JPH03368A - How to control the power unit - Google Patents

Abstract

PURPOSE:To ease the generation of shift shock by switching to high torque valve operating characteristic to start shifting during power-on and shift-up, when the power-on and shift-up are conducted during operation with low torque valve operating characteristic. CONSTITUTION:When the power-on and shift-down speed change of an automatic transmission AT during operation of an engine E with the variable valve timing mechanism VT of inlet and exhaust valves being made to low torque valve operating characteristic, a control unit CU switches the valve operating characteristic to high torque valve operating characteristic, and also starts shifting through a control valve CV. When the power-on and shift-down speed change is completed, the valve operating characteristic is returned to low torque valve operating characteristic. Hence, the reducing quantity of acceleration when the engine rotation is accelerated by receiving a driving force by the inertia on the transmission input side is minimized, and the generation of shift shock can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION A1.Objective of the invention (industrial application field) The present invention consists of 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 at least one of the plurality of intake valves or exhaust valves in one cylinder.
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 by the line, and when the high-speed valve operation characteristic is used, the characteristic is shown by the line H. Both characteristics intersect at the point of engine rotation speed N, and in the region of engine rotation speed Ne<N In the region where N e >Nl,
The torque of the high-speed valve operation characteristic (line A2) is greater 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 necessary to
It is required to minimize the damage as much as possible.

Shocks during such gear shifts include power-on downshifts (downshifts when the accelerator is depressed, and so-called kickdowns).
There is a shift shock at the time.

This will be explained using a power-on downshift from 4th gear to 2nd gear as an example, as shown in FIG.

When the accelerator pedal is suddenly depressed a little before time t1 and a shift command from 4th gear to 2nd gear is output at time t, the shift solenoid output is changed from 4th gear to 2nd gear based on this. Ru. Accordingly, 4th speed clutch pressure P2
decreases, and second-speed clutch pressure P increases.

In the case of this shift, since the power is on, the engine rotation increases as the 4th speed clutch is disengaged, and the input side rotation of the transmission connected to this increases. and,
When the input side rotation of the second speed clutch connected to the input side of the transmission increases until it is synchronized with the output side rotation, engagement of the second speed clutch is completed and the shift is completed.

Note that the engine rotation first increases by an amount corresponding to the increase in the slip amount of the torque converter in response to the depression of the accelerator pedal, and then increases as shown in the figure from time 1+ to t2. The 4th gear clutch pressure also increases slightly because the line pressure increases in response to the depression of the accelerator pedal at the start of gear shifting.

On the other hand, the acceleration G on the output side of the transmission during this shift becomes a little higher (ΔG1
) After that, when the 4th speed clutch is released and the 2nd speed clutch starts to be engaged, the engine speed is increased by receiving the driving force due to inertia on the input side of the transmission. At this time, the acceleration G decreases by ΔG2 as shown in the figure (a negative acceleration occurs), and then increases as shown in the figure due to the drive from the engine in the power-on state. Note that the acceleration at the end of the shift is calculated by an amount corresponding to the difference in gear ratio between 4th and 2nd gears (ΔG
, ) becomes larger.

(Problems to be Solved by the Invention) In the case of a power-on downshift, the above-mentioned acceleration change occurs, which causes a problem of shift shock.

The present invention has been made in view of the above circumstances, and when power-on and downshifting 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 shocks.

1. Structure of the Invention (Means for Solving the Problem) In order to achieve such an object, in the control method of the present invention, while the engine is operating using the low torque valve operating characteristic, downshifting during power-on is performed. When the power-on shift down is completed, the valve operating characteristic is switched to the high torque valve operating characteristic and at the same time a power-on downshift is started, and then, when the power-on downshift is completed, the valve operating characteristic is changed to the low torque valve operating characteristic. I'm trying to get it back to its characteristics.

(Function) When the control is performed using the above method, the valve operating characteristic is switched to the high torque valve operating characteristic while the power-on/downshift is performed. This reduces the amount of decrease in acceleration (ΔG2) when the engine rotation is increased in response to the driving force due to inertia on the transmission input side.

(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 comprises an engine E having a variable valve timing/lift mechanism VT and an automatic transmission AT controlled by a hydraulic control valve Cv. configured. 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. As will be described later, this switching is performed by supplying and discharging a predetermined hydraulic pressure by turning the solenoid valve 91 ON@OFF. 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 1a and 1b are arranged for each mechanism of the engine E, and these pair of intake valves 1a and 1b are connected to a camshaft 2 that is driven at a rotation ratio of 1/2 in synchronization with the rotation of the engine. First low speed cam provided integrally3. Second
Low-speed cam 3', high-speed cam 5, and camshaft 2
The first. It is opened and closed by the action of the second and thirtieth claw arms 7.8.9.

The camshaft 2 is arranged above the engine body at a rotating position, 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 eyebrow 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 la and ib. Moreover, the first
The second low speed cams 3, 3' have high portions 3a t 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 6, and the first to thirtieth lever arms 7.8
is extended to a position above each intake valve air a+1b.

Further, a cam slipper 10 that slides on the low-speed cam 3 is provided on the upper part of the 10th claw arm 7, and a cam slipper 11 that can come into contact with the second low-speed m-cam 4 is provided on the upper part of the 20th claw arm 8. The intake valves la and lb are biased toward the valve closing direction, that is, upward, by valve springs 1θ and 17.

The 30th claw arm 9 is connected to the first and 20th claw 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.
, is slightly extended to the ib side, and a high-speed cam 5 is mounted on the upper part.
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 installed at the claw arm 7.8°9.

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 shaft mechanism is disclosed in detail in, for example, Japanese Unexamined Patent Publication No. 121811/1983.

Next, the variable valve timing
The operation of the lift mechanism VT 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 toward the 30th hook arm 9 by the spring 25. 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 la and lb 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 the intake valves 1a and 1.
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.
It is also possible to minimize the amount of opening time of the intake valve 1b, and furthermore, to create a valve rest state by setting the above-mentioned high portion 3a' to zero and preventing the intake valve 1b from fully opening during low-speed operation. You can do it like this.

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 rack 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, when the engine E is operated at high speed, both intake valves 1a and 1b are operated by 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 for low-speed operation (intake air suitable for high-speed operation can be obtained, and the engine output can be improved).

In the above operation, the opening/closing timing and lift amount of the intake valves 1a+1b based on the first and second low-speed cams 3, 3' are referred to as low-speed valve operating characteristics, and the opening/closing timing and lift amount of the intake valves 1a, 1b based on the high-speed cams 5 are referred to as low-speed valve operating characteristics. The opening/closing timing and lift amount 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 the characteristic shown by line Al-A2 corresponds to high-torque valve operation. The characteristic shown by line B++B2 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 θ2 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 that mesh with each other, namely, 1st speed gear train 51a, 51b, 12th speed gear train 52a, 52b, 3rd speed gear train 53at ssb, 4th speed gear train 54a, 54b
and reverse gear trains 55 a, 55 b, 55
c is provided. Hydraulically operated clutch 6 for selecting each gear train as the driving gear or driven gear of each gear train
4 to 68 are arranged, and these hydraulically operated clutches 6
By selectively operating gears 4 to 68, 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. .

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 is further provided for locking and holding these one-way clutches 56, 57.

Operation control of the lock-up clutch 47 in the automatic transmission AT configured as described above and each clutch 64 of the transmission mechanism 50
The operation control of 69 to 69 is performed by a control valve Cv shown in FIG.

In the power unit configured as described above, when a power-on shift 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/downshift command (step Sl). 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 downshift, the process proceeds to step S2, where it is determined whether the valve operating characteristics of the engine are low torque valve operating characteristics, that is, the characteristics shown by line B or B2 in FIG. It is determined whether or not.

If it is not power-on or downshifting, this flow is not controlled and the process proceeds to the return step. Also,
When the high-torque valve operating characteristic is maintained, the high-torque valve operating characteristic is maintained as it is (step S7) and the process proceeds to the return step.

If the low torque valve operating characteristic is used and a power-on e-shift is performed, step S3
From then on, the control shown in step S6 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 this example shows a power-on downshift from 4th gear to 2nd gear. Simultaneously with the start of this shift, the solenoid valve 91 is operated to switch the valve operating characteristic to a high torque valve operating characteristic.

When the shift starts at time t1, the fourth speed clutch pressure P2 decreases and the second speed clutch pressure P3 increases accordingly. As the fourth-speed clutch is disengaged, the engine rotation increases, and the input rotation of the transmission connected therewith increases. Then, at time t2 when the input side rotation of the second speed clutch connected to the input side of the transmission increases until it is synchronized with the output side rotation, the engagement of the second speed clutch is completed and the shift is completed.

When the completion of this shift is detected based on the input/output rotational speed ratio of the second speed clutch, etc., the process proceeds from step S5 to step S6, where the valve operating characteristics are returned to the original low torque valve operating characteristics, and this flow is ended.

In this shift, the engine rotation first increases by the amount of slip of the torque converter in response to the depression of the accelerator pedal, and then from time t□ to t2.
as shown in the figure. Therefore, the acceleration G on the output side of the transmission during this shift becomes slightly higher (ΔG1+) at the start of the shift in response to the increase in engine rotation due to the increase in torque converter no-slip.

Thereafter, when the 4th speed clutch is released and the 2nd speed clutch starts to be engaged, the engine speed is increased by receiving the driving force due to inertia on the input side of the transmission. At this time, acceleration G
(as shown in the figure, decreases by ΔG12 and negative acceleration occurs), and then increases as shown in the figure due to drive from the engine in the power-on state. Note that the acceleration at the end of the shift is calculated by an amount corresponding to the difference in gear ratio between 4th and 2nd gears (ΔGX
3) becomes larger.

In this way, the high torque valve operating characteristic is used from the shift start time tx to the shift completion time t2, and the engine output during this period is increased.

Therefore, the amount of decrease in acceleration due to inertia of the transmission output image Δ
G12 is smaller than when the valve operating characteristics are not switched and there is no increase in engine output. The acceleration change when the valve operating characteristic is not changed and the gear is shifted with the low torque valve operating characteristic is shown by a broken line in Fig. 9, and the amount of decrease in acceleration in this case is ΔG12 (>
ΔG1□), and as can be seen from this, if the control of the present invention is used, the shift shock will be reduced.

Furthermore, if you switch to high-torque valve operating characteristics when shifting, the engine output will increase, so the engine speed will rise faster during shifting, and the shifting time will be shorter than when the valve operating characteristics are not switched. .

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. 10. Thus, three types of characteristics may be established: low-speed valve operation characteristics, medium-speed valve operation characteristics, and high-speed valve operation characteristics.

In this case, the characteristics shown by lines At, Aa, A3 are high torque valve operating characteristics, and lines B11B21B, 3.
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.

As described in detail, according to the present invention, when a power-on/downshift is performed while the engine is running with a low torque valve operating characteristic, a high torque valve operating characteristic is used during a gear shift. Therefore, during this shift, it is possible to reduce the amount of decrease in acceleration (ΔG2) when the engine rotation speed is increased due to the driving force due to inertia on the transmission input side, thereby alleviating the shift shock. .

[Brief explanation of the drawing]

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 fist 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. FIG. 8 is a flowchart showing the control according to the present invention; FIG. 9 is a graph showing changes over time in various signals during power-on and downshift; 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 and downshifting under conventional control. 3.3'...Low speed cam 5...High speed cam 6...
・Rocker shaft 21...Connection means 22.23・
...Piston 29...Hydraulic chamber 50...Transmission mechanism
63...Transmission input shaft 92...Water temperature sensor
93... Throttle sensor 94... Engine rotation sensor CU... Control unit

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 power-on and downshifting of the automatic transmission is performed while the engine is operating using a low torque valve operating characteristic, the valve operating characteristic is switched to a high torque valve operating characteristic and at the same time the power A method for controlling a power unit, comprising: starting a power-on shift down, and returning the valve operating characteristic to a low torque valve operating characteristic when the power-on shift down is completed.