JP2887980B2 - Engine output control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output control device for an engine having an automatic transmission and a variable valve mechanism for switching a cam depending on operating conditions, and more particularly to an automatic transmission capable of operating an engine brake.

[0002]

2. Description of the Related Art A valve train for driving an intake and exhaust valve of an engine is set so as to obtain an optimal valve timing in accordance with an output characteristic required by the engine.

However, the required valve timing differs depending on the operating conditions of the engine. For example, in a low load range, the valve lift and the valve opening period are both small, whereas in a high load range, a large valve lift and the valve opening period are required. Is done. In the case of an engine having a wide range of operating conditions, such as an automobile engine, it is very difficult to determine the valve timing in which operating region, and in any case, it is not possible to achieve optimum matching under all operating conditions.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 63-167016, a plurality of cams having different cam characteristics (cam profiles) are provided, and the cams are switched according to the operating conditions. There has been proposed a variable valve operating device capable of operating at a timing.

[0005] This is to switch between a low-speed cam having a high torque in a low rotation range and a high-speed cam having a high torque characteristic in a high rotation range according to operating conditions. It is to try to make it.

[0006]

Some automatic transmissions are provided with a one-way clutch in order to reduce the shift shock during downshifting. This one-way clutch transmits the driving force from the engine to the drive shaft (wheels), but the reverse driving force from the driving wheels does not transmit to the engine because the one-way clutch idles, so the select lever is moved from the D range to the two ranges to reduce the speed. And when operating in one range, the engine brake cannot be applied.

[0007] Accordingly, by over-clutching the transmission element provided between the transmission elements before and after the one-way clutch as necessary to prevent idling of the one-way clutch,
The engine brake is operated in the same manner as before, and the effectiveness of the engine brake is adjusted by changing the operating oil pressure to the overrun clutch.

However, when the cam is switched to the low output side cam as described above due to a decrease in the engine speed in a state where the overrun clutch is engaged with a constant operating oil pressure, in addition to the engine brake due to downshifting, Since the engine brake by the cam switching control to the low output side is superimposed, the deceleration suddenly increases and the driving feeling deteriorates.

Although the magnitude of the reverse driving force transmitted from the road surface to the engine via the driving wheels is equal to that before the cam switching, the driving force of the engine is smaller than that before the switching, so that the engine is rotated in the reverse direction. The power becomes relatively large,
The engine brake suddenly starts to work greatly. Since such a phenomenon does not occur in an engine having only one cam, the driver feels discomfort and anxiety due to discontinuous change in deceleration.

If the driver further depresses the accelerator pedal assuming that the engine brake is working too much during the operation, the cam is switched again to the cam having the higher output, and in this case, the acceleration exceeding the driver's expectation is increased. Therefore, it is difficult to perform the deceleration operation.

As a solution to this, if the overrun clutch is released in synchronization with the switching of the cam to the low output side, the engine brake does not suddenly work greatly during the deceleration. The engine brake will not work at all during slow deceleration.

Therefore, the present invention secures engine braking by weakening the engagement force of the overrun clutch in synchronism with the cam switching when the cam switches to the low output cam during engagement of the overrun clutch. It is another object of the present invention to prevent the engine brake from acting suddenly during deceleration.

In the first invention, as shown in FIG. 1, the one-way clutch 91 transmits the driving force from the engine to the driving wheels, but does not transmit the reverse driving force from the driving wheels to the engine.
And an overrun clutch 92 for engaging and disengaging the transmission elements before and after the one-way clutch 91 in response to the operating oil pressure, and operating conditions (e.g., select lever position and accelerator position) to determine whether the overrun clutch 92 has been engaged. Opening degree), and an automatic transmission having an overrun clutch engagement mechanism 94 that supplies operating hydraulic pressure to engage the overrun clutch when the engagement condition is satisfied, while having different output characteristics. A plurality of cams 95 having cam profiles and means 96 for determining whether to switch these cams according to operating conditions
And a cam switching mechanism 97 for selectively switching these cams in accordance with the determination result and transmitting the movement of the cams to at least one of the intake and exhaust valves. Means 98 for determining whether or not the cam is switched to the low output cam while the engagement of the overrun clutch 92 is in progress, and the engagement force of the overrun clutch 92 in synchronization with the switching of the low output cam.
And reverse drive force transmitted from the drive wheels to the engine
And a means 99 for reducing the size . The second invention is an en
The drive force from the gin is transmitted to the drive wheels,
One-way clutch 91 that does not transmit reverse driving force to engine
In response to the operating oil pressure, the one-way clutch 91
Overrun clutch that engages and releases the front and rear transmission elements
92 and the fastening conditions of this overrun clutch 92.
Means 93 for determining from the operating conditions whether or not
When operating conditions are met, hydraulic pressure is supplied to
Overrun clutch to engage clutch 92
Output mechanism with an automatic transmission having a mechanism 94;
Cams 95 with different cam profiles
Judge whether to switch these cams according to the operating conditions.
Means 96, and these cams are selected in accordance with the determination result.
Selective switching and the movement of this cam
At least one of which is provided with a cam switching mechanism 97 for transmitting to one side.
In the engine output control device, the overrun
Circuit for independently controlling the operating oil pressure to the switch fastening mechanism 94
And the overrun clutch 92
The cam is switched to the low output cam during the fastening.
A means 98 for determining whether, in the lower output cam
The overrun clutch fastening mechanism 94 is synchronized with the switching.
Only the operating oil pressure to the overrun clutch 92.
A reverse drive that reduces the binding force and transmits it from the drive wheels to the engine
Means 99 for controlling the power in a direction to reduce the power .
In each of the above inventions, the overrun clutch is
The lower the vehicle speed after replacement, the lower the fastening force
The reverse driving force transmitted from the driving wheels to the engine will be smaller
Control.

[0014]

In each of the above-mentioned inventions, if the engagement condition of the overrun clutch 92 is satisfied by moving the select lever from the D range to, for example, two ranges to release the accelerator and releasing the accelerator pedal, the overrun clutch 92 is engaged and the drive is started. The reverse driving force from the wheels is transmitted to the engine, and the engine brake works.

On the other hand, when the engine speed is reduced by returning the accelerator pedal, and the cam is switched to a low output cam while the overrun clutch 92 is engaged, the overrun clutch is synchronized with the cam switching. 92 becomes weaker, that is, the reverse driving force from the driving wheels to the engine
The torque acting as becomes smaller .

If the driving force of the engine becomes relatively smaller than the reverse driving force transmitted from the driving wheels to the engine due to the cam switching during the engagement of the overrun clutch, the load on the engine increases and the engine brake suddenly increases. However, if the reverse driving force is reduced by weakening the overrun clutch engagement force,
The relationship between the engine driving force and the reverse driving force is kept substantially the same as before the cam switching.

[0017] Thus, without deceleration obtained by engine brake changes discontinuously before and after the cam switching, also operations such as increasing depression of the accelerator pedal in a hurry to sudden loud engine braking in the middle No longer needed. In each of the above inventions,
The clutch engagement force is weaker as the vehicle speed after switching the cam is lower.
As a result, the reverse driving force transmitted from the drive wheels to the engine is small.
The vehicle speed at the time of cam switching is controlled by controlling
A more appropriate engine brake suppression effect
Can be.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIG. 2 and FIG. 3 show a specific structure of a variable valve apparatus according to an embodiment, which has already been proposed by the present applicant as Japanese Patent Application No. 2-117261. .

Reference numeral 21 designates a fuel efficiency-oriented cam profile in which both the cam lift and the lift section are small.
A cam (fuel consumption cam) 22 is set to a cam profile that generates a high torque in a low rotation range, and a second cam (low-speed output cam) having a cam lift relatively larger than the first cam 21 and a high rotation cam 23. A third cam (high-speed output cam) which is set to a cam profile that generates a high torque in the region and has a cam lift and a lift section larger than the second cam 22 is provided in parallel on the same cam shaft.

Reference numeral 24 denotes an intake / exhaust valve (an intake valve or an exhaust valve). Reference numeral 25 denotes a main rocker arm which is always in contact with the first cam 21 via a roller 26. Opening and closing the exhaust valve 24;

The main rocker arm 25 has a shaft 3
Two sub rocker arms 2 that swing about 0
8 and 29 are supported in parallel with the roller 26, and one sub rocker arm 28 contacts the second cam 22 and the other sub rocker arm 29 contacts the third cam 23.

When the sub rocker arms 28 and 29 are not engaged with the main rocker arm 25, they are urged by the lost motion spring 31 so as to always contact the second and third cams 22 and 23. It moves (oscillates) independently of the arm 25.

In order to selectively engage the sub rocker arms 28 and 29 with the main rocker arm 25, first, a cylindrical pin 32 is provided at the swinging portion of one of the sub rocker arms 28, and the main rocker arm 25, a pin 34 is coaxially arranged with the pin 32 so as to be slidable in the direction of the camshaft.
2 are kept in the state shown in FIG. 2 by being urged by the return spring 36, and are disengaged from the main rocker arm 25.
When the pressurized oil is led to the passage 8 through the passage 40, the pins 32 and 3
4 is pushed out by a predetermined amount, and the sub rocker arm 28 is pushed out.
Are adapted to engage with the main rocker arm 25.

The reason that the sub rocker arm 28 is integrated with the main rocker arm 25 is that the first cam 21 and the second
When the cam 22 is in the base circle, the first
The valve timing is switched according to the second cam 22 having a larger lift than the cam 21.

That is, the characteristic of the first cam 21 focusing on fuel consumption is switched to the characteristic of the second cam 22 focusing on output in a low rotation range.

The other sub-rocker arm 29 is similarly constructed, and when pressure oil is introduced into the hydraulic chamber 39 via the passage 41, the pins 35 and 33 are pushed out against the return spring 37, Sub rocker arm 2
9 engages with the main rocker arm 25,
The valve timing is switched so as to depend on the third cam 23 having a larger lift and lift section than the first cam 21 in the same manner as described above, so that a characteristic that emphasizes output in a high rotation range is obtained.

FIG. 4 shows the first cam 21 to the third cam 2.
3 shows valve lift characteristics up to 3. The full-open output characteristics when each cam is used are as shown in FIG. 5. According to the first cam, although the generated torque is low, the fuel efficiency is good, and the second cam is good.
The cam has the highest maximum torque in the low rotation range, and the third cam 23 generates less torque in the low rotation range than the second cam 22 but has the largest torque in the high rotation range.

By the way, switching from the first cam 21 to the second and third cams 22 and 23 and vice versa.
A control unit 51 as shown in FIG. 6 is provided for controlling the switching from 2, 23 to the first cam 21,
The optimum cam is selected according to the operating condition.

The selection of this cam in the control unit 51 is based on the characteristics shown in FIG. 5, and when the required torque and rotational speed are in the area of the first cam 21 which is a fuel-efficient cam, this cam is used. When the accelerator opening increases and the required torque goes out of the area of the fuel consumption cam and moves to the area of the second cam 22, which is a low-speed output cam, for example, the fuel-saving cam is switched to the low-speed output cam, and the rotation speed is changed. Rises from low to high rpm,
It is switched to the third cam 23 which is a high-speed output cam.

For this reason, the control unit 51 includes a crank angle sensor 52 for detecting an engine speed and a crank angle position, and an accelerator operation amount sensor 53 for detecting an operation amount of an accelerator pedal (accelerator opening). Cam position sensor 58 for detecting cam position
When the switching of the cam is determined based on these signals as described above, the two hydraulic chambers 38 and 39 are used.
The operation of the solenoid valves 45 and 46 for switching the hydraulic pressure to the pressure is controlled.

That is, when one of the solenoid valves 45 is opened by the output of the switching signal, the pressure oil from the oil pump is led to the hydraulic chamber 38 to operate the second cam 22, and the other solenoid valve 46 is opened. This time, pressurized oil is guided to the hydraulic chamber 39 in order to operate the third cam 23.

The one-way clutch provided in the automatic transmission transmits the driving force from the engine to the driving wheels, but the reverse driving force from the driving wheels does not transmit to the engine because the one-way clutch idles and does not transmit the engine braking. The engine brake cannot be activated even when the driving conditions are such that the driver wants to operate. For example, in FIG. 7, since the output shaft 71 of the automatic transmission is connected to the planetary carrier 72, the reverse driving force is transmitted to the input shaft 75 via the sun gear 74 if the internal gear 73 is fixed. . However, when the output shaft 71 rotates in the direction of driving the input shaft 75 due to deceleration, the one-way clutch 76 idles, so that the internal gear 73 is not fixed, and therefore, the reverse driving force from the output shaft 71 is It cannot be transmitted to 75.

At this time, when the overrun clutch 77 provided between the transmission elements before and after the one-way clutch is engaged, the internal gear 73 is fixed without passing through the one-way clutch 76, and the reverse driving force is transmitted to the input shaft 75. And the engine brake can be applied.

FIG. 8 shows that the overrun clutch 77 is engaged,
This is a hydraulic circuit for releasing. When the overrun clutch solenoid 62 is in the ON state by a signal from the control unit 51, the drain circuit is closed,
The pilot hydraulic pressure acts on one end (the lower end face in the figure) of the overrun clutch control valve 83 via the shuttle shift valve 82, and the valve is pushed up against the force of the spring. At this time, the line pressure is not supplied to the overrun clutch reducing valve 84, and the overrun clutch 77 is in the released state.

When the overrun clutch solenoid 62 is turned off from this state, the drain circuit is opened, and the pilot oil pressure does not act on one end of the overrun clutch control valve 83. As a result, the line pressure is reduced to the overrun clutch control valve 8.
3. It is supplied to the overrun clutch 77 via the overrun clutch reducing valve 84, and the overrun clutch 77 is engaged.

Thus, the control unit 51
Then, when it becomes a condition to apply the engine brake, the overrun clutch 77 is engaged to prevent the one-way clutch 76 from idling.

The condition for applying the engine brake (the condition for engaging the overrun clutch) is the position of the select lever (detected by the inhibitor switch 59).
Is determined in advance according to the accelerator opening and the like. For example, the 2-range gear position 2 _first speed, when the accelerator opening is less than a predetermined value at 2 _second speed, also 1 ₁ speed is the gear position irrespective of the accelerator opening is 1 range, when in the 1 _second speed is there.

On the other hand, the overrun clutch 77 is supplied with a line pressure adjusted by the overrun clutch reducing valve 84 based on the accumulator control oil pressure as an operating oil pressure. Here, the engagement force of the overrun clutch 77 increases as the accumulation control oil pressure increases. That is, by changing the accumulation control oil pressure, the overrun clutch 7
7 is increased or decreased.

The overrun clutch 77 is a wet-type multi-plate clutch, and the strength with which the clutch plate and the clutch disk are pressed against each other changes according to the operating oil pressure applied to the clutch piston.

FIG. 9 shows a hydraulic circuit for changing the accumulation control hydraulic pressure.

In the line pressure solenoid 63 which repeats ON and OFF at a constant cycle (for example, 0.02 second cycle),
In order to supply the pilot oil pressure by closing the drain circuit in the OFF state and open the drain circuit in the ON state to release the pilot oil pressure, the throttle pressure (the pilot pressure is changed to the line pressure solenoid as the OFF time ratio (duty ratio) in a certain cycle increases. 63).

The accumulation control valve 85 which receives the throttle pressure combines the throttle pressure and the line pressure to generate an accumulation control oil pressure. The higher the throttle pressure, the higher the accumulation control oil pressure.

As described above, if the duty ratio given to the line pressure solenoid 63 is reduced, the operating oil pressure to the overrun clutch 77 is reduced and the fastening force can be reduced, and if the duty ratio is increased, the operating oil pressure is increased. And the engagement force of the overrun clutch can be increased.

Incidentally, how much engine braking is required is originally determined by the relationship with the engine output. By engaging the overrun clutch with a certain strength for deceleration, an appropriate engine braking is required. Even if is operated, if the cam is switched to a cam on the side where the engine output is reduced due to a decrease in engine rotation, the engine brake suddenly works large from the middle and the driving feeling deteriorates.

To cope with this, the control unit 51 reduces the duty ratio to the line pressure solenoid 63 in synchronization with the cam switching so that the deceleration obtained by the engine brake does not change before and after the cam switching. I have to.

As shown in FIG. 10, when the overrun clutch is engaged, it is checked which cam is being used (steps 2 and 3), and a map of the duty ratio for the cam being used is selected (step 2). Steps 4-6). From the selected map, a duty ratio corresponding to the vehicle speed at that time detected by the vehicle speed sensor 60 is determined, and the line pressure solenoid 63 is ON / OFF controlled with this duty ratio (steps 7 and 8).

The switching control of the cam so as to be operated by the cam according to the operating conditions and the engagement and release of the overrun clutch are executed by another program.

In order to synchronize the switching of the cam with the decrease in the overrun clutch engagement force in the actual control, the engagement force of the overrun clutch is actually reduced after the duty ratio to the line pressure solenoid is reduced. It must be taken into account that there is a response delay of the hydraulic pressure before the change of the cam and that there is a response delay after the switching of the cam is determined until the cam is actually switched.

FIG. 11 shows the map of the duty ratio according to the vehicle speed. FIG. 11A shows the map for the fuel-efficient cam, FIG. 11B shows the map for the low-speed output cam, and FIG. 11C shows the map for the high-speed output cam. For the same vehicle speed, the low-speed output cam has a duty ratio smaller than that of the high-speed output cam than the high-speed output cam. That is, at the same vehicle speed, the lower the output cam, the lower the operating oil pressure, and the weaker the overrun clutch engagement force.

The duty ratio of the same cam is set so that the engine brake works only slowly when the vehicle speed is low, and the engine brake works well when the vehicle speed increases.

These characteristics of the duty ratio are obtained in advance by experiments.

Here, the operation of this example will be described.

Assume that the engine is driven by the high-speed output cam and the vehicle is running at high speed. In order to decelerate from this state, when the driver puts the select lever into the range 2 from the D range and releases the accelerator pedal, the overrun clutch 77 is engaged, and the engine brake operates.

On the other hand, when the engine speed is reduced by releasing the accelerator pedal, and the cam is switched to the low-speed output cam while the overrun clutch is engaged, the duty ratio map is accordingly changed for the low-speed output cam. In the map after this switching, the duty ratio is made smaller than that for the high-speed output cam even at the same vehicle speed, so that the engaging force of the overrun clutch is weakened, and the reverse driving force transmitted from the drive wheels to the engine is reduced. To be.

When the driving force of the engine becomes relatively smaller than the reverse driving force transmitted from the driving wheels to the engine due to the cam switching during the engagement of the overrun clutch, the load on the engine increases and the engine brake suddenly increases. Therefore, by reducing the reverse driving force by weakening the overrun clutch engagement force so as not to cause such a situation, the relationship between the reverse driving force and the engine driving force can be kept almost the same as before the cam switching. is there.

As a result, the deceleration obtained by the engine brake does not change discontinuously before and after the cam switching, and the same operating feeling as that of the engine driven by only one cam can be obtained. Further, unnecessary operations such as stepping on the accelerator pedal in response to sudden large engine braking during deceleration can be avoided.

Finally, the correspondence between the flowchart and FIG. 1 is shown.
8. Steps 4 to 8 fulfill the function of the fastening force weakening means 99.

According to the present invention, when the cam is switched to the low-output side cam during engagement of the overrun clutch, the operating oil pressure to the overrun clutch engagement mechanism is controlled in synchronization with the cam switching to change the driving system to the engine. Transmission to the side
Since the power is reduced, the deceleration obtained by the engine brake is prevented from changing discontinuously before and after the cam switching, and the same driving feeling as an engine driven by only one cam can be obtained. At the same time, it is not necessary to perform an operation of depressing the accelerator pedal in response to a sudden large engine brake during deceleration. Also, in the present invention,
The reverse driving force transmitted to the engine via the
Control so that the lower the vehicle speed, the lower the speed
The engine speed more appropriately according to the vehicle speed at the time of cam switching.
Rake can be suppressed and the feeling of deceleration when switching cams can be improved.
Can be smoothed.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a plan view showing an embodiment of the present invention.

FIG. 3 is a sectional view taken along line XX of FIG. 2;

FIG. 4 is a characteristic diagram of a valve lift.

FIG. 5 is a characteristic diagram of a fully open output when each cam is used.

FIG. 6 is a configuration diagram of a control system.

FIG. 7 is a diagram for explaining power transmission by an overrun clutch.

FIG. 8 is a hydraulic circuit diagram for controlling release and engagement of the overrun clutch.

FIG. 9 is a hydraulic circuit diagram for controlling the accumulation control hydraulic pressure.

FIG. 10 is a flowchart showing a control operation executed by the control unit.

FIG. 11 is a characteristic diagram showing a map of a duty ratio with respect to a vehicle speed.

[Explanation of symbols]

21 First cam (fuel-saving cam) 22 Second cam (low-speed output cam) 23 Third cam (high-speed output cam) 24 Intake / exhaust valve 25 Main rocker arm 28, 29 Sub rocker arm 45, 46 Solenoid valve 51 Control Unit 52 Crank angle sensor (engine speed sensor) 53 Accelerator operation amount sensor 54 Throttle opening sensor 58 Cam position sensor 59 Inhibitor switch (select lever position sensor) 60 Vehicle speed sensor 61 Automatic transmission 62 Overrun clutch solenoid 63 Line pressure solenoid 76 One-way clutch 77 Overrun clutch 85 Accumulation control valve 91 One-way clutch 92 Overrun clutch 93 Engagement condition determination means 94 Overrun clutch engagement mechanism 95 Cam 96 Beam switching determination unit 97 cam switching mechanism 98 lower output cam switching determination section 99 engaging force weakening means

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B60K 41/00-41/28 F02D 13/00-13/04 F02D 29/00-29/06 F16H 61/00-63 / 48

Claims (3)

(57) [Claims] A one-way clutch that transmits driving force from the engine to driving wheels but does not transmit reverse driving force from the driving wheels to the engine, and a transmission element in front of and behind the one-way clutch in response to operating hydraulic pressure. An overrun clutch to be disengaged, means for determining from the operating conditions whether or not the engagement condition of the overrun clutch has been satisfied, and an overrun clutch for supplying operating hydraulic pressure to engage the overrun clutch when the engagement condition has been satisfied. A plurality of cams having cam profiles having different output characteristics, a means for determining whether or not to switch these cams according to operating conditions, and an automatic transmission having a clutch engagement mechanism. A cam switching mechanism for selectively switching these cams and transmitting the movement of the cams to at least one of the intake and exhaust valves; Means for determining whether the overrun clutch is being engaged and whether the cam can be switched to a low-output cam, and in synchronization with the low-output cam switching. By weakening the overrun clutch, the
Means for reducing the reverse driving force transmitted to the engine. 2. Transmission of driving force from an engine to driving wheels.
But does not transmit the reverse driving force from the drive wheels to the engine.
This one-way responds to the way clutch and hydraulic pressure.
Overlay for engaging and releasing the transmission elements before and after the clutch
Clutch and the engagement conditions of this overrun clutch.
Means to determine from the operating conditions whether or not
Overrun by supplying hydraulic pressure when the conditions are met
An overrun clutch fastening mechanism for engaging the clutch
Automatic transmission with different output characteristics.
Multiple cams with different profiles and switching between these cams
Means for determining whether or not to obtain
If these cams are selectively switched according to the judgment result,
The movement of this cam is transmitted to at least one of the intake and exhaust valves.
Engine output control device with a cam switching mechanism
Operating fluid to the overrun clutch fastening mechanism.
Form a circuit that controls pressure independently, and
-The cam output is low while the burrun clutch is engaged.
Means for determining whether the cam can be switched to the side cam.
The overrun clutch is synchronized with the low output cam changeover.
Only the operating oil pressure to the
To weak fastening force of the pitch, transmitted from the drive wheels to the engine
Means for controlling the reverse driving force to be reduced.
An engine output control device that specializes in 3. The overrun clutch is operated after the cam is switched.
The lower the vehicle speed, the lower the fastening force,
Control to reduce the reverse driving force transmitted from the engine to the engine.
What is claimed in claim 1 or claim 2
An output control device for an engine according to any one of the claims.