JPH09217614A - Intake and exhaust valve drive control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure favourable detection precision of a rotational phase difference by a cam angle sensor by avoiding influence of rotational torque variation of a camshaft and to prevent abrasion, etc. SOLUTION: An operating angle of a suction valve 24 by a rotational phase difference between a drive shaft and a camshaft is controlled by changing relative angular velocity in accordance with concentric - eccentric oscillation of a control system 3 provided between the drive shaft 1 and the camshaft 2. An operation system 4 to control the above-mentioned control system has an electromagnetic pick up type cam angle sensor 30 to output an information signal to a controller 31 and is furnished with a projected part 32 for a pick-up of the cam angle sensor 30 between a first flange part 5 and a cam 2a of the camshaft. Additionally, the cam angle sensor 30 and the projected part 32 are set at a position where their pick-up point becomes the maximum point of a change of the above-mentioned rotational phase difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake / exhaust valve drive control device for varying the opening / closing timing of intake / exhaust valves in accordance with the operating state of an internal combustion engine for an automobile.

[0002]

2. Description of the Related Art As a conventional intake / exhaust valve drive control device of this type, Japanese Patent Application No. 7-85101 filed previously by the present applicant.
There are those described in the issue.

The outline will be described with reference to FIG. 9. The drive shaft 1 to which the rotational force is transmitted from the crankshaft of the engine and the outer periphery of the drive shaft 1 are coaxially arranged with a constant gap and each cylinder is arranged. The camshaft 2 is divided into parts and has a cam 2a for operating an intake valve (not shown) on the outer periphery, and the camshaft 2 is provided between the end of each camshaft 2 and the drive shaft 1. Control mechanism 3 for changing the rotation phase, and the control mechanism 3
And an operating mechanism 4 for eccentrically moving the engine according to the engine operating state.

The control mechanism 3 is provided between the first and second flange portions 5 and 6 provided on the end portion of the camshaft 2 and the drive shaft 1 and between the flange portions 5 and 6, respectively. A disc housing 8 that rotatably holds an annular disc 7 around its circumference, and a slide that is interposed between the annular disc 7 and each of the flange portions 5 and 6 to transmit the rotational force of the drive shaft 1 to each cam shaft 2. It has movable first and second pins 9 and 10, and each of these pins 9 and 10 has a tip portion 9a, 1 having a width across flats.
0a is a U formed on the outer peripheral portions of the flange portions 5 and 6
It is slidably provided in the character-shaped first and second engagement grooves 11 and 12.

As shown in FIG. 8, the actuating mechanism 4 is arranged substantially parallel to the camshaft 2 and has a control shaft 14 provided with an eccentric cam 13 for swinging the disc housing 8 at one end thereof. A hydraulic cylinder 15 provided on the other end side of the control shaft 14 for controlling the rotational position of the control shaft 14 via a control plate 14a.
And the first and second pressure receiving chambers 15a in the hydraulic cylinder 15,
An electromagnetic actuator 16 for controlling the hydraulic pressure of 15b via a spool valve (not shown) and a contact type potentiometer 17 for detecting the rotational angle position of the control shaft 14 are provided.

In the hydraulic cylinder 15, the internal piston 18 slides according to the relative pressure in the pressure receiving chambers 15a and 15b to move the piston rod 19 forward and backward, and the control plate 14a is normally or reversely moved via the pin 20. It is designed to rotate. The electromagnetic actuator 16 is operated by a control pulse signal from a controller 21 incorporated in the computer, and the controller 21 is operated by an information signal from various sensors such as a crank angle sensor and an air flow meter. And the rotational phase difference between the drive shaft 1 and the cam shaft 2 is detected based on the information signal fed back from the potentiometer 17.

The potentiometer 17 has a sliding rod 17a on a cam surface 23a of a cam 23 fixed to the other end of the control shaft 14 by a bolt 22, as shown in FIG.
Are brought into contact with each other, and the resistance voltage is changed depending on the sliding position of the sliding rod 17a which advances and retreats according to the rotational position of the cam 23.

When the engine is running at low speed, the duty ratio of the control pulse signal is changed from the controller 20 to the electromagnetic actuator 16 to operate the spool valve (not shown), whereby the piston rod 19 of the hydraulic cylinder 15 is advanced. By the control plate 14
The control shaft 14 rotates clockwise in the figure via a. Therefore, the disc housing 8 is swung by the eccentric cam 13 so that the center of the annular disc 7 becomes X of the drive shaft 1.
Eccentric from.

For this reason, the first and second pins 9 and 10 slide in the radial direction along the first and second engaging grooves 11 and 12 for each rotation of the drive shaft 1, and the second pin 10 is moved. When is close to the axis X of the drive shaft 1, the first pin 9 is separated from the axis X. Therefore, in this case, the annular disc 7 has a large angular velocity with respect to the drive shaft 1, and the camshaft 2 also has a large angular velocity. Therefore, the camshaft 2 is in a state in which the speed is doubled with respect to the drive shaft 1. Therefore, the rotational phase difference between the drive shaft 1 and the cam shaft 2 is as shown in FIG. 10B.
When the angular velocity of the camshaft 2 is relatively large, the rotational phase with respect to the drive shaft 1 is
When the angular velocity of the camshaft 2 becomes relatively small, the rotational phase is delayed until the rotational speeds of the camshaft 2 and the camshaft 2 become uniform.

As shown in FIG. 10B, the same phase point P exists in the middle of the maximum points (Q points) of the respective amplitudes of the rotational phase difference, and the change in the rotational phase in FIG. Is shown in FIG.
As shown by the broken line A, the valve opening timing before point P is delayed,
The valve closing timing after point P advances, and the overall control is made small. Therefore, the valve overlap of the intake valve 24 is reduced, the residual gas in the combustion chamber is reduced, and stable combustion improves fuel efficiency. Further, the intake valve charging efficiency is improved by the early valve closing timing control, and the low speed torque can be increased.

On the other hand, at the time of high engine speed, the annular disk 7
Does not coincide with the axis X of the drive shaft 1, and there is no difference in rotational phase between the drive shaft 1 and the camshaft 2. Therefore, as the drive shaft 1 rotates, the camshaft 2 passes through the control mechanism 3.
Rotates synchronously with the drive shaft 1, and the intake valves 24 by the cams 6 and 6
10A becomes large as shown by the solid line in FIG. 10A, the valve opening timing is advanced and the valve closing timing is delayed, so that the intake charging efficiency using the intake inertial force is improved.

[0012]

By the way, the camshaft 2 usually has positive and negative rotational torque fluctuations due to the spring force of the valve spring when the intake valve 24 is opened and closed, that is, at the beginning and end of the cam lift. It is well known that the alternating torque fluctuation) occurs.

However, in the conventional device, the potentiometer 17 for detecting the rotational angle position of the control shaft 14 has the sliding rod 17a as the cam surface 2 as described above.
The rotational angle position of the control shaft 14 is detected by moving back and forth while making sliding contact with the 3a to change the resistance voltage. Therefore, the positive and negative rotational torque fluctuations generated in the camshaft 2 are transmitted to the shaft 14 and further transmitted to the inside of the potentiometer 17 via the cam 23 and the sliding rod 17a. As a result, vibration is generated between the brush and the resistor built in the potentiometer 17, which not only lowers the detection accuracy of the cam rotation angle, but also wears the brush and the resistor.

[0014]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned conventional problems.
A drive shaft that is rotationally driven by the engine, a cam shaft that is provided relatively rotatably on the same axis as the drive shaft, and has a cam that operates an intake / exhaust valve on the outer circumference, and a cam shaft that is concentric with the drive shaft. A control mechanism that eccentrically moves to change the relative rotational phase of the drive shaft and the camshaft to change the operating angle of the intake and exhaust valves, and the control mechanism that changes the drive shaft of the drive shaft according to the engine operating state. An intake / exhaust valve drive control device having a controller for calculating a rotational phase difference between a drive shaft and a cam shaft, the operating mechanism detecting the rotational angle of the cam shaft. Then, a cam angle sensor that outputs the rotation angle information signal to the controller is provided in a non-contact state with the cam shaft, and the cam angle sensor is picked up at a predetermined position on the outer circumference of the cam shaft. A protrusion for up provided, the pick-up point of the protrusion by the cam angle sensor, the rotational phase difference between the drive shaft and the cam shaft is characterized in that it is set to a position that occurs.

The invention of claim 2 is characterized in that the pick-up point of the projection by the cam angle sensor is set to the maximum point of change in the rotational phase difference between the drive shaft and the cam shaft.

The invention of claim 3 is characterized in that the protrusion is a cam nose portion of the cam.

According to the present invention, instead of using the conventional contact type potentiometer for detecting the rotational phase difference between the drive shaft and the cam shaft, for example, an optical sensor rotation for detecting the rotational angle of the drive shaft is used. Since the angle sensor and, for example, an electromagnetic pickup type cam angle sensor that detects the rotational angle position of the cam shaft are used, the cam angle sensor and the cam shaft are in a non-contact state. Therefore, the cam angle sensor is completely unaffected by fluctuations in the rotational torque of the camshaft.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention, in which a drive shaft 1, a cam shaft 2, a control mechanism 3 for changing a rotational phase difference between the both 1, 2 and an operating mechanism 4, etc. Since the configuration is the same as that of the conventional example, duplicate description will be omitted.

The present invention eliminates the conventional potentiometer, and the drive shaft 1 detects the rotational angle position by a rotational angle sensor such as an optical sensor, while the camshaft 2 rotates by an electromagnetic pickup type cam angle sensor 30. The angular position is detected and each information signal is output to the controller 31.

More specifically, the cam angle sensor 3 will be described.
0 is fixed to, for example, a rocker cover or the like as shown in FIGS. 1 and 2, and is in a non-contact state with the camshaft 2, while the cam 0 between the cam 2a of the camshaft 2 and the first plunger 5 is A protrusion 32 for pickup is provided on the outer peripheral surface so as to protrude in the radial direction. In addition, the cam angle sensor 3
0 and the protrusion 32 have a coincident point, that is, a pickup point, a rotational phase difference between the drive shaft 1 and the cam shaft 2 when the annular disc 7 is eccentric (at a small operating angle) as shown in FIG. Instead of the P point (concentric) position which is not performed, each is relatively arranged at the position of the maximum point (Q point) of the rotational phase difference.

By the way, when the control shaft 14 is rotated so as to control from the large operating angle side to the small operating angle side at the time of shifting from the high engine speed region to the low engine speed region, the drive shaft 1 and the cam shaft 2 rotate. The phase difference continuously increases from a small rotational phase difference in the maximum operating angle state as shown in FIGS. 2 and 3. Then, the controller 31 converts this increase amount into an operating angle amount based on the information signals output from the rotation angle sensor 33 of the drive shaft 1 and the cam angle sensor 30 of the cam shaft 2, respectively.

That is, this controller 31 is shown in FIG.
As shown in FIG.
From the rotational phase difference detecting means 34 for calculating the rotational phase difference between the drive shaft 1 and the camshaft 2 by inputting the current rotational angle positions of the drive shaft 1 and the camshaft 2, a crank angle sensor 35, an air flow meter 36, and the like. Engine speed from various sensors,
A target value determining means 37 for detecting a current engine operating state from an information signal such as a load to determine a target value of the operating angle is provided. Further, it has a control circuit 38 for calculating the operation control value of the electromagnetic actuator 16 by inputting the information signals from the rotational phase difference detection means 34 and the target value determination means 37, respectively. Further, the control circuit 38 is supposed to estimate the operating angle of the intake valve 24 based on the information signal from the rotational phase difference detecting means 34.

The specific control of the controller 31 will be described below with reference to the flowchart of FIG.

First, in section S1, the rotational speed N of the crank shaft from the crank angle sensor, the intake air amount Q from the air flow meter, and the throttle opening θ _T from the throttle opening sensor are read. Next, section S
In step 2, the basic injection amount T _P of the fuel injection valve (not shown) is calculated based on the information signals, and in section S3,
The target value S _T of the valve timing operating angle is read from the map preset by N and T _P. continue,
In section S4, the current camshaft operating angle of the camshaft 2, that is, the operating angle S with respect to the drive shaft 1, is estimated based on the information signal from the rotational phase difference detecting means 34.

Further, in section S5, the difference value ΔS is obtained by subtracting the camshaft operating angle S from the operating angle target value S _T. Subsequently, in section S6, it is determined whether or not the difference value ΔS is less than or equal to a predetermined value α, and if not, it is determined in section S7 whether the difference value ΔS is greater than 0, that is, whether the difference value ΔS is positive or negative. Determine. Here, when the difference value ΔS is negative, that is, when the camshaft operating angle S exceeds the target value S _T , it is in the low rotation and low load region, for example, so that the duty ratio is set to 0% in the section S8. Then, the electromagnetic force of the electromagnetic actuator 16 is controlled to zero.

Therefore, the spool valve (not shown) provided at the tip of the drive rod of the electromagnetic actuator 16 is urged to one side by the spring force of the coil spring to switch the flow path, and the inside of the second pressure receiving chamber 15b in the cylinder 15 is switched. Is drained and hydraulic pressure is supplied to the first pressure receiving chamber 15a. As a result, the piston 18 advances and the piston rod 19 causes the control plate 14 to move through the pin 20.
By tilting a in the clockwise direction in FIG. 4, the control shaft 14 rotates maximally in the clockwise direction in the figure, causing the eccentric cam 13 to rotate in the same direction.

Therefore, the disc housing 8 swings upward, and the center of the annular disc 7 is the center X of the drive shaft 1.
Eccentric to the maximum. Therefore, the first and second pins 9 and 10
And the like, the angular velocity of the annular disk 7 is changed to rotate at an unequal angular velocity. As a result, the camshaft 2 is partially accelerated with respect to the drive shaft 1, and the intake valve 24
Is controlled to a small operating angle. Therefore, in the low-speed low-load region, the valve overlap between the intake valve 24 and the exhaust valve is reduced, so that the fuel consumption is improved and the intake charging efficiency is improved due to the early closing timing, so that the output torque can be increased.

If it is determined in section S7 that the difference value ΔS is positive, that is, if the camshaft operating angle S has not reached the target value S _T , it means that the engine is in the high rotation and high load region, and therefore section S9. Then, the processing for increasing the duty ratio to the electromagnetic actuator 16 is performed to increase the electromagnetic force, and the drive rod is advanced to the maximum. For this reason,
The spool valve moves to the maximum other side against the spring force of the coil spring to switch the flow path.

Therefore, this time, while the hydraulic oil in the first pressure receiving chamber 15a is drained to a low pressure, the second pressure receiving chamber 15a
The hydraulic oil is supplied to the inside of b to become a high pressure. by this,
The piston 18 moves in the maximum backward direction (to the right),
The piston rod 19 tilts the control plate 14a through the pin 20 in the maximum counterclockwise direction. For this reason, the control shaft 14 rotates maximally in the counterclockwise direction in the figure, and rotates the eccentric cam 22 in the same direction.

Therefore, the disc housing 8 swings downward, and the center Y of the annular disc 7 decenters from the center X of the drive shaft 1 in the opposite direction to the above. For this reason, the angular velocity of the camshaft 2 becomes smaller than the above with respect to the annular disc 7, the camshaft 2 is partially decelerated with respect to the drive shaft 1, and the intake valve has a large operating angle. Controlled. Therefore, the valve overlap becomes large,
The intake charge efficiency is improved and high output torque and the like can be obtained.

If it is determined in the section S6 that the difference value ΔS is less than or equal to the predetermined value, it means that the camshaft operating angle S substantially matches the current engine operating state. Move to. Here, a process of fixing the duty ratio to 50% is performed. Therefore, the spool valve is held at the substantially intermediate movement position to close each flow passage. Therefore, each pressure receiving chamber 15a, 15b
The supply and discharge of hydraulic oil to the piston 18 are blocked, and the piston 18 is held at a predetermined arbitrary moving position. As a result, it becomes possible to control the intake valve 24 to a substantially intermediate operating angle via the control shaft 14 and the control mechanism 3.

As described above, in this embodiment, the rotation phase difference between the drive shaft 1 and the cam shaft 2 is not detected by the contact type potentiometer as in the conventional case, but the rotation angle sensor 33 on the drive shaft 1 side is used. And the cam angle sensor 30 on the side of the camshaft 2 are used, and the electromagnetic angle sensor of the cam angle sensor 30 that is not in contact with the camshaft 2 is used. Never. Therefore, it is possible to always obtain good position detection accuracy of the cam angle sensor 30 and prevent wear and the like from occurring.

Moreover, the matching point (pickup point) between the cam angle sensor 30 and the protrusion 32 is the maximum point (Q) of the rotational phase difference.
Since the cam angle sensor 30 is located at a point), the rotational phase difference between the cam angle sensor 30 and the cam angle sensor 30 can be reliably and accurately detected even if the resolution is set low.

FIG. 7 shows a second embodiment of the present invention, in which the pick-up protrusion of the cam angle sensor 30 is not provided on the camshaft 2 as in the first embodiment, but the cam nose portion 2b of the cam 2a is provided. It was used. Then, the position of the cam angle sensor 30 is set to a position where it becomes the maximum point (Q point) of the rotational phase difference in relation to the cam nose portion 2b.

Therefore, according to this embodiment, the same operational effect as that of the first embodiment can be obtained, and since the cam nose portion 2b is used as the protrusion for pickup,
The manufacturing workability of the camshaft 2 is improved, and it is also advantageous in terms of cost.

The present invention is not limited to the configuration of the above-described embodiment, and can be applied to, for example, the one in which the operating mechanism 4 does not use a hydraulic cylinder, a control shaft or the like, and can also be applied to the exhaust side. Is.

[0037]

As is apparent from the above description, according to the present invention, the means for detecting the rotational phase difference between the drive shaft and the cam shaft does not use the contact type potentiometer as in the prior art, but the cam. Since, for example, an electromagnetic pickup-type cam angle sensor that is in non-contact with the shaft is used, the cam angle sensor is not affected by the rotational torque fluctuation generated in the cam shaft. As a result, good detection accuracy of the cam angle sensor is always obtained, and the control accuracy of the valve operating angle is improved.

Further, since the cam angle sensor is not subjected to the rotational torque fluctuation at all, it is possible to prevent the deterioration of the durability due to the occurrence of wear or the like.

Moreover, since the cam angle sensor and the projection are set at the position where the pickup point is the maximum point of the rotational phase difference, even if the resolution of the cam angle sensor is set low,
It is possible to detect the rotational phase difference reliably and with high accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part showing a first embodiment of the present invention.

FIG. 2 is a schematic view showing a rotational phase difference between a drive shaft and a cam shaft and a valve lift characteristic of the present embodiment.

FIG. 3 is a diagram showing a changing state of a rotational phase difference between a drive shaft and a cam shaft according to the present embodiment.

FIG. 4 is a perspective view showing an operating mechanism used in this embodiment.

FIG. 5 is a control block diagram of the present embodiment.

FIG. 6 is a flowchart showing the operation of this embodiment.

FIG. 7 is an explanatory diagram showing a second embodiment of the present invention.

FIG. 8 is a perspective view showing a conventional operating mechanism.

FIG. 9 is a cross-sectional view of essential parts showing a conventional intake / exhaust valve drive control device.

FIG. 10 is a diagram showing a rotational phase difference between a drive shaft and a cam shaft and a valve lift characteristic in a conventional example.

[Explanation of symbols]

 1 ... Drive shaft 2 ... Cam shaft 2a ... Cam 2b ... Cam nose part 3 ... Control mechanism 4 ... Actuating mechanism 30 ... Cam angle sensor 31 ... Controller 32 ... Protrusion part Q point ... Maximum point

Claims (3)

[Claims] 1. A drive shaft rotationally driven by an engine,
A cam shaft which is provided coaxially with the drive shaft and is rotatable relative to the drive shaft, and a cam shaft which has a cam for actuating an intake and exhaust valve on the outer circumference; A control mechanism for varying the operating angle of the intake and exhaust valves by changing the relative rotational phase of
An intake / exhaust valve having an operating mechanism for swinging the control mechanism with respect to the axis of the drive shaft in accordance with the engine operating state, the operating mechanism having a controller for calculating a rotational phase difference between the drive shaft and the camshaft. In the drive control device, a cam angle sensor that detects the rotation angle of the cam shaft and outputs the rotation angle information signal to the controller is provided in a non-contact state with the cam shaft, and at a predetermined position on the outer circumference of the cam shaft. A protrusion for picking up the cam angle sensor is provided, and a pickup point of the protrusion by the cam angle sensor is set at a position where a rotational phase difference between the drive shaft and the cam shaft is generated. Exhaust valve drive control device. 2. The intake / exhaust valve drive control for an internal combustion engine according to claim 1, wherein a pickup point of the protrusion by the cam angle sensor is set to a maximum point of a rotational phase difference between the drive shaft and the cam shaft. apparatus. 3. The intake / exhaust valve drive control device for an internal combustion engine according to claim 1, wherein the protrusion is a cam nose portion of the cam.