JPH11141312A - Valve timing control device for internal combustion engine - Google Patents

Abstract

(57) Abstract: To improve the control response of valve timing by increasing the moving speed of a phase converter. SOLUTION: A cylindrical gear 39 meshed between a timing sprocket 21 and a cam shaft 22 is provided with a hydraulic circuit 47.
By moving the pressure receiving chambers 44 and 45 in the axial direction by the hydraulic pressure supplied and discharged relatively to the pressure receiving chambers 44 and 45,
The valve timing is variably controlled by converting the relative rotation phase of No. 2. The outer diameter of the rear end portion 23a of the cylindrical main body 23 is formed larger than the front end portion 23b, and the piston 42 of the rear gear forming portion 39b that receives the oil pressure in both the pressure receiving chambers has a larger diameter at the rear end portion 23a. It was formed as large as the inside diameter to increase the pressure receiving area. In addition, snap ring 26
Thereby, the free movement of the cylindrical main body 23 to the left is restricted.

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 variably controlling the opening and closing timing of intake and exhaust valves according to the operating state of an internal combustion engine.

[0002]

2. Description of the Related Art Various types of conventional valve timing control devices of this type have been provided, and one example thereof is disclosed in Japanese Patent Application Laid-Open No. Hei 2-227507 filed by the present applicant.

[0003] Referring to FIG. 2, a schematic description will be given. A cylindrical timing sprocket 1 driven to rotate by a crankshaft of an engine via a timing belt, and a camshaft 2 having a cam on its outer periphery for opening and closing intake and exhaust valves. A sleeve 3 fixed to one end of the camshaft 2 by a fixing bolt 6 and inserted through the cylindrical main body 1a of the timing sprocket 1, and helical internal and external teeth 4a, 4
a cylindrical gear 4 movable in the camshaft axial direction while meshing with inner teeth 1b formed on the inner periphery of the cylindrical main body 1a and outer teeth 3a formed on the outer periphery of the sleeve 3; A drive mechanism 5 for moving the gear 4 in the axial direction according to the operating state of the engine.

The timing sprocket 1 has a front cover 7 fixed to the sleeve 3 on the front end side.

The cylindrical gear 4 is divided into two parts in the front and rear directions, and a hydraulic circuit 9 of the drive mechanism 5 is provided in a pressure chamber 8 formed between a front end of a front gear component and a front cover 7.
It is configured to move while rotating in the front-rear direction by the hydraulic pressure supplied from the controller and the spring force of the compression coil spring 10.

That is, for example, when the engine is under a low load, the electromagnetic switching valve 11 provided in the hydraulic circuit 9 is turned off, and the hydraulic pressure in the pressure chamber 8 is discharged to the outside via the hydraulic circuit 9, and the pressure in the pressure chamber 8 is reduced. Let low pressure. Thereby, the cylindrical gear 4
Is moved to the maximum forward position by the spring force of the compression coil spring 10 to convert the relative rotational phase between the timing sprocket 1 and the camshaft 2 to one side, and to retard the closing timing of the intake valve (not shown). I do.

On the other hand, when the engine is under a high load, the electromagnetic switching valve 11
Signal is supplied to the pressure chamber 8 through the hydraulic circuit 9 to increase the internal pressure of the pressure chamber 8. As a result, the cylindrical gear 4 moves to the maximum rear position against the spring force of the compression coil spring 10 to convert the relative rotational phase of the timing sprocket 1 and the camshaft 2 to the other side, and to change the phase of the intake valve. The advance timing of the closing timing is controlled.

[0008]

However, in the conventional valve timing control apparatus, the cylindrical body 1a of the timing sprocket 1 has a relatively large thickness in order to secure rigidity due to the formation of the inner teeth 1b. It is formed to be relatively thick and has a relatively small and uniform outer diameter as a whole in relation to the outer diameter of the cylindrical gear 4. Therefore,
The outer diameter of the flange-shaped pressure receiving portion 4c provided at the rear end of the cylindrical gear 4 that receives the hydraulic pressure in the pressure chamber 8 is also set to be small. For this reason, the pressure receiving area of the pressure receiving portion 4c is naturally restricted, and the moving speed of the cylindrical gear 4 due to the hydraulic pressure supplied from the hydraulic circuit 9 is reduced. As a result, the valve timing control according to the change in the engine operating state is performed. Responsibility may not be sufficiently ensured.

[0009]

SUMMARY OF THE INVENTION The present invention has been devised in view of the actual situation of the conventional valve timing control device, and the invention according to claim 1 has a rotating body driven by an engine and a rotating body. A camshaft having a cam for operating an intake / exhaust valve by a rotating force transmitted from a rotating body, a sleeve fixed to one end of the camshaft, and inserted through a cylindrical main body of the rotating body; Phase conversion means interposed between the sleeve and the cylindrical main body, for converting the relative rotation phase between the rotating body and the camshaft by moving in the camshaft axial direction, and integrated with the rear end of the phase conversion means Valve timing provided with a pressure receiving piston provided in the above and a drive mechanism for supplying and discharging hydraulic pressure to a pressure receiving chamber defined at least on the front end side of the piston to move the phase conversion means in the camshaft axial direction. In the control device, a rear end portion of the cylindrical main body is formed to have a larger diameter than a front end portion, and a support portion provided at a rear end portion of the sleeve and rotatably supporting a rear end side of the cylindrical main body. It is characterized in that the outer diameter is formed to be large in accordance with the inner diameter of the rear end portion of the cylindrical body, and the outer diameter of the piston is formed to be substantially the same as the outer diameter of the support portion.

The invention according to claim 2 is characterized in that a regulating member for regulating the free movement of the cylindrical body in the thrust direction is provided on the inner periphery of the rear end of the cylindrical body via a support portion of the sleeve. And

According to a third aspect of the present invention, the regulating member comprises:
It is characterized in that it is constituted by a snap ring that is detachable from the cylindrical main body.

According to a fourth aspect of the present invention, a pressure receiving chamber is formed before and after the piston.

According to the present invention having the above-described structure, the outer diameter of the piston can be increased with an increase in the diameter of the rear end of the cylindrical main body, so that the pressure receiving area is increased. The movement responsiveness can be improved.

[0014]

FIG. 1 shows an embodiment of a valve timing control apparatus according to the present invention. In FIG. 1, reference numeral 21 denotes a timing sprocket which is a rotating body driven to rotate by a crankshaft of an engine via a timing chain, and 22 denotes a timing sprocket. A camshaft having a cam on an outer periphery thereof for opening and closing an intake valve by a rotational force transmitted from a timing sprocket 21, wherein the timing sprocket 21 has a step-shaped cylindrical body 23 and a front end of the cylindrical body 23. And a substantially annular front cover 24 provided in the portion, and the cylindrical main body 23 has a different front and rear outer diameter from a substantially central position,
The outer diameter of the rear end 23a is set sufficiently larger than the outer diameter of the front end 23b, and the rear end 23a is formed to be thinner than the front end 23b.

A gear 21a around which a timing chain (not shown) is wound is provided integrally on the rear outer periphery of the rear end 23a, while a helical gear is formed on the entire inner peripheral surface of the front end 23b. Inner teeth 23c are formed. Cylindrical body 2
A snap ring 26 is detachably fitted and fixed in an annular groove formed substantially at the center of the inner peripheral surface of the rear end 23a of the rear end 23a. Thus, the free movement of the cylindrical main body 23 in the left direction in the figure is restricted.

The camshaft 22 is rotatably supported by a cam bearing groove at the upper end of a cylinder head 27 and a cam bracket 28, and a sleeve 29 housed in the cylindrical main body 23 at one end is fixed by a fixing bolt 30. It is fixed from the axial direction. The sleeve 29 is composed of a large-diameter portion 29a that is a rear-end-side support portion that rotatably supports the inner periphery of a rear end portion 23a of the tubular main body 23, and a small-diameter portion 29b that is fixed by caulking the front cover 24. , Large diameter part 29
a is positioned in the circumferential direction on the camshaft 22 by the positioning pins 31, and the outer teeth 29c are formed at the front end of the outer peripheral surface of the small diameter portion 29b.

The large-diameter portion 29a has an outer diameter slightly smaller than the inner diameter of the inner peripheral surface of the rear end portion 23a of the cylindrical main body 23, and is formed in an annular seal groove formed on the outer peripheral surface. A seal ring 33 that is in pressure contact with the inner peripheral surface is fitted and held.

A female screw hole 22 formed in the inner axial direction of the camshaft 22 is formed in the inner axial direction of the sleeve 29.
The bolt insertion hole 32 which is continuous with the hole a is formed at the outer end of the bolt insertion hole 32 on the front cover 24 side. It is drilled to a depth substantially at the center of the shaft 29b in the axial direction.

On the other hand, the fixing bolt 30 has a head 30a.
Is formed in a cylindrical shape having a diameter slightly smaller than the inner diameter of the insertion hole 34, the outer peripheral surface of which is in close contact with the inner peripheral surface 34 a of the insertion hole 34, and a shaft portion inserted into the bolt insertion hole 32. Male screw 35a screwed into female screw hole 22a at the tip of 35
Are formed. Further, between the head 30a and the shaft 35, a cylindrical portion 3 having an outer shape slightly smaller than the outer diameter of the head 30a.
6 are formed integrally, and the inner end face 3 of the cylindrical portion 36 is formed.
6a and the bottom surface 34b of the fitting hole 34 are in close contact with each other. Also,
A passage hole 51 that forms a part of a first oil passage 49 of the hydraulic circuit 47 described below is formed in the fixing bolt 30. That is, the passage hole 51 is formed continuously in the inner axial direction of the shaft portion 35 excluding the head portion 30a and in the inner radial direction of the cylindrical portion 36. Further, a seal ring 38 is fitted and fixed in an annular seal groove 37 formed on the outer peripheral surface of the head 30 a of the fixing bolt 30, and the outer peripheral surface of the seal ring 38 is formed on the inner peripheral surface of the fitting insertion hole 34. The sealing function is exerted by press-fitting to 34a.

A cylindrical gear 39 which is movable in the axial direction of the camshaft 22 is interposed between the cylindrical main body 23 and the sleeve 29. The cylindrical gear 39 includes front and rear gear components 39a, 39 divided into two parts from a direction perpendicular to the axis.
The gears 39a and 39b are connected by a connecting pin 40 and a coil spring 41 while being urged in a direction approaching each other, and the inner teeth 23c and the outer teeth 23c are formed on the inner and outer peripheral surfaces. Helical internal and external teeth 39c and 39d spirally meshed with the internal teeth 29c are formed.

Further, a piston 42 is integrally provided at the rear end of the rear gear forming portion 39b. The piston 42 is provided between the step 23 d of the cylindrical main body 23 and the sleeve 2.
9 is slidable in the front-rear direction between the large-diameter portion 29a of the sleeve 29 and the outer diameter of the large-diameter portion 29 of the sleeve 29.
It is set to be substantially the same as the outer diameter of “a”. Further, the cylindrical gear 39 is moved forward in the maximum forward direction (leftward in the figure) at a position where the front gear-forming portion 39a abuts against the inner end surface of the front cover 24.
, While the piston 42 abuts on the snap ring 25, the maximum rearward (rightward in the figure) movement position is regulated. A coil spring 43 having a small spring force for urging the cylindrical gear 39 to the maximum forward position while the engine is stopped is elastically mounted between the rear gear forming portion 39b and the large diameter portion 29a of the sleeve 29. ing.

The piston 42 is connected to the cylindrical main body 23.
The first pressure receiving chamber 44 is defined in cooperation with the step 23d of the sleeve 29, and the second pressure receiving chamber 44 is formed between the rear surface and the large diameter portion 29a of the sleeve 29.
A pressure receiving chamber 45 is defined. Further, in the annular groove formed on the outer peripheral surface of the piston 42, both pressure receiving chambers 44 and 45 are provided.
A seal ring 46 for sealing the space is fitted and fixed.

Further, the cylindrical gear 39 is moved in the axial direction (front-back direction) by a drive mechanism. The drive mechanism has a hydraulic circuit 47 for relatively supplying and discharging hydraulic pressure to the first pressure receiving chamber 44 and the second pressure receiving chamber 45, and an electromagnetic switching valve 48 provided in the middle of the hydraulic circuit 47. ing.

The hydraulic circuit 47 has a first oil passage 49 for supplying and discharging hydraulic pressure to and from the first pressure receiving chamber 44 and a second oil passage 50 for supplying and discharging hydraulic pressure to and from the second pressure receiving chamber 45. The first oil passage 49 is provided between the cylinder head 27 and the camshaft 22.
Extending from the radial direction to the axial direction, and further including the passage hole 51 and an annular groove 52 formed on the outer peripheral surface of the cylindrical portion 36.
And Further, the bolt cylindrical portion 3 of the sleeve 29
In the peripheral wall near 6, four first through holes 53 communicating with the annular groove 52 are formed to penetrate in the cross diametrical direction, and the first through holes 53 are formed in annular grooves 54 formed on the outer periphery thereof. Through the first pressure receiving chamber 44.

On the other hand, the second oil passage 50 is formed by bending the cylinder head 27 and one side in the axial direction of the camshaft 22 and inside the sleeve 29 into an L-shape.
9 and communicates with the second pressure receiving chamber 45.

The electromagnetic switching valve 48 is a normal four-port two
It is of a position type, in which a solenoid, a passage component, a spool valve and the like are housed, a drain passage 56 communicating with an oil pan 55 is connected, and an oil main gallery is connected to an oil pump 57. 58. Also, this electromagnetic switching valve 48
The switching is controlled by a controller 59 that detects the engine operating state. That is, the oil main gallery 58 communicates with the first oil passage 49 or the second oil passage 50 according to the engine speed and the load, and the second oil passage 50 or the first oil passage 49 communicates with the drain passage 56 as appropriate. Control to be performed. In a predetermined rotation range such as a middle rotation, each of the oil passages 49,
By controlling the opening amount such as 50, the hydraulic pressure supply / discharge amount of each pressure receiving chamber 44, 45 is appropriately adjusted.

Therefore, according to this embodiment, for example, in the low-speed low-load range after the engine is started, the controller 5
9 outputs a control signal to the electromagnetic switching valve 48 to operate it, thereby connecting the oil main gallery 58 to the second oil passage 50 and, at the same time, connecting the first oil passage 49 to the drain passage 56.
For this reason, the piston 42 is pressed leftward by the high oil pressure supplied to the second pressure receiving chamber 45 as shown in FIG. 1, and holds the entire cylindrical gear 39 at the maximum leftward (forward) position. For this reason, the relative rotation phase between the timing sprocket 21 and the camshaft 22 is maintained in a state of being converted to one side via each tooth, and the closing timing of the intake valve is retarded.

When the engine shifts from the low-speed low-load range to the high-speed high-load range, the oil switching valve 48 connects the oil main gallery 58 to the first oil passage 49 and the second oil passage 50. And the drain passage 56 communicate with each other. Therefore, the oil pressure in the second pressure receiving chamber 45 is returned to the oil pan 55 through the drain passage 56 via the second oil passage 50, while the high oil pressure flowing into the first oil passage 49 is reduced by the passage hole 51, the annular shape. The first pressure receiving chamber 4 passes through the groove 52, the through hole 53, and the annular groove 54.
4, the pressure in the first pressure receiving chamber 44 becomes high. Therefore, the cylindrical gear 39 moves rightward (rearward) until the piston 42 of the rear gear component 39b hits the snap ring 26. Therefore, the relative rotation phase between the timing sprocket 21 and the camshaft 22 is converted to the other side, and the closing timing of the intake valve is advanced.

In the present embodiment, the outer diameter of the piston 42 can be formed sufficiently larger than that of the conventional example with the increase in the diameter of the rear end portion 23a of the cylindrical main body 23.
The pressure receiving area for the hydraulic pressures of 4, 45 increases. Therefore, the mobility of the piston 42 due to the hydraulic pressure supplied into each of the pressure receiving chambers 44 and 45, that is, the moving speed of the cylindrical gear 39 is increased, and the responsiveness of the valve timing control according to the change in the engine operating state is improved. .

In the maximum rightward movement position of the piston 42, only the outer peripheral portion of one end surface abuts against one side surface of the snap ring 26, and the entire end surface of the sleeve
Because there is no close contact with the inner end face of the large-diameter portion 29a, there is no hindrance to the leftward mobility.

Further, since the snap ring 26 restricts the free movement of the cylindrical main body 23 to the right,
External teeth 39d of the cylindrical gear 39 and inner teeth 2 of the cylindrical main body 23
Pressure contact of each tooth side with 3c is avoided, and an increase in the moving wear resistance of the cylindrical gear 39 can be suppressed. Moreover, since the snap ring 26 is detachable, the work of assembling the cylindrical gear 39 into the cylindrical main body 23 becomes easy.

According to this embodiment, a part of the first oil passage 49 is constituted by the passage hole 51, and the outer peripheral surface of the bolt head 30a, the inner peripheral surface 34a of the fitting hole 34, and the cylindrical portion 36 are formed. Inner end surface 36a and bottom surface 34b of fitting hole 34
The seal is double-sealed by the close contact seals and the seal ring 38 between both peripheral surfaces, so that the sealing performance is further improved, and the leakage of hydraulic pressure from between the bolt head 33 and the fitting hole 34 is reliably prevented. You. Therefore, the first pressure receiving chamber 44
Supply of hydraulic pressure to the cylindrical gear 39
Responsiveness is improved. In particular, since the hydraulic path directly communicates with the pressure receiving chamber 44 from the column portion 36, pressure loss to the first pressure receiving chamber 44 can be suppressed. As a result, the movement response of the cylindrical gear 39 is further improved.

Further, since the head 30a of the fixing bolt 30 is inserted and arranged in the insertion hole 34 of the sleeve 29, and the entire fixing bolt 30 is closer to the camshaft 22, the coupling strength of the sleeve 29 to the camshaft 22 is increased. And the inclination of the entire device including the timing sprocket 21 and the like in the radial direction can be suppressed.

Each of the pressure receiving chambers 4 before and after the piston 42
Since the hydraulic pressure is applied relatively to 4, 45, the cylindrical gear 39 can be held at an arbitrary moving position, and the control accuracy of the valve timing according to the change in the engine operating state is improved.

It should be noted that the present invention is not limited to the configuration of the above-described embodiment, and may have another structure instead of the cylindrical gear 39 as the phase conversion means. It is also possible to provide a projection on the inner peripheral surface of the cylindrical main body 23.

[0036]

As is apparent from the above description, according to the valve timing control apparatus of the present invention, the outer diameter of the piston can be set larger with the increase in the diameter of the rear end of the cylindrical body. The area is enlarged, and therefore, the moving speed of the phase conversion means is increased. As a result, the control responsiveness of the valve timing according to the change in the engine operation state is improved.

According to the second aspect of the present invention, since the free movement of the rotating body in the thrust direction can be regulated by the regulating member, the mobility of the phase conversion means between the rotating body and the sleeve is not affected, and is always maintained. Smooth mobility can be secured.

According to the third aspect of the present invention, since the regulating member is constituted by a detachable snap ring, the workability of assembling each component is improved, and the work efficiency can be improved.

According to the fourth aspect of the present invention, since the movement position of the phase conversion means is controlled by the hydraulic pressure in the two pressure receiving chambers before and after the piston, valve timing control accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional valve timing control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 ... Timing sprocket (rotating body) 22 ... Camshaft 23 ... Cylindrical main body 23a ... Rear end part 23b ... Front end part 23c ... Inner tooth 26 ... Snap ring (restriction member) 29 ... Sleeve 29a ... Large diameter part (support part) 30 ... fixing bolt 33 ... seal ring 42 ... piston 44, 45 ... pressure receiving chamber 47 ... hydraulic circuit

Claims (4)

[Claims] A rotating shaft driven by an engine; a camshaft having a cam for operating an intake / exhaust valve by a rotating force transmitted from the rotating body; a camshaft fixed to one end of the camshaft; A sleeve inserted through the cylindrical main body of the body, and interposed between the sleeve and the cylindrical main body, and converts the relative rotational phase between the rotating body and the camshaft by moving in the camshaft axial direction. A phase conversion means, a pressure receiving piston integrally provided at a rear end of the phase conversion means, and a pressure receiving chamber defined at least on a front end side of the piston to supply and discharge a hydraulic pressure to connect the phase conversion means to the camshaft shaft. A drive mechanism for moving the tubular body in a direction, wherein a rear end of the tubular body is formed to have a larger diameter than a front end, and the tubular body is provided at a rear end of the sleeve. The outer diameter of the support portion that rotatably supports the rear end side is formed to have a large diameter in accordance with the inner diameter of the rear end portion of the cylindrical main body, and the outer diameter of the piston is formed substantially equal to the outer diameter of the support portion. A valve timing control device for an internal combustion engine. 2. A restricting member for restricting free movement in the thrust direction of the cylindrical main body via a support portion of the sleeve is provided on an inner periphery of a rear end portion of the cylindrical main body. Valve timing control device for an internal combustion engine. 3. The valve timing control device for an internal combustion engine according to claim 2, wherein said regulating member is constituted by a snap ring which is detachable from a cylindrical main body. 4. The valve timing control device for an internal combustion engine according to claim 1, wherein pressure receiving chambers are formed before and after said piston.