JPH03366A - Control method of power unit - Google Patents

Abstract

PURPOSE:To ease shift shock by temporarily switching valve operating characteristic to high torque valve characteristic for a determined time at the time of completion of power-on and shift-up, when the power-on and shift-up are conducted during operation with low torque valve characteristic. CONSTITUTION:When power-on and shift-up are conducted during operation of an engine E with a variable valve timing lift mechanism being made to low torque valve operating characteristic, a control unit CU temporarily switches the valve operating characteristic of intake and exhaust valves to high torque valve characteristic at the point of time when the power-on and shift-up are completed. After the lapse of a determined time, the valve operating characteristic is returned to low torque valve operating characteristic. Hence, reduction in acceleration when the shift is completed is minimized, and shift shock can be eased by this extent.

Description

DETAILED DESCRIPTION OF THE INVENTION A.Objective of the invention (industrial application field) The present invention comprises an engine whose valve operating characteristics can be freely changed, and a transmission connected to the output shaft of the engine. Regarding the power unit.

Note that switching the valve operating characteristics refers to switching the opening/closing timing and opening period of the intake valve or exhaust valve, and/or the valve lift amount, and it means switching the opening/closing timing and opening period of the intake valve or exhaust valve, and/or the valve lift amount. 1
It also includes switching the open period of two valves to substantially zero and switching them to a closed state.

(Prior Art) Conventionally, according to Japanese Patent Publication No. 49-33289, the valve operating characteristics of at least one of the intake valve and the exhaust valve have been changed into a low-speed valve operating characteristic suitable for a low-speed region and a high-speed valve operating characteristic suitable for a high-speed region. Engines that can freely switch valve operating characteristics are known. In this engine, the engine speed is below a predetermined value and the intake negative pressure is below a predetermined pressure (
The valve operating characteristics are switched to low-speed valve operating characteristics in the area (vacuum side), and switched to high-speed valve operating characteristics in other areas.

FIG. 6 shows an example of the output characteristics of such an engine. When the low-speed valve operation characteristic is used, the characteristic is shown as a line, and when the high-speed valve operation characteristic is used, the characteristic is as shown by the line H. Both characteristics intersect at the point of engine rotation speed N1, and in the region of engine rotation speed Ne<N1, the torque of the low-speed valve operation characteristic (line A) is larger than the torque of the high-speed valve operation characteristic (line B+), In the region of Ne>N1, the torque of the high-speed valve operation characteristic (line A2) is larger than the torque of the low-speed valve operation characteristic (line B2). In this case, the characteristics with larger torque (characteristics shown by lines A□ and A2) are called high-torque valve operating characteristics, and the characteristics with smaller torque (characteristics shown by lines B□ and B2) are called low-torque valve operating characteristics. It is called a characteristic.

On the other hand, an automatic transmission is configured to automatically change gears depending on the driving condition to obtain desired driving characteristics.

For this reason, for example, it is possible to have a shift map in which upshift lines and downshift lines are set for each shift based on the relationship between vehicle speed and engine output, and to perform shift control by comparing the driving condition with this shift map. Well done. As an example of such speed change control, for example,
There is one disclosed in Japanese Patent No. 189354.

When performing such shift control, it is required to reduce shock during shift as much as possible.

Such a shock during a shift includes a shift shock during a power-on shift up (shift up with the accelerator being depressed).

This will be explained using a power-on shift-up from 2nd speed to 3rd speed as an example, as shown in FIG.

Time t! At this point, a shift command from 2nd speed to 3rd speed is output, and based on this, the shift solenoid output is changed from 2nd speed to 3rd speed. Correspondingly, the second speed clutch pressure P2 decreases and the third speed clutch pressure P3 increases.

For this reason, the engine torque that was previously transmitted only to the 2nd speed clutch is also divided to the 3rd speed clutch and gradually transfers to the 3rd speed clutch. This transition is completed at time t2, and the transition from time t to time t2 is referred to as a torque phase. Due to this transition, the gear ratio (reduction ratio) in the transmission changes to become smaller, so the engine torque is pulled into the transmission side and rarely decreases, and the acceleration G on the transmission output side is shown in graph (e). It decreases as shown in .

After this, torque is transmitted by the second-speed clutch, and the engine rotation decreases as shown in the figure.At this time, due to the inertia of the input side of the engine and transmission, the acceleration G of the transmission output decreases as shown in the figure. Rise. Then, at time t3 when the gear shift is completed, the acceleration G returns to the original level. The period from time t2 to t3 is referred to as an inertial phase.

(Problems to be Solved by the Invention) As described above, when a power-on shift-up is performed, a change ΔG1 in acceleration G in the torque phase and □ changes ΔG2 and ΔG3 in acceleration G in the conventional phase occur. There is a problem in that shift shock occurs due to changes in acceleration.

Note that this power-on shift-up is automatically performed when the accelerator pedal is pressed and the vehicle speed increases while driving, and is a shift that is performed regardless of the driver's intention, so there is no chance of a shift shock occurring. It is desirable to keep it as small as possible.

The present invention has been made in view of the above circumstances, and when the power-on shift-up of the transmission is performed, the shift control and the switching control of the valve operating characteristics of the engine are controlled in conjunction with each other, and the above-described control is performed. It is an object of the present invention to provide a control method that can reduce such acceleration changes and suppress shift lock.

9. Structure of the Invention (Means for Solving the Problems) In order to achieve such an object, in the control method of the present invention, a power monoshift upshift is performed while the engine is operating using the low torque valve operating characteristic. When the power-on shift-up is completed, the valve operating characteristic is switched to the high-torque valve operating characteristic, and after a predetermined time delay, the valve operating characteristic is changed to the high-torque valve operating characteristic. The valve is designed to return to its low-torque valve operating characteristics.

(Function) When control is performed using such a method, when the power-on upshift is completed, the valve operating characteristic is switched to the high-torque valve operating characteristic, and the engine output is increased. Therefore, the decrease in acceleration (ΔG3 in FIG. 11) at the completion of the shift becomes small, and the shift shock decreases accordingly.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a power unit controlled by the method according to the invention, which includes an engine E having a variable valve timing/lift mechanism VT, and an automatic transmission AT controlled by a hydraulic control valve Cv. It consists of Here, the variable valve timing/lift mechanism VT adjusts the opening/closing timing, opening period, and lift amount of the intake valves of the engine E into low-speed valve operating characteristics suitable for the low-speed region and high-speed valve operating characteristics suitable for the high-speed region. This switching is performed by supplying and discharging a predetermined hydraulic pressure by turning on and off the solenoid valve 91, as will be described later. Further, the hydraulic control valve Cv is a valve that performs engagement control of the lock-up clutch in the automatic transmission AT, operation control of the speed change clutch, etc., and this operation control is performed by the solenoid valves 251 and 25.
2.253,255.

The above solenoid valve 91, 251, 252° 253.
The operation of 255 is controlled by an operation signal from the control unit CU. Therefore, the control unit CU includes an engine cooling water temperature signal from the water temperature sensor 92, a throttle opening signal from the throttle sensor 93,
Various signals such as an engine rotation signal from an engine rotation sensor 94 and a transmission output rotation signal from a transmission rotation sensor 95 are input, and based on these various signals, an activation signal is sent from the control unit CU to each of the solenoid valves. is output.

First, the variable valve timing/lift mechanism VT will be explained with reference to FIGS. 2 and 3. A pair of intake valves 1aslb is provided for each mechanism of the engine E, and these pair of intake valves la, lb are integrally connected to a camshaft 2 that is driven at a rotation ratio of 1/2 in synchronization with the rotation of the engine. The first low speed cam 3. Second
Low-speed cam 3', high-speed cam 5, and camshaft 2
The first one is pivotally supported on a rocker shaft 8 parallel to the It is opened and closed by the action of the second and thirtieth claw arms 7.8.9.

The camshaft 2 is rotatably disposed above the engine body, and the first low-speed cam 3 is connected to one intake valve 1a.
is provided integrally with the camshaft 2 at a position corresponding to
The second low-speed cam 3' is integrally provided on the camshaft 2 at a position corresponding to the other intake valve 1b. Further, the high-speed cam 5 is integrally provided on the camshaft 2 at a position corresponding to between both intake valves 1a and ib. Moreover, the first
The second low speed cams 3, 3' have high portions 3a, 3a' corresponding to low speed operation of the engine.

The high-speed cam 5 has a high portion 5a suitable for high-speed operation of the engine.

First to thirtieth lever arms 7 to 9 are respectively pivotally supported on the rocker shaft 8, and the first to thirtieth lever arms 7.8
is extended to a position above each intake valve la, lb.

Further, a cam slipper 10 that slides on the low-speed cam 3 is provided at the top of the tenth claw arm 7, and a cam slipper 11 that can come into contact with the second low-speed cam 4 is provided on the top of the 20th claw arm 8. Note that each of the intake valves la and lb is biased by valve springs 18 and 17 in the valve-closing direction, that is, upward.

The 30th hook arm 9 is connected to the first and 20th hook arms 7.
．． It is pivotally supported on the rocker shaft 6 between 8 and 8. This 30th lever arm 9 connects both intake valves 1a to the rocker shaft 6.
It extends slightly to the +1b side, and a high-speed cam 5 is mounted above it.
A cam slipper is provided that slides into contact with the cam slipper.

As shown in FIG. 3, the first to 30th claw arms 7.8.
9 are in sliding contact with each other, and a connecting means 21 that can switch between a state that allows relative angular displacement thereof and a state that integrally connects each rocker arm 7 to 9 is connected to the first to 20th rocker arms 7 to 9.
It is provided at the claw arm 7.8°8.

The connecting means 21 has a first piston 22 movable between a position where the first and 30th lever arms 7.9 are connected and a position where the connection is released, and a position where the third and 20th lever arms 7.9 are connected and A second piston 23 that is movable between positions where the connection is released; a stopper 24 that restricts movement of the first and second pistons 22 and 23;
and a spring 25 that biases the stopper 24 to move the second piston 22, 23 to the disconnection position.

The movement of these first and second pistons 22.23 is caused by the movement of the oil passage 31.32.3 in accordance with the operation of the solenoid valve 91.
This is done by the hydraulic pressure supplied into the hydraulic chamber 29 through 0.

Note that such a variable valve timing lift mechanism is disclosed in detail in, for example, Japanese Unexamined Patent Publication No. 121811/1983.

Next, the operation of the variable valve timing lift mechanism VT configured as described above will be explained.

When the engine E is operating at low speed, the solenoid valve 91 is OFF, and the oil passage 31 and the oil pressure source (
(not shown), and the connection switching means 21
Hydraulic pressure is not supplied to the hydraulic chamber 29, and the stopper 24 is pressed by the spring 25 toward the 30th lever arm θ. Each rocker arm 7.8.9 is therefore independently displaceable.

When the connection switching means 21 is in the disconnected state,
Due to the rotational movement of the camshaft 2, the tenth lever arm 7
swings in response to sliding contact with the first low-speed cam 3, and the 20th claw arm 8 swings in response to sliding contact with the second low-speed cam 3'. Therefore, both intake valves 1aylb are opened and closed by the first and second low-speed cams 3, 3'. At this time, the 30th lever arm 9 swings due to sliding contact with the high-speed cam 5, but the swinging movement is caused by both intake valves la and l.
It has no effect on the operation of b.

In this way, when the engine E is operating at low speed, the 5th A
As shown by a broken line 3 and a dashed-dotted line 3' in the figure, one intake valve 1a opens and closes at a timing and lift amount according to the shape of the first low-speed cam 3, and the other intake valve 1b operates as a second low-speed cam 3. It opens and closes with timing and lift amount depending on the shape of the cam 3'. Therefore, a mixture flow rate suitable for low-speed operation can be obtained, reducing fuel consumption and preventing sparkling, and allows optimum low-speed operation to be performed.

In addition, in order to obtain a mixture flow speed suitable for low-speed operation,
For example, as shown in FIG. 5B, the high part 3a' of the second low-speed cam 3' is lowered to lower the intake valve 1b during low-speed operation.
The opening time and amount of the intake valve 1b may be made extremely small, and furthermore, the above-mentioned high portion 3a' may be set to zero so that the intake valve 1b is not opened at all during low speed operation to create a valve rest state. You can also do it.

When operating engine E at high speed, solenoid valve 9
1 is ON, and as shown in FIG. 4, the hydraulic pressure source (not shown) and the oil passage 31 are communicated by the solenoid valve 91, and the hydraulic pressure is supplied to the hydraulic chamber 29 of the connection switching means 21. . As a result, as shown in FIG. 4, the first and second pistons 22.23 move until the stopper 24 comes into contact with the restriction step 36, and the first piston 22 causes the first and 30th lever arms 7.9 to move. are connected, and the third and twentieth hook arms 9, 8 are connected by the second piston 23.

In this manner, when the first to thirtieth lever arms 7°8.9 are connected to each other by the connection switching means 21,
Since the amount of swing of the 30th claw arm 9 in sliding contact with the high speed cam 5 is the largest, the first and 20th claw arms 7.8 swing together with the 30th claw arm 9. Therefore, during high-speed operation of the engine E, both intake valves 1allb are moved to the high-speed cam 5, as shown by the solid line 5 in FIG. 5A.
It opens and closes with timing and lift amount depending on the shape of the door. The timing and lift amount in this case are larger than those during low-speed operation, so that intake air suitable for high-speed operation can be obtained, and the engine output can be improved.

In the above-described operation, the opening/closing timing and lift amount of the intake valves la, lb based on the first and second low-speed cams 3 and 3' are referred to as low-speed valve operating characteristics, and the intake valves la, lb based on the high-speed cams 5 are referred to as low-speed valve operating characteristics. The opening/closing timing and lift amount of lb are referred to as high-speed valve operation characteristics. Both valve operating characteristics are used separately for a low-speed operation region and a high-speed operation region, and the relationship between the engine output torque and the engine rotational speed at this time is as shown in FIG. As mentioned above, in this figure, the line indicates the characteristic in low-speed valve operation characteristic operation, the line H indicates the characteristic in high-speed valve operation characteristic operation, and line A1. The characteristic indicated by A2 is the high torque valve operating characteristic, and the characteristic indicated by line BttB2 is the low torque valve operating characteristic.

Next, the automatic transmission AT will be explained based on FIG. 7.

This automatic transmission AT is composed of a torque converter 40 and a transmission mechanism 50, and the torque converter 40 is connected to an engine output shaft E. It consists of a pump 46a connected to P, a turbine 46b connected to an output shaft (transmission mechanism input shaft) 61, and a fixedly held stator 46c.
It has a lock-up clutch 47 that can freely engage and disengage the turbine 46b and the turbine 46b.

The transmission mechanism 50 includes an input shaft 61 integrated with the torque converter output shaft, a counter shaft 62 parallel to this, and an output shaft 63.
has. Between the input shaft 61 and the counter shaft 62, there are five sets of gear trains meshing with each other, namely, 1st speed gear trains 51a, 51b, 2nd speed gear trains 52a, 52b, 13th speed gear trains 53a, 58b, 14th speed gear trains 54a, 54b. and a reverse gear train 55 al 55 b + 55 c are provided. Hydraulically operated clutches 64 to 6 for selecting each gear train as the driving gear or driven gear of each gear train
8 are arranged, and these hydraulically operated clutches 64 to 6
By selectively operating 8, the power transmission path by one of the gear trains is selectively switched, and the speed is changed.

Output gear trains 59a and 59b are disposed between the counter shaft 62 and the output shaft 63, and the power shifted as described above is transmitted to the output shaft via the output gear trains 59a and 59b. be done.

Note that one-way clutches 56.57 are attached to the first-speed driven gear 51b and the second-speed driven gear 52b, and an engine clutch 69 for locking and holding these one-way clutches 5E3.57 is also provided.

Operation control of the lock-up clutch 47 in the automatic transmission AT configured as described above and each clutch 84 of the transmission mechanism 50
The operation control of 69 to 69 is performed by the control valve CV shown in FIG.

In the power unit configured as described above, when a power-on shift-up is performed, the variable valve timing/lift mechanism VT of the engine E controls switching of valve operating characteristics, and the hydraulic control valve Cv controls the switching of the transmission mechanism 50. The operation control will be explained with reference to the control flow shown in FIG.

In this control, first, it is determined whether the shift command is a power-on shift-up (step 81). Note that the power-on state refers to a state in which the throttle opening is opened by, for example, pressing the accelerator pedal. If it is a power-on shift up, the process proceeds to step S2, where it is determined whether the engine valve operating characteristic is a low torque valve operating characteristic, that is, whether it is the characteristic indicated by line B1 or B2 in FIG. will be judged.

When there is no power-on shift-up or low torque valve operating characteristics, this flow is not controlled and the process proceeds to the return step.

If the low torque valve operating characteristic is used and a power-on upshift is performed, step S3
From then on, the control shown in step S8 is performed, which will be explained with reference to the graph of FIG.

First, at time t1 when a shift command is issued, a shift solenoid (solenoid valve in FIG. 1) is operated to start shifting based on the shift command (step 83). Note that here, a case of power-on upshift from 2nd speed to 3rd speed is shown. When the shift starts at time t1, the engine torque that had been transmitted only to the 2nd gear clutch side is also divided to the 3rd gear clutch side and gradually transfers to the 3rd gear clutch side, and this transition is completed at time t2. . That is, the period from time t1 to time t2 is the torque phase. Due to this transition, the gear ratio (reduction ratio) in the transmission changes to become smaller, so the engine torque is pulled into the transmission side and decreases, and the acceleration G on the transmission output side decreases as shown in the graph. do.

From time t2, the engine shifts to the inertia phase, the third speed clutch starts to engage, and the engine rotation decreases as shown. In this inertia phase, the transmission output side acceleration G increases as shown in the figure due to the inertia of the input side of the engine and the transmission, and then returns to the original state at the shift completion time t3.

However, the time point at which this shift is completed is detected from the engine rotation, the input/output rotation speed ratio of the shift clutch, etc., and when the shift completion is detected (step S4), the process proceeds to step S5, and this shift is completed. A predetermined delay time To is calculated from the pattern, the engine output at this time, and the like.

At the time when the completion of the shift is detected, the valve operating characteristic of the engine is switched to the high torque valve operating characteristic at the same time as the above calculation. When this valve operation characteristic switching is performed, the engine output torque increases, so that the decrease ΔG in the acceleration G on the transmission output side in the inertial phase is suppressed by an amount corresponding to the increase in the engine output. For this reason, the change in acceleration at the time of completion of the shift becomes small, and the shift shift is alleviated.

Next, after waiting for the delay time TD to elapse in step S7, the valve operating characteristic is returned to the original low torque valve operating characteristic (step S8), and the present control is completed.

The embodiments of the present invention have been described above, but instead of setting only two types of valve operating characteristics, high-speed valve operating characteristics and low-speed valve operating characteristics, as shown in FIG. 6, as shown in FIG. Thus, three types of characteristics may be set: low-speed valve operation characteristics, medium-speed valve operation characteristics, and high-speed valve operation characteristics.

In this case, the characteristic shown by the line A□+A2*A3 is the high torque valve operating characteristic, and the characteristic shown by the line B1+B2mB5.
The characteristic indicated by B4 is the low torque valve operating characteristic. Furthermore, it is a matter of opinion that four or more types of characteristics may be set.

C1 Detailed Description of the Invention According to the present invention, when a power-on shift-up is performed while the engine is operating using the low-torque valve operating characteristic, when the power-on shift-up is completed, , the valve operating characteristics are switched to high-torque valve operating characteristics, and then after a predetermined time delay, the valve operating characteristics are returned to low-torque valve operating characteristics, so that the high-torque valve operating characteristics are activated upon completion of the power-on upshift. Switching to the characteristic increases engine power. Therefore, the drop in acceleration upon completion of the shift becomes smaller, and the shift shock can be alleviated accordingly.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a power unit controlled by the method according to the present invention; FIG. 2 is a sectional view of a variable valve timing-lift mechanism used in an engine constituting the power unit; FIGS. 3 and 4. The figure is a cross-sectional view of this mechanism, Figures 5A and 5B are graphs showing the opening/closing operation characteristics of the intake valve, Figure 6 is a graph showing the relationship between the output torque and rotational speed of the engine, and Figure 7 is the graph shown above. A schematic diagram showing a power transmission system of an automatic transmission that constitutes a drive unit, FIG. 8 is a flowchart showing control according to the present invention, and FIG. 9 is a graph showing changes over time in various signals during power-on and upshifting. FIG. 10 is a graph showing the characteristics of an engine having three types of valve operating characteristics, and FIG. 11 is a graph showing changes over time in various signals during power-on shift-up under conventional control. 3.3'...Low speed cam 5...High speed cam 6...
・Rocker shaft 21...Connection means 22.23-
... Piston 29 ... Hydraulic chamber 47 ... Lock-up clutch 50 ... Transmission mechanism 83 - ... Transmission input shaft 9
2...Water temperature sensor 93...Throttle sensor 84...Engine rotation sensor 95...Transmission rotation sensor CU...Control unit VT...Variable valve timing/lift mechanism

Claims (1)

[Scope of Claims] 1) A method for controlling a power unit comprising an engine capable of freely changing the valve operating characteristics of at least one of an intake valve and an exhaust valve, and an automatic transmission connected to the output shaft of this engine. and when a power-on upshift of the automatic transmission is performed while the engine is operating using a low torque valve operating characteristic, the power-on upshift is initiated; 1. A method for controlling a power unit, characterized in that upon completion of the step, the valve operating characteristic is switched to a high-torque valve operating characteristic, and after a predetermined time delay, the valve operating characteristic is returned to a low-torque valve operating characteristic.