JPH06264705A - Valve timing control device for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [Purpose] The responsiveness of the valve timing control device on the advance side can be improved, and the cam journal can be made compact. [Structure] Advance angle side control passage 16 in camshaft 2
Has one end communicated with the second pressure chamber 15, and the other end communicated with an opening 16a provided at the center of the cam journal 2a in the width direction. The opening portion 16 a is a passage 16 for advancing angle on the cylinder head side that opens in the bearing portion of the cylinder head 1.
Is in communication with. One end of the retard side control passage 17 in the camshaft 2 is communicated with the first pressure chamber 14 through the through hole 5a of the bolt 5, and the other end is an opening 17a provided on the thrust surface side of the cam journal portion 2a. Is in communication with.
The opening 17a communicates with the advance angle control passage 17 on the cylinder head 1 side that opens on the thrust surface side of the cam journal 2a in the bearing portion of the cylinder head 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device for controlling the opening / closing timing of intake / exhaust valves according to the operating state of an internal combustion engine.

[0002]

2. Description of the Related Art Heretofore, a valve timing control device has been proposed in which the rotational phase of a camshaft is changed in accordance with the operating state of an internal combustion engine to advance or delay the valve opening / closing timing. As one of them, there is a valve timing control device in which a hydraulic chamber is provided on one end side in the axial direction of a cylindrical ring gear having a helical spline, and a spring is arranged on the other end side chamber. This device moves the ring gear depending on the magnitude relationship between the hydraulic pressure of the hydraulic oil pumped to the hydraulic chamber and the spring force of the spring. Then, for example, when retarding the closing timing of the intake valve, the pressure feed of the hydraulic oil to the hydraulic chamber is stopped, and the ring gear is moved only by the biasing force of the spring. On the contrary, when advancing the closing timing of the intake valve, the hydraulic oil is pumped to the hydraulic chamber to move the ring gear against the biasing force of the spring.

Therefore, when retarding the ring gear, it depends on the biasing force of the spring, and it is necessary to increase the biasing force in order to obtain a good response. However,
When the urging force is increased, when the engine speed falls below the specified speed and the hydraulic pressure of the hydraulic oil is low, sufficient hydraulic pressure to compress the spring cannot be obtained and responsiveness during advancing is reduced. There is a problem that gets worse.

In order to solve the above problems, a first hydraulic chamber and a second hydraulic chamber are provided at both ends in the axial direction of the ring gear as shown in Japanese Patent Laid-Open No. 63-131808. It has been proposed that the ring gear can be moved in the axial direction of the cam shaft by sending hydraulic oil to each hydraulic chamber. In this technique, two passages for supplying hydraulic oil to both hydraulic chambers are opened in a cam journal of a camshaft, and two passages opened in the cam journal are a pair of hydraulic passages provided in a bearing portion of a cylinder block. It is possible to communicate with each.

[0005]

However, when a pair of passages are provided in a bearing portion having a narrow width, there is a problem that the diameter of the passages is reduced or the sealing performance for the other passage is insufficient, resulting in poor responsiveness. It was In order to solve this problem, it is sufficient to widen the bearing portion of the passage on the advance side in particular, but this will increase the size of the engine structure.

In general, when the engine speed is low (the hydraulic pressure is low), which has a problem of responsiveness, the advance side has a high torque, and the responsiveness of the advance side when the throttle is opened gives the drivability. The impact will be strong. In general, the response on the advance side is worse than the response on the retard side for the following reason. That is, when advancing, the thrust force due to the cam torque acts against the hydraulic pressure that works to move the ring gear to the advancing side. further,
When a spring for exerting a spring force on the retard side is provided for the ring gear, hydraulic pressure acts against the thrust force due to the cam torque and the spring force of the spring. On the other hand, in the case of retarding, the thrust force due to the hydraulic pressure and the cam torque acting to move the ring gear to the retard side is exerted on the ring gear. Further, when a spring for exerting a spring force on the retard side is provided for the ring gear, the thrust force due to the cam torque and the spring force of the spring are added to the hydraulic pressure. Therefore, the responsiveness on the advance side is generally worse than that on the retard side.

An object of the present invention is to provide a valve timing control device capable of improving the response on the advance side and making the journal compact.

[0008]

In order to solve the above problems, the present invention provides a pulley provided on the outer periphery of a camshaft for driving a valve of an internal combustion engine, and a pulley interposed between the camshaft and the pulley. A cylindrical ring gear having a spline on the inner and outer peripheral surfaces, and at least one of which is a helical spline, and a fluid from a pressurized fluid supply source is introduced into pressure chambers provided at both ends of the ring gear, and the fluid is supplied to the ring gear. Equipped with an advance control passage and a retard control passage for acting on both ends, the ring gear is moved in the axial direction of the camshaft by the urging force of the fluid pressure from the pressurized fluid supply source to drive the pulley. The force is transmitted to the camshaft by a helical spline, and the rotational phase of the pulley and camshaft is changed to adjust the valve opening / closing timing. In the timing control device, both passages are opened in the cam journal for the thrust bearing of the camshaft, and the opening of the retard control passage is provided toward the thrust surface in the cam journal. is there.

[0009]

With the above structure, since the retard control passage is opened toward the thrust surface in the cam journal, the advance control passage can be provided near the center of the narrow cam journal. Unlike the conventional case, the passage cross-sectional area can be formed wider, and the response on the advance side is improved. Since the opening of the advance angle control passage can be provided near the center of the cam journal, the distance between the opening of the advance angle control passage and the opening of the retard angle control passage can be made longer than before. , The sealing property between both openings is secured. At the same time, the sealability between the opening of the advance control passage and the atmosphere side is secured.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the valve timing device for an internal combustion engine according to the present invention will be described below with reference to FIG.

As shown in FIG. 1, a cylinder head 1 of an engine as an internal combustion engine is provided with a cam shaft 2 for an intake valve that extends in the front-rear direction (left and right in FIG. 1). A journal portion 2a is formed on the outer circumference of the camshaft 2, and the journal portion 2a is rotatably supported by the cylinder head 1 and the bearing cap 3. A cylindrical fixed gear 4 is fastened and fixed by a bolt 5 to the front end of the camshaft 2. A timing pulley 6 is rotatably provided on the outer circumference of the front end of the camshaft 2. The front end of the boss portion 7 of the timing pulley 6 is loosely inserted between the fixed gear 4 and the outer periphery of the cam shaft 2, and the rear end of the boss portion 7 slidably contacts a flange 2b protruding from the outer periphery of the cam shaft 2. It is touched.

A timing belt 8 is wound around the timing pulley 6, and a crankshaft (not shown) is rotated by the timing belt 6 via the timing belt 8.
Be transmitted to. A cap 9 is fastened and fixed to the front end surface of the timing pulley 6 with a bolt 10. The cap 9 covers the front end of the camshaft 2. Between the timing pulleys 6 is arranged a cylindrical gear 11 which is fastened and fixed by the bolts 10. A space surrounded by the timing pulley 6, the gear 11, and the cap 9 is an annular space 12, and a ring gear 13 having a substantially double cylindrical shape is arranged in the annular space 12. The timing pulley 6 and the fixed gear 4 are drivingly connected by the ring gear 13. That is, the helical spline 13 is provided on the outermost circumference and the innermost circumference of the ring gear 13, respectively.
a and 13b are formed. On the other hand, the helical spline 4 is provided on the outer periphery of the rear end of the fixed gear 4 and the inner periphery of the gear 11.
a and 11a are formed. The helical splines 13a and 11a mesh with each other, and the helical splines 13b and 4a mesh with each other.

Therefore, when the rotation of the crankshaft is transmitted to the timing pulley via the timing belt 8, the timing pulley 6 and the fixed gear 4 connected by the ring gear 13 are integrally rotated, and the camshaft 2 is rotated. Driven.

A ring gear 13 in the annular space 12
The front side of is a first pressure chamber 14, and the rear side of the ring gear 13 is a second pressure chamber 15. This pressure chamber 14,
A working oil as a fluid is supplied to 15. That is,
An advance angle control passage 16 is formed in the front end portion of the camshaft 2, the boss portion 6a of the timing pulley 6 and the cylinder head 1. One end of the advance side control passage 16 in the camshaft 2 is communicated with the second pressure chamber 15 through the opening of the boss portion 6a, and the other end is an opening provided in the center portion of the cam journal portion 2a in the width direction. 16a. The opening 16a communicates with the advance control passage 16 on the cylinder head side, which opens in the bearing of the cylinder head 1.

A retard angle control passage 17 is formed in the front end axis of the camshaft 2, the bolt 5 and the cylinder head 1. That is, one end of the retard side control passage 17 in the camshaft 2 is communicated with the first pressure chamber 14 through the through hole 5a formed along the axis of the bolt 5, and the other end is in the cam journal portion. It communicates with an opening 17a provided on the thrust surface side of 2a. And the opening 17a
Is the cam journal 2 in the bearing portion of the cylinder head 1.
It is communicated with the advance angle control passage 17 on the cylinder head 1 side that opens to the thrust surface side of a.

The advance angle control passage 16 and the retard angle control passage 1
7 is connected to an oil pan 20 via an electromagnetic switching valve 18 and an oil pump 18 as a pressurized fluid supply source. The oil pump 19 is drivingly connected to the crankshaft of the engine, and works in conjunction with the operation of the engine.
The hydraulic oil in 0 is pumped up and supplied to either hydraulic chamber via the advance angle control passage 16 or the retard angle control passage 17 selected by the electromagnetic switching valve 18. By this supply, the hydraulic pressure as the fluid pressure acts on the ring gear 13.

Further, the electromagnetic switching valve 18 is a 4-port 3-position type electromagnetic control valve, which is a neutral position, a retard angle control position and an advance angle control position due to the excitation / demagnetization of the solenoid 18a of the electromagnetic switching valve. It is designed to be switched to the position. That is, when the electromagnetic switching valve 18 is located at the neutral position, the supply of hydraulic oil to both the advance and retard control passages 16 and 17 is stopped. When the electromagnetic switching valve 18 is located in the retard control position, the retard control passage 17 serves as a hydraulic oil supply passage to the first pressure chamber 14, and the advance control passage 16 extends from the second pressure chamber 15. It is a return path for returning the hydraulic oil to the oil pan 20. Further, when the electromagnetic switching valve 18 is located at the advance control position, the advance control passage 16 is provided.
Serves as a supply passage of hydraulic oil to the second pressure chamber 15, and the retard control passage 17 serves as a return passage for returning the hydraulic oil from the first pressure chamber 14 to the oil pan 20.

An electronic control unit (ECU) 22 is provided to control the operation of the electromagnetic switching valve 18. EC
U22 includes a central processing control unit (CPU), various memories for preliminarily storing a predetermined control program and the like, and a primary storage for the calculation result of the CPU, and the like, and each of these parts, each part, an input circuit, an external output circuit, etc. Are connected by a bus as a logical operation circuit. An air flow meter 23 that is sucked into the engine through an intake passage is connected to an external input circuit of the ECU 22. Similarly, a crank angle sensor 24 arranged near the crankshaft and a cam angle sensor 25 arranged near the camshaft 2 are connected to the external input circuit. Then, the ECU 22 reads the output signals from the sensors 23, 24, 25 as input values via the external input circuit. Then, the ECU 22 suitably controls the solenoid 18a of the electromagnetic switching valve 18 connected to the external output circuit based on these input values.

Then, when the electromagnetic switching valve 18 is actuated to the retard control position based on the control signal from the ECU 22,
Supply of hydraulic oil to the retard control passage 17 is allowed, and the hydraulic oil is introduced from the retard control passage 17 into the first pressure chamber 14. Then, the hydraulic pressure presses the ring gear 13 in one axial direction (to the right in FIG. 1). As a result, the camshaft 2 is twisted and the rotational phase with the gear 11 is deviated. That is, the opening / closing of the intake valve is delayed, and the valve overlap between the intake valve and the exhaust valve in the intake stroke is reduced.

On the contrary, when the electromagnetic switching valve 18 is operated to the advance control position based on the control signal from the ECU 22,
Supply of hydraulic oil to the advance angle control passage 16 is allowed, and the hydraulic oil is introduced from the advance angle control passage 16 into the second pressure chamber 15. Then, the hydraulic pressure presses the ring gear 13 in one axial direction (leftward in FIG. 1). As a result, the camshaft 2 is twisted in the opposite direction to the above and the rotational phase with the gear 11 is deviated. That is, the opening and closing of the intake valve is accelerated, and the valve overlap between the intake valve and the exhaust valve in the intake stroke is increased.

Next, the operation of the structure of the valve timing control device constructed as described above will be described. In this embodiment, the retard control passage 17 of the camshaft 2 in the journal portion 2a is opened toward the thrust surface of the cam journal portion 2a. Therefore, the advance control passage 1
The opening 6 can be provided near the center of the narrow journal portion 2a. Therefore, the cross-sectional area of the advance angle control passage 16 can be formed wider than in the conventional case, and the responsiveness on the advance angle side can be improved.

Further, the opening 16 of the advance angle control passage 16 is provided.
Since a can be provided in the vicinity of the center of the journal portion 2a, the distance between the opening 16a of the advance control passage 16 and the opening 17a of the retard control passage 17 can be made longer than before. It is possible to secure the sealing property between the openings 16a and 17a. In addition, the opening 16a of the advance angle control passage 16
It is also possible to secure the sealing property between the air and the atmosphere side.

Further, in this embodiment, the hydraulic pressure is also applied to the thrust surface of the journal portion 2a during the retard control, so that the thrust surface opposite to the thrust surface to which the hydraulic pressure is directly applied is pressed against the bearing portion, and the cam driving torque is increased. Is increased, and the response on the retard side is improved.

The present invention is not limited to the above-mentioned embodiments, but can be arbitrarily modified within the scope of the present invention. (1) In the above embodiment, either one of the helical splines 13a and 13b on the inner and outer circumferences of the ring gear may be changed to a straight spline parallel to the axis. (2) In the above embodiment, the gasoline engine 1 is embodied, but it may be embodied as a diesel engine. (3) In addition to the structure of the above embodiment, a coil spring is provided in the first pressure chamber 14 so as to bias the ring gear 13 toward the retard side. (4) In the above embodiments, the camshaft is used for the intake valve, but it may be embodied as the camshaft for the exhaust valve.

[0025]

As described above in detail, according to the present invention, the responsiveness on the advance side can be improved and the journal can be made compact.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a valve timing control device in an embodiment embodying the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cylinder head, 2 ... Cam shaft, 2a ... Journal part, 4 ... Fixed gear, 6 ... Timing pulley, 8 ... Timing belt, 11 ... Gear, 12 ... Annular space, 13 ...
Ring gears, 13a, 13b ... Helical spline, 1
4 ... 1st pressure chamber, 15 ... 2nd pressure chamber, 16 ... Advance angle control passage, 17 ... Delay angle control passage, 18 ... Electromagnetic switching valve,
19 ... Oil pump.

Claims (1)

[Claims] 1. A pulley provided on the outer periphery of a valve-driving cam shaft of an internal combustion engine, and a pulley interposed between the cam shaft and the pulley,
A cylindrical ring gear having splines on the inner and outer peripheral surfaces, and at least one of which is a helical spline, and a fluid from a pressurized fluid supply source is guided to pressure chambers provided at both ends of the ring gear, and the fluid is supplied to the ring gear. Equipped with an advance control passage and a retard control passage for acting on both ends, the ring gear is moved in the axial direction of the camshaft by the urging force of the fluid pressure from the pressurized fluid supply source to drive the pulley. In a variable valve timing control device in which force is transmitted to a camshaft by a helical spline and the rotational phase of the pulley and the camshaft is changed to adjust the opening / closing timing of the valve, the both passages are thrust bearings of the camshaft. Is opened in the cam journal, and the opening of the retard control passage is provided toward the thrust surface in the cam journal. The valve timing control apparatus for an internal combustion engine characterized in that it.