JPH0367009A - How to control the engine - Google Patents

Abstract

PURPOSE:To enable continuous operation always without obstruction by changing over and fixing the operating characteristics of another without valve capable of being changed over even though part of a valve with possibility of changing over its operating characteristics is fixed to the operation in the applicable operating characteristics due to malfunction of a valve operating characteristics changeover mechanism. CONSTITUTION:Assuming that a coupling changeover means 21a makes malfunc tion, other normally operating coupling changeover means 21b, 21c, 21d are put in coupling disengaged condition and fixed if the first named means is fixed to the low speed valve operation characteristics LVT. Thus, all valves can be operated in the low speed valve operating characteristics. This is trans ferred to the high torque side valve operating characteristics when the number of revolutions Ne<N1, where N1 is specified number of engine revolutions, and turned into the low torque side valve operating characteristics when Ne>Nl. Thus the transmission concerned is controlled with a control map selected, which corresponds to the engine output in the condition that the high torque side valve operating characteristics are used while Ne<N1.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to engine control in which valve operating characteristics can be freely changed.

Note that switching the valve operating characteristics refers to switching at least one of the opening/closing timing, opening period, and valve lift amount of an intake valve or exhaust valve, and refers to switching at least one of the opening/closing timing, opening period, and valve lift amount of the intake valve or exhaust valve. It also includes reducing the open period of the valve to substantially zero and switching it to a closed state.

(Prior art) An engine in which the valve operating characteristics of both or one of the intake valve and exhaust valve can be freely switched between a low-speed valve operating characteristic suitable for a low-speed range and a high-speed valve operating characteristic suitable for a high-speed range. is disclosed in Japanese Patent Publication No. 49-33289, but in this one, the low-speed valve operation characteristic is changed in the region where the engine speed is below a predetermined value and the intake negative pressure is below a predetermined value (vacuum side). In other areas, it switches to high-speed valve operation characteristics.

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 N1, and in the region of engine rotation speed Ne - NI, the torque of the low-speed valve operation characteristic (line At) is thicker than the torque of the high-speed valve operation characteristic (line Bt), In the region where Ne>Nt, 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 A1 and A2) are referred to as high-torque side valve operating characteristics, and the characteristics with smaller torque (characteristics shown by lines B1 and B2) are referred to as low-torque side valve operating characteristics. This is called the operating characteristic.

(Problem to be Solved by the Invention) In such an engine, some of the valves whose valve operating characteristics can be freely switched may be switched between high-speed valve operating characteristics and low-speed valve operating characteristics due to malfunction of the valve operating characteristic switching mechanism. If the operation is fixed to one of the valve operating characteristics, the following problems will occur.

Here, the state of the engine when all the valves whose valve operating characteristics are switchable are operating with the same valve operating characteristic is referred to as the usage state of the valve operating characteristic.

Normally, the state in which the high-speed valve operating characteristic is used and the state in which the low-speed valve operating characteristic is used are switched by the rotational speed Net, and the valve is operated in a state in which the high-torque side valve operating characteristic is used and a state in which the low-torque side valve operating characteristic is used. For example, when the engine is operated with the valve operating characteristic on the low torque side, the gear change control of the transmission connected to the engine and the hydraulic pressure control of the friction element that selects the gear stage are performed on the low torque side. This is done based on a control map that is set in accordance with the engine output torque under the conditions in which the valve operating characteristics are used. In this case,
If a part of the valve whose valve operating characteristics can be freely switched as described above malfunctions and becomes fixed to the high-speed valve operating characteristic, the valve that operates normally in the high rotation range (Ne > Ns) will not be able to operate normally. A malfunctioning valve with low-speed valve operating characteristics will operate with high-speed valve operating characteristics, so the engine output torque will vary depending on whether the low-torque side valve operating characteristic is used or the high-torque side valve operating characteristic is used. The torque characteristics will be different. In other words, even though transmission control is performed based on a control map that corresponds to the engine output torque when the low-torque side valve operating characteristics are used, the actual engine output torque does not correspond to that control map. It turns out. At this time, if the actual engine output torque is larger than the engine output torque when the low-torque side valve operating characteristic is used, there is a risk that the operating oil pressure of the friction element will be insufficient and slippage will occur in this friction element. Also,
Since the shift control is performed using a shift map that does not correspond to the actual engine output torque, the shift feeling may deteriorate.

On the other hand, in order to prevent these problems, it is necessary to prepare and memorize a large number of control maps in order to control the transmission in response to various combinations of valve operating characteristics, assuming that some valves may malfunction. This is not economically desirable, such as having to do so.

In view of the above-mentioned problems, it is an object of the present invention to provide an engine control method that allows operation to continue without any problem even if a part of the valve whose valve operation characteristics can be freely switched malfunctions. It is an object.

2. Configuration of the Invention (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a structure in which the valve operating characteristics of a part of the intake valve or the exhaust valve are changed so that the valve operating characteristics can be freely changed. , when the valve operating characteristic is fixed to the valve operating characteristic 1 due to a malfunction of the valve operating characteristic switching mechanism, the valve operating characteristic of the switchable valve other than the valve fixed to the valve operating characteristic 1 is changed to the valve operating characteristic 1. The switch is fixed at the same time.

(Function) According to this control method, even if a part of the valve whose valve operating characteristics can be freely switched is fixed to operate at one valve operating characteristic due to malfunction of the valve operating characteristic switching mechanism,
Since the valve operating characteristics of the other switchable valves are switched and fixed in accordance with the fixed valve operating characteristics, the engine is operated using the fixed valve operating characteristics. In this way, since the engine is limited to operation under the conditions in which the normally selected valve operating characteristics are used, it is appropriate to select a control map that corresponds to the engine output torque under the normal valve operating characteristics in accordance with the rotational speed. This enables easy transmission control, and there is no need to prepare a control map that corresponds to various combinations of valve operating characteristics.

(Example) Preferred examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of an engine E for using the present control method, and is located close to each connection switching means (21a to 21d) of the variable valve timing/lift mechanism VT to grasp the operating state of these connection switching means. Position detection unit 101 for
is installed.

The variable valve timing/lift mechanism VT is for engine E.
The opening/closing timing, opening period, and lift amount of the intake valve of
This is a mechanism that switches between low-speed valve operating characteristics suitable for low-speed ranges and high-speed valve operating characteristics suitable for high-speed ranges.
This switching is performed by turning on/off the switching valve 91 as described later.
This is done by supplying and discharging a predetermined hydraulic pressure by turning off. The switching valve 91 is turned off and on by a switching signal VTS from the control unit CU, and this switching signal VTS is output based on the position signal from the position detection section 101.

Next, 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 la and 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 provided in 3. The first cam 3' is pivotally supported by a second low-speed cam 3', a high-speed cam 5, and a rocker shaft 6 parallel to the camshaft 2. 2nd and 3rd
It is opened and closed by the action of the 0-tsuka arm 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 la and lb. 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 6, 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 intake valve 1a, 1b is biased toward the valve closing direction, that is, upward, by a valve spring 1f3.17.

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 la from the rocker shaft 6.
, is slightly extended to the lb 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 which is 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 9.8 are connected. 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 performed by hydraulic pressure supplied into the hydraulic chamber 29 through the oil passages 31.degree. 32.30 in response to the operation of the switching valve 91.

Incidentally, such a variable valve timing/lift mechanism is disclosed in detail in, for example, Japanese Patent Laid-Open No. 82-121811.

Next, the variable valve timing
The operation of the lift mechanism VT will be explained.

When engine E is operating at low speed, the switching valve 91 is turned OFF.
As shown in FIG. 3, the communication between the oil passage 31 and the oil pressure source (not shown) is cut off, and oil pressure is not supplied to the oil pressure chamber 29 of the connection switching means 21, and the stopper 24 is closed to the spring 25. is pressed toward the 30th lug arm 9 side. 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 Ia and Ib are opened and closed by the first and second low-speed cams 3 and 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 1a*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.
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 the engine E is operated at high speed, the switching valve 91 is
As shown in FIG. 4, a hydraulic pressure source (not shown) and the oil passage 31 are communicated with each other by a switching 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 moves, and the first piston 22 causes the first and third pistons to move.
The 0th lever arm 7.9 is connected, and the 3rd and 20th lever arms 9, 8 are connected by the second piston 23.

In this way, 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 pulps fa and fb are fed 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 valve 1allb 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 cam 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. In this figure, the low-speed valve operating characteristics in use are shown as lines.
High-speed valve operating characteristics Line H shows the characteristics under use. As mentioned above, both characteristics intersect at the engine speed NI, and in the region of engine speed N e < NI, the torque of the low-speed valve operation characteristic (line At) is higher than the torque of the high-speed valve operation characteristic (line B). , ) larger than , N e >
In the region of N t, the torque of the high-speed valve actuation characteristic (line A
2) is larger than the torque of the low-speed valve operation characteristic (line B2).

The present applicant has disclosed a method for detecting malfunctioning state of the connection switching means 21 as described above in Japanese Patent Application Laid-Open No. 63-1479.
There is a device disclosed in Japanese Patent No. 09, which is referred to herein as a valve operating characteristic switching individual abnormality detection system.

An example of this valve operating characteristic switching individual abnormality detection system is shown in FIG. As shown in Figure 1, the connection switching means (
A position sensor 40 that detects the positions of the pistons (22, 23) and the stopper 24 is attached to the position detection unit 101 provided for each of the pistons 21a to 21d). In this valve operating characteristic switching individual abnormality detection system, for example,
When the pistons (22, 23) and the stopper 24 are in the disconnected state as shown in FIG. 3 even though the switching valve 91 is in the open state and the hydraulic pressure is applied to the oil passage 31, Based on a signal from the position sensor 40 indicating this state, the control unit CU determines that a malfunction has occurred in a part of the variable valve operating characteristic switching mechanism VT.

Next, a control method according to the present invention will be explained based on the control flow shown in FIG.

First, in step S1, when a signal from the valve operation characteristic switching individual abnormality detection system indicating malfunction of one of the connection switching means is detected, in step S2,
Fixed valve operating characteristics are low speed valve operating characteristics LVT
or high-speed valve operating characteristics HVT. The connection switching means 21 in FIG.
If this is fixed to the low speed valve operating characteristic LVT, the process proceeds to step S3 and other normally operating connection switching means (2l b, 21 c, 21 d) are selected.
are fixed in the uncoupled state as shown in Fig. 3. In this way, all valves can be operated with slow valve actuation characteristics. As shown in Fig. 6, the low-speed valve operating characteristics are high-torque valve operating characteristics when the rotational speed Ne<Nt, and low-torque valve operating characteristics when Ne>N I, so the transmission has N13. When <Nl, the control map is selected and used that corresponds to the engine output torque when the high-torque side valve operating characteristic is used, and when Ne>N1, the engine output torque is controlled when the low-torque side valve operating characteristic is used. It is controlled using a selected control map corresponding to the

On the other hand, if it is determined in step S2 that the malfunctioning connection switching means 21a is fixed to the high-speed valve operating characteristic HVT, the process proceeds to step S4, in which other normally operating connection switching means (21b, 21 c, 21
By fixing d) in the connected state as shown in FIG. 4, all valves are operated with high speed valve actuation characteristics. In this case, the transmission has a rotational speed N as shown in FIG.
e When <N, the control is performed based on the control map that corresponds to the engine output torque when the low-torque side valve operating characteristic is used, and when Ne>N, it corresponds to the engine output torque when the high-torque side valve operating characteristic is used. control based on the control map.

In this way, in this control method, the connection switching means (21a to
Even if some of the valves whose operating characteristics can be freely switched are fixed to the low-speed valve operating characteristics or the high-speed valve operating characteristics due to malfunction of some of the valves described in 21d), the valve operating characteristics of other switchable valves may not be fixed. Since the valve operating characteristics are switched to and fixed, the engine operates using the fixed valve operating characteristics. In this way, the engine is limited to operation using the normally selected high-torque side valve operating characteristic or low-torque side valve operating characteristic. Appropriate transmission control can be achieved by selecting a control map that corresponds to the engine output torque under use, and there is no need to prepare control maps that correspond to various combinations of valve operating characteristics.

Effects of the Invention According to this control method, even if a part of the valve whose valve operating characteristics can be freely switched is fixed to operate at one valve operating characteristic due to malfunction of the valve operating characteristic switching mechanism,
Since the pulp operating characteristics of the other switchable valves are switched and fixed in accordance with the fixed valve operating characteristics, the engine will be operated using the fixed valve operating characteristics. In this way, since the engine is limited to operation under conditions in which the normally selected valve operating characteristics are used, by selecting a control map corresponding to the engine output torque under the normal valve operating characteristics in accordance with the rotational speed, Appropriate transmission control without friction element slippage or shift lock can be achieved, and a control map corresponding to various combinations of pulp operating characteristics is not required, which is economically advantageous.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of an engine for using the control method according to the present invention; FIGS. 2, 3, and 4 are sectional views showing the variable valve timing/lift mechanism of the engine; Figures 5A and 5B are graphs showing the relationship between the valve timing and lift amount of the variable valve timing/lift mechanism, and Figure 6 is a graph showing the relationship between the engine output torque and engine speed due to the variable valve timing/lift mechanism. FIG. 7 is a graph showing the relationship; FIG. 7 is a sectional view showing the configuration of the valve operating characteristic individual abnormality detection system; FIG. 8 is a control flow of the engine control method described above. 1a+1b...Intake valve 3.3'...Low speed valve 5...High speed valve 2
1a to 21d...Connection switching means 40...Position sensor 91...Switching valve Fig. 1

Claims (1)

[Scope of Claims] 1) In an engine in which the valve operating characteristic of at least one of an intake valve and an exhaust valve is switchable, a portion of the intake valve or the exhaust valve whose valve operating characteristic is switchable is configured to control the valve operation. When operation is fixed at the valve operating characteristic 1 due to malfunction of the characteristic switching mechanism, all the valve operating characteristics of other valves whose valve operating characteristics are switchable are switched and fixed to the valve operating characteristic 1. An engine control method characterized by: