JPH0472968B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device capable of performing multi-stage valve timing control according to engine operating conditions.

There are various types of variable valve timing mechanisms, such as one proposed by the present applicant in which a pair of slits are provided adjacent to an inner sleeve on the camshaft side and an outer sleeve on the timing pulley side. The pair of slits extend in directions that are inclined to each other, and a roller bearing is installed within the slits. The roller bearing is supported by a cylindrical moving body that is movable in the camshaft direction.
The rotary drive motor is connected to the movable body through a rotary-linear motion conversion means comprising a threaded portion on its output shaft and a nut engaged with the threaded portion. Depending on the direction of rotation of the motor controlled by the control circuit, the roller bearing moves in the direction of the camshaft within the intersecting slits, causing relative rotation of the pair of sleeves. As a result, the valve timing changes in two stages between the maximum rotational position of the motor in one direction and the maximum rotational position in the other direction.

If equipped with a variable valve timing mechanism,
Valve timing is not constant and should change depending on the operating condition of the engine. That is, the variable valve timing mechanism is equipped with an electric drive means such as a step motor that receives a control signal from a control circuit, and the step motor controls the valve timing to a desired valve timing based on the valve timing control signal from the control circuit. . At the time of starting, there is an optimum valve timing to ensure good starting performance, and if this valve timing is not achieved at the time of starting, the control circuit applies a drive signal to the step motor in order to obtain the optimum valve timing for starting. . However, the starter sometimes rotates during startup, and the electrical load on the starter is extremely large, so if the starter is added to drive the step motor to control valve timing, malfunctions may occur due to insufficient battery power. There is a possibility that this may occur. The present invention aims to eliminate this drawback.

A valve timing control device for an internal combustion engine according to the present invention includes a variable valve timing mechanism and a control circuit, and the variable valve timing mechanism includes an electric drive means that receives a control signal from the control circuit, and an electric drive means that receives a control signal from the control circuit. A transmission means that is connected to each other to obtain a linear motion in a direction parallel to the axis of the camshaft, and a rotating driven member that is connected to the transmission means and is rotatably provided coaxially with the camshaft and is connected to the crankshaft. , a relative angle control means for controlling valve timing as a relative angular position with respect to the camshaft, and in response to a control signal from the control circuit, the electric drive means controls the valve timing by the relative angle control means via the transmission means. The control circuit controls the timing in multiple stages, and the control circuit includes: means for forming a control signal to be supplied to the electric drive means for obtaining valve timing according to the operating conditions of the engine, and when the electric drive means is activated. means for detecting whether the engine is rotating; means for detecting whether the engine is rotating; and means for detecting whether the engine is rotating; comprising means for prohibiting operation;
It is characterized by

According to the present invention, the starter is allowed to perform its normal operation unless controlled to change the valve timing. On the other hand, when the valve timing is being controlled to change, the starter is prohibited from operating, and once the valve timing has been controlled, the starter is allowed to operate.

Referring to the accompanying drawings, 1 is a cylinder block, 2 is a cylinder head, 3 is a cylinder head cover, 4 is an intake pipe, 6 is a throttle valve,
8 is an exhaust pipe. 10 is a crankshaft connected to a piston 14 via a connecting rod 12. A cam 20 is formed on the camshaft 18, and the cam 20 is connected to the intake valve 2 via rocker arms 22 and 23.
4. Acts on the exhaust valve 25 against the valve spring 26. A timing pulley 28 as a rotationally driven member is positioned at one end of the camshaft 18 so as to be relatively rotatable, and is wound around a pulley 32 on the crankshaft 10 via a timing belt 30. The timing pulley 28 and the camshaft 18 are connected by a variable valve timing mechanism 34 according to the present invention.

The configuration of the variable valve timing mechanism 34 is shown in FIG. Variable valve timing mechanism 34
According to the present invention, an electric drive means receives a control signal from a control circuit 60, which will be described later, and a transmission means connected to the electric drive means to obtain linear motion in a direction parallel to the axis of the camshaft. , valve timing as a relative angular position with respect to the camshaft of a rotary driven member (timing pulley 28 in the embodiment) connected to the transmission means and rotatably provided coaxially with the camshaft and connected to the crankshaft; and relative angle control means for controlling the angle. First, the relative angle control means will be explained. An inner sleeve 36 is fixed to one end of the camshaft 18 with a bolt 37. The timing pulley 28 is mounted on this inner sleeve 36 by a bearing 39. An outer sleeve 38 extends integrally from the boss portion of the timing pulley 28 so as to be coaxial with the inner sleeve 36. The inner sleep 36 and the outer sleep 38 have adjacent slits 40 and 42. As shown in FIG. 3, one of them 40 is straight, while the other 42 is slanted, so that they cross each other. Slits 40 and 4
Bearings 44 and 46 are located within 2, respectively. The bearings 44 and 46 are supported on a shaft portion 48' that integrally extends in the radial direction from a cylindrical moving body 48 that reciprocates along the direction of the camshaft.
In the above embodiment, the inner sleeve 36, bolt 37, bearing 39, outer sleeve 38, slits 40, 42, bearings 44, 46, and moving body 48 constitute the relative angle control means of the present invention.

Reference numeral 50 denotes a step motor as an electric drive means, which is connected to the movable body 48 via a transmission means. The transmission means is constructed as a so-called recirculating ball screw. That is, the motor 50
An external thread is cut on the output shaft 50' of the
has endless internal threads, and a ball 54 is located between these threads. A guide rod 51 extending from the housing of the motor 50 is fitted into a camshaft guide groove 52' formed in the nut 52.
With this structure, the output shaft 50' of the motor 50
It will be clear that the rotational movement of the nut 52 is converted into a linear movement of the nut 52. The nut 52 is connected to the movable body 48 via a bearing 55, and the bearings 44 and 46 are driven in the camshaft direction.

Reference numeral 56 denotes a case, one end of which is fixed to the hub portion of the timing pulley 28 by a bolt 57, and the other end rotatably connected to the motor housing by a bearing 58. 59 is a timing belt cover, which houses the timing belt 30 including the variable valve timing mechanism 34 of the present invention.

The rotation of the crankshaft 10 is controlled by the timing pulley 3.
2. It is transmitted to the timing pulley 28 via the timing belt 30. The rotation of the timing pulley 28 is transmitted to the shaft portion 48' via a roller bearing 46 located within a slit 42 of an outer sleeve 38 integral with the timing pulley 28. The rotation of the shaft portion 48' is transmitted to the inner sleeve 36 from the roller bearing 44 located in the slit 40, and the rotation of the cam shaft 1 is transmitted to the inner sleeve 36.
8 is rotationally driven. When the cam 20 on the camshaft 18 reaches the peak, it pushes the stems of the valves 24, 25 via the rocker arms 22, 23, and opens the valves 24, 25 against the valve spring 26.

When the step motor 50 is driven, its output shaft 50' rotates and the nut 52 moves in the direction A or B in FIG. Therefore, the roller bearing 44 provided on the shaft of the movable body 48 that moves together with the nut 52
and 46 also have respective slits 40 and 42 in the same direction.
move within. Since the slits 40 and 42 cross each other as shown in FIG.
The linear motion in the camshaft direction is converted into relative rotation between the inner sleeve 36 and the outer sleeve 38 in the direction C or D in FIG. 3. Therefore,
Outer sleeve 38 on the driving side of the camshaft 18 connected to inner sleeve 36 on the driven side
That is, the timing pulley 28 and the crankshaft 10
The phase relative to changes. Therefore, valve 2
The valve timing, which is the crank angle position when the cam 20 acts on the valves 4 and 25, is variable. The valve timing is determined according to the position of the movable body 48 in the camshaft direction, in other words, according to the rotation angle of the step motor 50 from the reference position.

It is clear that with the above structure, it is possible to obtain valve timing that changes continuously according to the rotation of the motor 50, but the present invention focuses on this and changes the rotation angle of the step motor according to the engine operating conditions. We are trying to control valve timing in multiple stages, and the principle is as follows. In other words, valve timing depends on engine operating conditions,
For example, it is determined by the water temperature THW, etc., and the step motor 5
0 is controlled so that the valve timing corresponds to these operating conditions. However, if this control is performed also when turning the starter during startup, a step-out may occur because the starter consumes a large amount of current. Therefore, the present invention has a mechanism that detects whether the step motor is on or off and prohibits the starter from operating while the step motor is operating. below,
The configuration for realizing the operation of the present invention in this manner will be described.

A control circuit 60 performs valve timing control according to the present invention by driving the variable valve timing mechanism 34, and has a function as a microcomputer. Signals from various operating condition detection sensor groups are input to the control circuit 60. The intake pipe pressure sensor 62 is provided in the intake pipe 4 and detects the intake pipe pressure Pb. The rotation speed sensor 64 generates a pulse signal depending on the position of a detection piece 64' provided on the crankshaft. Further, a water temperature sensor 66 is provided at the cylinder block 1 to detect the cooling water temperature.

The control circuit 60 includes these sensor groups 62, 64,
The signal from 66 is processed to form a drive signal for step motor 50.

FIG. 4 schematically shows the control circuit 60 as a block diagram. The input port 68 is connected to an intake pipe pressure sensor 62, a rotation speed sensor 64, and a water temperature sensor 6.
Receives signal from 6. The output port 70 is connected to the stator coil of the step motor 50 by turning a latch circuit 72 and a gate 74. The step motor 50 has a plurality of excitation coils, and rotates in a predetermined direction step by step by sequentially selecting the excitation coils to be magnetized. The gate 74 has the role of selecting a part of the excitation coils to be magnetized from among the plurality of excitation coils. The latch circuit 72 also receives commands from the microcomputer regarding the direction in which the step motor should rotate and the number of steps to rotate, and has the role of outputting an opening/closing command for the gate 74 in accordance with a predetermined sequence to execute the commands. The detailed structure of the step motor 50 is not related to the characteristics of the present invention, so it will not be described in detail here, but if necessary, please refer to Japanese Patent Application No. Please refer to the description and drawings attached to the application (see Publication No. 57-124047).

90 is an ignition switch, which has a starting contact 90-1 and a starter contact 90-2. Start contact 90-1 is connected to input port 68, and starter contact 90-2 is connected to contact 92-1 of relay 92.
It is connected to the starter 94 via. One end of the coil 92-2 of the relay 92 is connected to the output port 70, and the other end is connected to the battery B.

94 is a relay for controlling the operation of the control circuit, its contact 94-1 is connected to the input port 68, and its operating coil 94-2 is connected to the output port 7.
Wired to 0.

Input/output ports 68 and 70 are connected by bus 80 to microprocessing unit 82, which is a component of a microcomputer system.
(MPU), read-only memory 84 (ROM), and random access memory 86 (RAM). 88 is a clock signal generator (CLOCK). The ROM 84 stores a routine in the form of a program that implements the valve timing switching control of the present invention as outlined above. MPU82
performs valve timing control according to the stored contents of the ROM 84. This program is the fifth
The flowchart is shown in the figure as a flowchart, and this flowchart will be explained step by step below.

In FIG. 5, 100 indicates the start of this routine, which is an interrupt routine executed at predetermined time intervals. When the MPU 82 receives an interrupt request for this time, this interrupt routine starts executing, and at 101 the MPU
looks at a predetermined area of RAM 86 and determines whether contact 90-1 of ignition switch 90 is ON or not. If Yes, go to 102 and also RAM
It is determined whether the step motor 50 is on or not, which is stored in a predetermined area 86.
If Yes, that is, if it is recognized that the step motor is in operation, the process goes to 104, where it is determined whether the rotational speed Ne detected by the engine rotational speed sensor 64 is 0 or not.
If Yes, it is determined that the engine is stopped and the process goes to 106. MPU82 is coil 92-2 of relay 92
Turn off the output port leading to coil 9.
2-2 is not energized, contact 92-1 is open, and starter 94 is not driven even if the starter contact 90-2 is turned.

If it is determined in step 102 that the step motor is not on, the process branches to No, and it is determined whether the rotational speed Ne is 0 or not. If Ne=0 (Yes), it is considered that it is okay to drive the starter, and the process goes to step 108. MPU82
turns on the output port leading to the coil 92-2 of the relay 92, energizes the coil 92-2, and closes the contact 9.
2-1 can be closed and the starter 94 can be driven.

When the starter 94 is turned and the engine starts, 1
The determination at step 06 is No, and when step 110 is reached, normal step motor control is performed in which the valve timing is controlled according to the signals from each sensor, as described above.

After that, when the engine stops, the ignition switch is turned OFF. Therefore, the branch to No is 10
1, and initialization processing is performed at 120. The content of this process is to set the valve timing to the most delayed valve timing. After the initialization process is completed, a command to turn off the control relay is issued from the output port 70. At this time, the coil 94-2 of the relay 94 is demagnetized and the contact 94-1 is opened.

As described above, in the present invention, malfunction of the valve timing control device can be prevented by prohibiting the starter from operating when the step motor is driven.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic diagram of an internal combustion engine according to the present invention;
Fig. 2 is a detailed sectional view of the variable valve timing mechanism in the camshaft direction, Fig. 3 is a view taken in the direction of the arrows in Fig. 2, Fig. 4 is a block diagram of the control circuit, and Fig. 5 shows the software configuration of the present invention. Flowchart diagram showing 10... crankshaft, 18... camshaft, 24...
...Intake valve, 25...Exhaust valve, 34...Variable valve timing mechanism, 36...Inner sleeve, 38
...Outer sleeve, 40, 42...Slit,
44, 46... Roller bearing, 50... Step motor, 60... Control circuit, 62... Pressure sensor, 64... Rotation speed sensor, 66... Water temperature sensor.

Claims (1)

[Claims] 1. Consisting of a variable valve timing mechanism and a control circuit, the variable valve timing mechanism includes an electric drive means that receives a control signal from the control circuit, and a camshaft connected to the electric drive means. a transmission means that obtains linear motion in a direction parallel to the axis of the transmission means, and a rotating driven member connected to the transmission means and rotatably provided coaxially with the camshaft, and connected to the crankshaft relative to the camshaft. and a relative angle control means for controlling valve timing as an angular position, and the electric drive means controls the valve timing by the relative angle control means in multiple stages via the transmission means in response to a control signal from the control circuit. and the control circuit includes: means for forming a signal to be supplied to the electric drive means for obtaining valve timing according to the operating conditions of the engine; and means for determining whether the electric drive means is operating. means for detecting whether the engine is rotating; and means for inhibiting operation of the starter when the electric drive means is operating to control valve timing and the engine is not rotating. Consisting of
A valve timing control device for an internal combustion engine, characterized in that: