hydraulic pressure as before, when all cylinders are operated and when partial cylinders are operated. If set, the expression of the fuel efficiency improvement effect of the neutral control at the time of partial cylinder operation will be delayed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to realize good fuel efficiency improvement characteristics when a variable cylinder engine is mounted and neutral control is executed. It is to provide a control device for a vehicle.

  A vehicle control device according to a first aspect of the present invention is based on a neutral control device that releases an input clutch when the vehicle state stops in a forward traveling position while satisfying a predetermined condition, and an engine operating state. A vehicle equipped with a variable cylinder control device that changes the number of operating cylinders is controlled. The control device includes a detection means for detecting the number of operating cylinders of the engine controlled by the variable cylinder control device, and a target hydraulic pressure of the input clutch in the neutral control based on the number of operating cylinders of the engine detected by the detection means. And changing means for changing.

  According to the first invention, when the partial cylinder is operated by the variable cylinder control device (for example, when 3 cylinders are operating in a 6-cylinder engine), when performing neutral control, all cylinders are operating. A lower hydraulic pressure than the case is set as the target hydraulic pressure of the input clutch. In this way, when the three cylinders are operating, the engine torque is small and the input clutch is on the engagement side. Therefore, by changing the target oil pressure (for example, lowering), the speed ratio is constant at a faster speed from the start of the neutral control. Can enter the area. If the target hydraulic pressure is the same as when all cylinders are operated, the time from the start of the neutral control to the entry into the region where the speed ratio is constant is prolonged, and the fuel efficiency improvement effect, which is the effect of the neutral control, is hardly exhibited. As a result, it is possible to provide a control device for a vehicle that can realize a favorable fuel efficiency improvement characteristic when a variable cylinder engine is mounted and neutral control is executed.

  In the vehicle control apparatus according to the second invention, in addition to the configuration of the first invention, when the changing means is determined to be operating the partial cylinder based on the number of operating cylinders detected by the detecting means. And means for reducing the target oil pressure as compared to when all cylinders are operating.

  According to the second invention, when the partial cylinder is in operation, the engine torque is small and the input clutch is on the engagement side. Therefore, by lowering the target hydraulic pressure, the region where the speed ratio is constant can be obtained earlier from the start of the neutral control. I can enter. Compared to the case where the target hydraulic pressure is the same as that for all cylinders and is not changed, the fuel efficiency improvement effect that is the effect of the neutral control can be easily realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  A power train of a vehicle including a control device according to an embodiment of the present invention will be described. The control device according to the present embodiment is realized by an ECU (Electronic Control Unit) 1000 shown in FIG. In this embodiment, the automatic transmission is described as an automatic transmission that includes a torque converter using a fluid coupling and has a gear-type transmission mechanism. The automatic transmission may be a continuously variable transmission (CVT) such as a belt type.

  With reference to FIG. 1, a power train of a vehicle including a control device according to the present embodiment will be described. The control apparatus according to the present embodiment is realized by ECT (Electronic Controlled Automatic Transmission) _ECU 1020 shown in FIG.

  As shown in FIG. 1, the power train of this vehicle includes an engine 100, a torque converter 200, an automatic transmission 300, and an ECU 1000.

  The output shaft of engine 100 is connected to the input shaft of torque converter 200. Engine 100 and torque converter 200 are connected by a rotating shaft. Therefore, output shaft speed NE (engine speed NE) of engine 100 detected by engine speed sensor 400 and input shaft speed (pump speed NP) of torque converter 200 are the same.

  The torque converter 200 includes a lock-up clutch 210 that directly connects the input shaft and the output shaft, a pump impeller 220 on the input shaft side, a turbine impeller 230 on the output shaft side, and a one-way clutch 250. It is comprised from the stator 240 which expresses an amplification function. Torque converter 200 and automatic transmission 300 are connected by a rotating shaft. The output shaft rotational speed NT (turbine rotational speed NT) of the torque converter 200 is detected by a turbine rotational speed sensor 410. The output shaft rotational speed NOUT of the automatic transmission 300 is detected by the output shaft rotational speed sensor 420.

  FIG. 2 shows an operation table of the automatic transmission 300. According to the operation table shown in FIG. 2, the clutch elements (C1 to C4 in the figure), the brake elements (B1 to B4), and the one-way clutch elements (F0 to F3) that are friction elements are in any gear. Shows what is combined and released. At the first speed used when the vehicle starts, the clutch element (C1) and the one-way clutch elements (F0, F3) are engaged. Among these clutch elements, the clutch element C1 is particularly referred to as an input clutch 310. The input clutch 310 is also referred to as a forward clutch or a forward clutch, and as shown in the operation table of FIG. 2, the vehicle moves forward except for the parking (P) position, the reverse traveling (R) position, and the neutral (N) position. Therefore, it is always used in the engaged state when the shift stage is configured.

  When the vehicle is in the forward travel (D) position and the vehicle state is stopped while satisfying a predetermined condition, control is performed to release the input clutch 310 to a predetermined slip state, which is close to the neutral state. This is called neutral control.

  The ECU 1000 that controls these power trains includes an engine ECU 1010 that controls the engine 100, an ECT (Electronic Controlled Automatic Transmission) _ECU 1020 that controls the automatic transmission 300, and a VSC (Vehicle Stability Control) _ECU 1030.

  The ECT_ECU 1010 receives a signal representing the turbine rotational speed NT from the turbine rotational speed sensor 410 and a signal representing the output shaft rotational speed NOUT from the output shaft rotational speed sensor 420. ECT_ECU 1010 receives from engine ECU 1010 a signal representing engine speed NE detected by engine speed sensor 400 and a signal representing the throttle opening detected by the throttle position sensor.

  These rotation speed sensors are provided to face the teeth of the rotation detection gear attached to the input shaft of torque converter 200, the output shaft of torque converter 200, and the output shaft of automatic transmission 300. These rotational speed sensors are sensors that can detect slight rotations of the input shaft of the torque converter 200, the output shaft of the torque converter 200, and the output shaft of the automatic transmission 300. This is a sensor using a magnetoresistive element.

  Further, ECT_ECU 1020 receives from VSC_ECU 1030 a signal representing vehicle acceleration detected by the G sensor and a signal representing brake pressure.

  The ECT_ECU 1020 outputs an engagement pressure command signal for the input clutch 310 and a solenoid control signal to the automatic transmission 300. The engagement pressure of the input clutch 310 is feedback controlled based on the target hydraulic pressure so that the speed ratio e of the torque converter 200 is constant. Engine ECU 1010 executes variable cylinder control for changing the number of operating cylinders of engine 100 in accordance with the operating state of engine 100. Here, engine 100 is a six-cylinder engine, and only three cylinders are operated when partial cylinders are operated.

  A control structure of a program executed in ECT_ECU 1020 of the control device according to the present embodiment will be described with reference to FIG.

  In step (hereinafter step is abbreviated as S) 100, ECT_ECU 1020 determines whether or not the vehicle is stopped. That is, it is determined whether the vehicle is in a stopped state and engine 100 is in an idle state. This determination is based on whether the engine 100 is in an idle state and the vehicle state is in a predetermined state (stopped state) based on a throttle opening signal, a brake pressure signal, and the like input to the ECT_ECU 1020. It is done. If the vehicle is stopped (idle state) (YES in S100), the process proceeds to S200. Otherwise (NO in S100), this process ends. Note that the flowchart shown in FIG. 3 is a subroutine, and when this process is ended, the process returns to the main routine.

  In S200, ECT_ECU 1020 determines whether or not variable cylinder control is being executed. This determination is made based on a variable cylinder execution signal (partial cylinder control execution) input from engine ECU 1010 to ECT_ECU 1020. If engine 100 is executing variable cylinder control (partial cylinder operation state) (YES in S200), the process proceeds to S600. If not (NO in S200), the process proceeds to S300.

  In S300, ECT_ECU 1020 determines whether or not the N control permission condition is satisfied. This determination is made based on a throttle opening signal, a brake pressure signal, an accelerator opening signal, and the like input to ECT_ECU 1020. If neutral control is permitted (YES in S300), the process proceeds to S400. Otherwise (NO in S300), this process ends.

  In S400, ECT_ECU 1020 starts neutral control. The ECT_ECU 1020 performs feedback control on the input clutch C1 engagement pressure command signal so that the speed ratio in the torque converter 200 becomes the target speed ratio. By executing this neutral control, the speed ratio in the torque converter 200 becomes the target speed ratio, the torque required for the engine 100 is reduced, and the fuel efficiency improvement effect is generated.

  In S500, ECT_ECU 1020 sets the target hydraulic pressure of input clutch C1 in the neutral control to the target hydraulic pressure (2). Thereafter, the process ends.

  In S600, ECT_ECU 1020 determines whether or not N control is permitted. This process is the same process as S300 described above.

  In S700, ECT_ECU 1020 starts neutral control. The process in S700 is the same as the process in S400 described above.

  In S800, ECT_ECU 1020 sets the target oil pressure of input clutch C1 in the neutral control to target oil pressure C (1). This target oil pressure (1) is lower than the target oil pressure (2).

  According to the flowchart shown in FIG. 3, when the variable cylinder control is being executed (partial cylinder operation state), the target hydraulic pressure of the input clutch C1 when the neutral control is executed is low, and the variable cylinder control is not being executed. The target hydraulic pressure of the input clutch C1 when neutral control is executed in the (all cylinder operating state) is set to a high hydraulic pressure.

  An operation of a vehicle equipped with ECT_ECU 1020 that is a vehicle control apparatus according to the present embodiment based on the above-described structure and flowchart will be described.

  When the vehicle equipped with the variable cylinder control device and the neutral control device stops at the intersection of a red signal, the driver releases the accelerator pedal, depresses the brake pedal, and the automatic transmission 300 is in the forward travel position (D position). If variable cylinder control is being executed (partial cylinder is operating) (YES in S100, YES in S200, YES in S600), neutral control is started (S700). At this time, the target hydraulic pressure of the input clutch C1 in the neutral control is set low (S800).

  On the other hand, even when the vehicle is stopped at the intersection of red light or when variable cylinder control is not being executed (all cylinders are operating) (NO in S200, YES in S300), neutral control is performed. Is started (S400). At this time, the target oil pressure of the input clutch C1 in the neutral control is set to a normal target oil pressure (higher oil pressure than when the partial cylinder is operated by variable cylinder control).

  FIG. 4 shows changes over time in the engagement pressure (target pressure, command pressure) of the input clutch C1.

  The solid line shows the time change curve of the engagement pressure of the neutral clutch C1, and corresponds to the case where the control for lowering the target hydraulic pressure is executed by the ECT_ECU 1020 according to the present embodiment. It can be seen that the time until the speed ratio of the torque converter 200 reaches a certain region is short.

  The alternate long and short dash line indicates a time change curve of the engagement pressure of the neutral clutch C1, and corresponds to a case where the control for lowering the target hydraulic pressure is not executed by the ECT_ECU 1020 according to the present embodiment. It can be seen that the time until the speed ratio of the torque converter 200 reaches a certain region is long.

  FIG. 4 shows a state where only three cylinders of the six cylinders of the engine 100 are operated by variable cylinder control in any case.

  As shown in FIG. 4, when the ECT_ECU 1020 according to the present embodiment executes control for setting the target hydraulic pressure of the input clutch C1 to be low during the neutral control, the torque converter 200 has a target speed ratio as shown by a solid line. Thus, the engagement pressure of the input clutch C1 is feedback-controlled so that it takes a short time to reach a region where the speed ratio is constant. On the other hand, when the partial cylinder control is executed, if the target hydraulic pressure of the input clutch C1 during the neutral control remains high as in the prior art, the time required to reach a region where the speed ratio of the torque converter 200 is constant. Takes a long time.

  As can be seen by comparing FIG. 4 and FIG. 6, the time for the speed ratio to reach a constant region when neutral control is performed in all cylinder operation (6 cylinders) is also neutral control in the case of partial cylinder operation (3 cylinders). When the above is performed, the time until the speed ratio becomes a constant region is similar. That is, the ECT_ECU 1020 according to the present embodiment can make the time from the start of the neutral control to the time when the speed ratio of the torque converter 200 reaches a constant range regardless of whether or not the variable cylinder control is executed. it can. For this reason, the ECT_ECU 1020 according to the present embodiment can cause the fuel efficiency improvement effect by the neutral control to appear more quickly than when the target hydraulic pressure of the input clutch C1 is not lowered when the partial cylinder control is being performed.

  In the embodiment described above, the torque converter has been described as a component, but the torque converter is not an essential component of the present invention. Even when there is no torque converter, the present invention can be applied.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a control block diagram of a power train including ECT_ECU which is a vehicle control apparatus according to an embodiment of the present invention. It is an operation | movement table | surface of the automatic transmission shown in FIG. It is a figure which shows the control structure of the program of the neutral control process performed by ECT_ECU. It is a timing chart which shows the time change of the engagement pressure of the input clutch C1 in the automatic transmission of the vehicle carrying ECT_ECU which is a control apparatus which concerns on embodiment of this invention. It is a figure which shows the relationship between the speed ratio of a torque converter, and a capacity coefficient. It is a timing chart which shows the time change of the engagement pressure of the input clutch C1 in the automatic transmission of the vehicle carrying the conventional ECT_ECU.

Explanation of symbols

  100 engine, 200 torque converter, 210 lock-up clutch, 220 pump impeller, 230 turbine impeller, 240 stator, 250 one-way clutch, 300 automatic transmission, 310 input clutch, 400 engine speed sensor, 410 turbine speed sensor, 420 Output shaft rotational speed sensor, 1000 ECU, 1010 Engine ECU, 1020 ECT_ECU, 1030 VSC_ECU.

Claims (2)

A neutral control device that releases an input clutch when the vehicle state stops in a forward drive position and satisfies a predetermined condition, and a variable cylinder control device that changes the number of operating cylinders based on the operating state of the engine A control device for an onboard vehicle,
Detecting means for detecting the number of operating cylinders of the engine controlled by the variable cylinder control device;
A vehicle control apparatus comprising: a changing unit for changing a target oil pressure of the input clutch in the neutral control based on the number of operating cylinders of the engine detected by the detecting unit. The change means includes means for reducing the target hydraulic pressure more than when all cylinders are operating when it is determined that partial cylinders are operating based on the number of operating cylinders detected by the detection means. The vehicle control device according to claim 1.

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