JPH0353460B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for an internal combustion engine that switches valve timing by changing the rotational phase of a crankshaft and a camshaft.

It is known that the valve timing is changed by changing the phase between the crankshaft and the camshaft. In this case, a drive means is provided between the crankshaft and the camshaft to rotate the camshaft relative to the crankshaft, and the position of the crankshaft when the cam on the camshaft contacts the push rod, that is, the valve timing. is controlled. Internal combustion engines equipped with this type of valve timing control device have a problem in that ignition timing is out of order due to valve timing control. That is, in a typical engine, the camshaft is also connected to the distributor shaft, and a crank angle sensor is provided on the distributor shaft to determine the top dead center position of the piston and input this information to a computer. However, due to the switching operation of the valve timing control device, the camshaft is rotated relative to the crankshaft, and a crank angle position signal that is shifted by the amount of rotation is input to the computer, causing the ignition timing to deviate from the normal calculation time. A crazy problem arises. Such a deviation in ignition timing occurs not only in internal combustion engines that are electronically controlled by a computer, but also in conventional internal combustion engines that control ignition timing using governor and bakeem characteristics. In other words, in this internal combustion engine, ignition timing is controlled by opening and closing contacts using a cam on the distributor shaft, but the camshaft is turned relative to the crankshaft when switching valve timing. As a result, the crank angle position when the cam drives the contact point deviates from the normal value.

In view of the drawbacks of the prior art, an object of the present invention is to provide a configuration that can maintain the ignition timing at a calculated value even when the valve timing is changed. In order to achieve this object, the present invention is provided with means for correcting the ignition timing by the amount of rotation of the camshaft when the valve timing is changed.

Explaining the following with reference to the drawings, in FIG. 1, 10 is a cylinder, 12 is a piston, 14 is a cylinder head, 16 is an intake valve, 18 is an exhaust valve, 2
0 is an intake port, 21 is a spark plug, 22 is an exhaust port, 24 is a crankshaft, and 25 is a connecting rod, which are well-known components of an internal combustion engine and are not directly related to the present invention. A detailed explanation of the connection relationship will be omitted.

A timing pulley 28 is attached to one end of the crankshaft 24.
is fixed, and this pulley 28 is connected via a timing belt 30 to a timing pulley 34 provided at one end of a camshaft 32. Reference numeral 36 denotes a distributor, which has a main body 38 and a distributor shaft 40.
is meshed with a gear on the camshaft 32 by a gear (not shown). A crank angle sensor 39 is provided on the main body 38 so as to be able to face a permanent magnet detection piece 41 on the distributor shaft 40 . Therefore, the crank angle sensor 39 is connected to the distributor shaft 4.
A pulse signal is generated according to the rotation of 0.

The camshaft 3 is connected to the crankshaft 24 between the timing pulley 34 on the camshaft 32 and the camshaft 32.
For example, a valve timing control device 41 as shown in FIG. 2 is provided. To explain this device 41, the camshaft 3
An inner sleeve 43 is fixed to the shaft end of No. 2 by a bolt 42. A detent pin 44 is inserted between the inner sleeve 43 and the camshaft 32 to prevent relative rotation between these members.

An outer sleeve 45 is attached to the timing pulley 34.
are integrally formed. This outer sleeve 45, ie, the timing pulley 34, is connected to the inner sleeve 43 by a bearing 47, ensuring free rotation of both.

A pair of slits 46 and 48 adjacent to each other are provided on the circumferences of the inner sleeve 43 and outer sleeve 45, which are rotatable relative to each other (see FIG. 3). As shown in Figure 3, adjacent slits 4
One of the slits 6 and 48 (that is, the slit 46) extends in the axial direction of the camshaft, while the other (that is, the slit 48) is inclined with respect to the axial direction of the camshaft. They are in a mutually inclined relationship. These slits 46, 48 can be rotated independently. Roller bearings 50 and 52 are located respectively.

A bearing support 56 is provided within the inner sleeve 43 so as to be horizontally movable in the camshaft direction. A bearing support shaft 58 extends integrally from the bearing support body 56 in the radial direction. The aforementioned roller bearings 50 and 52 are attached to the bearing support shaft 58. These sleeves 43 and 4
5. Parts such as the roller bearings 50 and 52 and the bearing support 56 are housed in a case 60. One end of this case 60 is connected to the timing pulley 34 by a bolt 62. The other end of the case 60 is supported by a motor 64.

An output shaft 74 of the motor 64 is screwed into a nut 76 and connected to the support body 56 via a bearing 78 . A guide rod 8 extending from the housing of the motor 64
0 fits into the guide groove 76A of the nut 76,
Therefore, the rotation of the output shaft 74 of the motor is controlled by the nut 76.
is converted into linear motion in the cam axis direction.

Connect the timing pulley 34 to the timing belt 30
When rotated by the crankshaft 24 through the
The outer sleeve 45 rotates together with the pulley 34 and is connected to the roller bearing 52 through the slit 48.
A rotational force about the camshaft 20 is applied to the camshaft 20 . Therefore, the bearing support body 56 rotates, and its rotational force rotates the slit 46 of the inner sleeve 40 via the shaft portion 58 and the roller bearing 50, and as a result, the inner sleeve 43 and the camshaft 32 rotate. Therefore, a predetermined valve timing is obtained, which is determined when the cam 32 on the camshaft 32 comes into contact with the push rod.

When the motor 64 is driven to control the valve timing, the rotational movement of the output shaft 74 is converted into a linear movement of the drive nut 76 by the action of the threaded portion, so that the bearing support 56 moves according to the direction of rotation of the motor 64. Move left and right. Bearing support 5
This left and right movement of 6 is transmitted to the bearings 50, 52 via the shaft portion 58, and the bearings 50, 52
moves in the direction of arrow A in FIG. 3 while rolling within the slits 46 and 48. Then slit 4
6 and 48 intersect, so the outer sleeve 4
5 and the inner sleeve 43, and as a result, the relative angular position between the crankshaft 24 and the camshaft 32 changes.

FIG. 4 is a block diagram of a control circuit showing only the portions related to the present invention of the control circuit for controlling the operation of an electronically controlled internal combustion engine. The signal from the crank angle sensor 39 is applied to the input/output port 82 along with signals from other operating state detection sensors, such as a load sensor 80 and a temperature sensor 81. The input/output port 83 is connected to the motor 64 via a motor drive circuit 84 and to the spark plug 21 via an igniter 85. These input/output ports 82 and 83 are the components of the microcomputer, such as MPU 87 and ROM 8.
8, RAM 89, clock generator 90 and bus 91
connected via. The MPU 87 controls the present invention by driving the motor 64 and the spark plug 21 according to software described later.

FIG. 5 shows a block diagram of the motor drive circuit 84 of FIG. The motor drive circuit 84 includes two pairs of PNP and NPN transistors 841, 842 and 843, 844 connected in series, the bases of the transistors 841, 842 are directly connected to the input terminal 845, and the transistor 84
The base of 3,844 is connected to an input terminal 845 via an inverter 846. transistor 84
Junction point of 1 and 842 and transistors 843 and 8
A motor 64 is connected between the junction point with 44.
If the input terminal 845 is at a high level, transistors 841 and 844 are OFF, and transistor 8 is turned off.
42 and 843 are turned on, and the motor 64 rotates in the forward direction. When the input terminal 845 is at a low level, transistors 842 and 843 are turned off, transistors 841 and 844 are turned on, and the motor 64 is rotated in reverse. The control circuit 84 controls the motor 6 according to operating conditions.
Rotate 4 forward or reverse to change the valve timing.

In the ignition timing control according to the present invention, when the valve timing is switched from one side to the other, that is, when the camshaft 32 is rotated by a predetermined angle with respect to the crankshaft 24 by the action of the valve timing control device 41, the ignition timing is The lead angle value calculated in the timing calculation routine is corrected by that amount, and thereby the distributor shaft 4 connected to the camshaft 32
The ignition timing is maintained so that it does not deviate from the calculation even if the zero is turned. Such control of the present invention is performed by software. The configuration of this software will be explained below using a flowchart. In addition, this software uses the control circuit ROM88.
Needless to say, it is written in the form of a program.

First, FIG. 6 shows a flowchart of a routine for controlling valve timing. 100 indicates the start of this routine, which can be a time interrupt routine every 30 msec, for example. In 102,
Signals from the crank angle sensor 39, load sensor 80, and temperature sensor 81 are taken in to determine which valve timing the engine is requesting. Here, for convenience, the valve timing of "1" is the valve timing obtained when the motor 64 is rotated in the normal direction, and the valve timing of "0" is the valve timing obtained when the motor 64 is rotated in the reverse direction.

If it is recognized that the valve timing should be set to "1" (Yes), the process proceeds to 104 and the valve timing display flag f is verified. This flag f becomes 1 when the valve timing is “1” and becomes “0”.
It shall be 0 when . If NO, 10
Set the flag to 1 at 6, then set motor 6 at 108.
Issue 4 forward rotation command. At this time, input/output port 8
3 to the input terminal 845 of the motor drive circuit 84.
A high signal is input, the motor 64 rotates forward, and the valve timing becomes "1". In the next step 110, the ignition timing correction value C is set to 0. 112 indicates a return to the main routine.

If the answer is Yes at 104, the valve timing has already been switched to "1", so nothing is done and the process returns to the main routine at 112.

If it is recognized at 102 that the valve timing should be set to "0", the process branches to NO, and at 114 the flag f is verified. If NO, flag f is lowered in step 116, and then a reverse rotation command for the motor 64 is issued in step 118. At this time, a Low signal enters the input terminal 845 of the motor drive circuit 84 from the input/output port 83,
The motor 64 rotates in the reverse direction and the valve timing becomes "0". In the next step 120, the ignition timing correction value C is set to θo degrees.

If 114 is Yes, the valve timing has already been switched to "0", so don't do anything and go to 112.
Return to the main routine.

FIG. 7 shows a part of the main routine for calculating the ignition timing. At 122, the basic ignition timing θ is calculated based on the engine operating conditions.
At step 124, the ignition timing is determined by adding the correction value C calculated at step 110 or 120 in FIG. 6 to the basic ignition timing θ calculated in this way. This has the following meaning. That is, by switching the valve timing as described above, the camshaft 32 is moved to the crankshaft 2.
4, the crank angle sensor 39, which monitors the position of the distributor shaft 40 connected to the camshaft 32, changes the position of the distributor shaft 40 when the valve timing is "1" as well as when it is "0". Even if the position of the crankshaft 24 is the same, the detection results will differ by the amount of twist of the camshaft. 120 correction θo
is to correct this deviation so that the correct crankshaft position can be seen no matter which valve timing is "1" or "1".

The ignition timing thus calculated is used to drive the igniter 85 at that crank angle by executing an ignition routine, which will not be described in detail.

As described above, in the present invention, by correcting the calculated value of the ignition timing by the amount of twist of the camshaft when changing the valve timing, it is possible to maintain the calculated value of the ignition timing when the valve timing control device is operating. can.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing the internal combustion engine of the present invention, FIG. 2 is a vertical cross-sectional view of the valve timing control device, FIG. 3 is a view taken in the direction of the arrow in FIG. 21... Spark plug, 24... ...Crankshaft, 32...
...Camshaft, 36...Distributor, 41...
...Valve timing control device.

Claims (1)

[Claims] 1. It has means for controlling valve timing by changing the phase between the crankshaft and the camshaft,
In an ignition timing control device for an internal combustion engine in which a distributor is connected to a camshaft, means for controlling ignition timing according to engine operating conditions;
and an ignition timing control device for an internal combustion engine, comprising means for correcting a calculated value of ignition timing in accordance with a phase change between a crankshaft and a camshaft controlled by a valve timing control means.