JPH08144720A - Valve timing control device for internal combustion engine - Google Patents

Abstract

PURPOSE: To provide a valve timing control device for an internal combustion engine which can eliminate backrush of helical spline meshing portions with a simple structure. CONSTITUTION: First and second spools 8, 9 are arranged between a housing 7 formed on a sprocket 5 and a sleeve 3 installed on a cam shaft 1, and helical spline connected with each other. A first pressure chamber 12 is formed in front side of the housing 7 for applying hydraulic pressure to the first spool 8 by means of a packing 10 of the first spool 8. A second pressure chamber 13 is formed in rear side of the housing 7 for applying hydraulic pressure to the second spool 9 by means of a packing 11 of the second spool 9. A third pressure chamber 17 formed between the packings 10 and 11 is opened to atmosphere through a discharge port 18 formed on a peripheral wall of the housing 7.

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 / closing timing of intake / exhaust valves of an internal combustion engine.

[0002]

2. Description of the Related Art For example, in engines of automobiles,
It is effective to provide a valve timing control device as a means for increasing output and improving fuel efficiency. The valve timing control device is for variably controlling the opening / closing timing of intake / exhaust valves according to the operating state of the engine.

As one example thereof, there is one in which a spool is interposed between a housing provided on a pulley that is rotated in synchronization with the rotation of an engine and a cam shaft for driving a valve. An outer spline provided on the outer circumference of the spool meshes with a spline provided on the inner circumference of the housing. An inner spline provided on the inner circumference of the spool meshes with a spline provided on the outer circumference of the camshaft. Due to this meshing, the driving force of the pulley is transmitted to the cam shaft via the spool.

At least one of the housing and the spool or the spool and the cam shaft is in helical spline engagement. Pressure chambers are formed in front of and behind the spool, and the spool is moved in the axial direction of the camshaft by controlling the hydraulic pressure of the hydraulic oil supplied to each pressure chamber in accordance with the operating state of the engine. By the action of the helical spline, they are simultaneously rotated in the twisting direction. As a result, the relative rotational phase of the camshaft with respect to the pulley is shifted, and the opening / closing timing of the valve is adjusted.

However, there is backlash in the meshing portion of the helical spline. As a result, when the cam shaft changes in rotation due to the change in cam driving torque, there is a problem that abnormal noise or vibration occurs due to beating between the teeth forming the helical spline.

Conventionally, in order to solve such a problem, for example, there is one disclosed in Japanese Patent Laid-Open No. 63-131808. That is, the spool is composed of a first spool and a second spool, which are divided into two in a direction perpendicular to the axis of the spool. Splines are formed on the inner and outer peripheral surfaces of both spools, and are engaged with the splines of the camshaft and the housing. Further, a seal member that seals the outer peripheral surface of the second spool located on the rear side in the housing with the inner peripheral surface of the housing is provided, and pressure chambers are formed before and after the seal portion of the second spool. ing. Therefore, by controlling the hydraulic pressure in one of the pressure chambers to be high, the second spool is positively moved along the axial direction of the camshaft.

The first spool is connected by a connecting pin inserted into the second spool via the first spool and a coil spring interposed between the connecting pin and the first spool. By biasing the first and second spools toward each other in the proximity direction by the coil spring, the tooth traces of both spools are displaced to eliminate backlash at the helical spline meshing portion.

[0008]

However, in the above-mentioned prior art, in order to eliminate backlash, a biasing means such as a connecting pin and a coil spring is required.
The number of parts increased and the device structure became complicated, leading to an increase in manufacturing cost.

The present invention has been made in view of the problems existing in the above-mentioned prior art, and its object is a valve of an internal combustion engine capable of eliminating backlash at a helical spline meshing portion with a simple structure. It is to provide a timing control device.

[0010]

In order to achieve the above-mentioned object, in the invention of claim 1, the spool is a first spool formed in the front side in the housing and on which a hydraulic pressure of a first pressure chamber acts. , A second spool which is also formed on the rear side and on which the hydraulic pressure of the second pressure chamber is applied, and the inner and outer peripheral surfaces of both spools have an inner side and an inner side meshed with the splines of the camshaft and the housing, respectively. A valve timing control device for an internal combustion engine, wherein outer splines are formed, and further, both spools are provided with seal members for sealing oil from pressure chambers to which they correspond.

According to the second aspect of the present invention, the space formed between the first spool and the second spool is open to the atmosphere through a discharge hole formed through the wall of the housing.

[0012]

In the invention of claim 1 having the above-mentioned structure, the first and second spools are provided with seal members for sealing the hydraulic oil from the first and second pressure chambers, respectively. Therefore, the hydraulic pressure of the first pressure chamber is applied to the first spool, and the hydraulic pressure of the second pressure chamber is applied to the second spool. By controlling the hydraulic pressure of both pressure chambers, both spools are moved.

Hydraulic pressure is applied to both spools in a direction in which they approach each other, and the tooth traces of the helical spline of the spools pushed by the hydraulic pressure are displaced.
As a result, backlash at the spline meshing portion is eliminated, and vibration and noise due to gear ratcheting due to cam fluctuation torque can be prevented.

In the second aspect of the invention, since the space formed between the first spool and the second spool is at atmospheric pressure, a force against the pressure in the first and second pressure chambers does not occur, The backlash-free state can be maintained even when the cam fluctuation torque is large.

[0015]

First Embodiment A first embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a camshaft 1 for driving an intake valve is supported by a cylinder head 2 of an engine serving as an internal combustion engine, and is in the front-rear direction (refers to the left-right direction on the paper surface. Side, the right side as the rear side). The flange portion 1α is provided on the outer peripheral surface of the camshaft 1 near the cylinder head 2.

The cylindrical sleeve 3 is fitted onto the tip of the cam shaft 1 and is fixed by bolts 4. Helical spline 3α is sleeve 3
It is formed on the outer peripheral surface on the rear side.

The sprocket 5 as a rotating body is fitted on the outer periphery of the front portion of the camshaft 1 by means of a cylindrical boss portion 5α formed at the center thereof. The front end surface of the boss portion 5α is in contact with the rear end surface of the sleeve 3, and the rear end surface is in contact with the flange portion 1α of the camshaft 1, so that the sprocket 5 is connected to the sleeve 3 and the flange portion 1α. Held in between.

The chain 6 is hung between the sprocket 5 and a sprocket attached to a crankshaft of an engine (not shown), and the rotation of the crankshaft is transmitted to the sprocket 5 via the chain 6. It

The housing 7 is integrally formed on the front side surface of the sprocket 5 so as to surround the camshaft 1, and the space surrounded by the inner peripheral surface of the housing 7 and the front side surface of the sprocket 5 forms an annular space K. ing. The helical spline 7α is formed at the center of the inner peripheral surface of the housing 7.

The spools 8 and 9 are arranged in the annular space K. That is, the first spool 8 having a cylindrical shape is fitted onto the outer peripheral surface of the front portion of the sleeve 3 with the sliding portion 8α provided around the front portion thereof. Also,
A seal accommodating groove 8β is provided in the outer peripheral surface of the sliding portion 8α so as to be recessed along the circumferential direction. The packing 10 as a seal member is housed in the housing groove 8β, and the outer peripheral surface of the first spool 8 and the front inner peripheral surface of the housing 7 are sealed. The inner helical spline 8γ is the first spool 8
The spline 3α of the sleeve 3 is formed on the inner peripheral surface of the rear part.
Is meshed with the front side of. Outer helical spline 8
δ is formed on the outer peripheral surface of the rear portion of the first spool 8 and meshes with the front side of the spline 7α of the housing 7.

The second spool 9 having a cylindrical shape is disposed at the rear of the first spool 8, and the outer peripheral surface of the boss portion 5α of the sprocket 5 is formed by the inner peripheral surface of the sliding portion 9α provided around the rear portion thereof. Is fitted on. On the outer peripheral surface of the sliding portion 9α, a seal accommodating groove 9β is recessed along the circumferential direction. The packing 11 is housed in the housing groove 9β,
The outer peripheral surface of the second spool 9 and the rear inner peripheral surface of the housing 7 are sealed. The inner helical spline 9γ is formed on the inner peripheral surface of the front portion of the second spool 9, and the sleeve 3
Is engaged with the rear side of the spline 3α. The outer helical spline 9δ is formed on the outer peripheral surface of the front part of the second spool 9 and meshes with the rear side of the spline 7α of the housing 7.

As mentioned above, the first and second spools 8,
By interposing 9 between the sleeve 3 and the housing 7, the rotational force of the crankshaft transmitted to the sprocket 5 rotationally drives the camshaft 1 via the spools 8 and 9 and the sleeve 3.

The annular space K is divided by the sliding portions 8α and 9α of the first and second spools 8 and 9, respectively, and the space on the front side from the sealing portion of the packing 10 of the first spool 8 has the first pressure. It is a room 12. Further, the space on the rear side from the seal portion of the second spool 9 by the packing 11 is a second pressure chamber 13. The first pressure chamber 12 is communicated with an advance angle control passage 14 formed through the bolt 4 and the center of the camshaft 1. In addition, the second pressure chamber 13 has the boss portion 5 of the sprocket 5.
The advance angle control passage 14 formed through the α and the camshaft 1 is communicated with a retard angle control passage 15 which is different from the advance angle control passage 14.

Further, in the annular space K, a third pressure chamber 17 is formed between the seal portions defined by the packings 10 and 11 that divide the pressure chambers 12 and 13. The discharge hole 18 is formed through the peripheral wall of the housing 7, and the third pressure chamber 17 is opened to the atmospheric pressure through the discharge hole 18.

The advance angle control passage 14 and the retard angle control passage 15 are connected to an oil control valve (hereinafter referred to as OCV) 16. The OCV 16 has a switching valve, a relief valve, etc., which are not shown, and has an oil passage switching function and a pressure adjusting function. And the same OC
V16 is connected to an oil pan 20 via an oil pump 19. The oil pump 19 is connected to the crankshaft and pumps up the hydraulic oil in the oil pan 20 at all times during engine operation. The hydraulic oil pumped up by the oil pump 19 is supplied to the pressure chambers 12 and 13 via the OCV 16 and the advance control passage 14 or the retard control passage 15.

A control device 21 is connected to the OCV 16, and the control device 21 changes the supply pressure of the hydraulic oil to the first and second pressure chambers 12 and 13 according to the operating state of the engine. By the variable control of the supply pressure of the hydraulic oil by the control device 21, a moving force in the cam shaft direction is applied to both spools 8 and 9.

In the third pressure chamber 17, a gap between the inner peripheral surface of the sliding portion 8α of the first spool 8 and the outer peripheral surface of the front portion of the sleeve 3 and the inner peripheral surface of the sliding portion 9α of the second spool 9 are provided. The hydraulic oil in the first and second pressure chambers 12 and 13 flows in through the gap between the surface and the outer peripheral surface of the boss portion 5α of the sprocket 5, respectively.

Now, the controller 21 controls the first pressure chamber 12
When the internal hydraulic pressure is controlled to be higher than that in the second pressure chamber 13, both spools 8 and 9 are moved rightward in FIG. 1 along the axis of the camshaft 1. Both spools 8, 9
At the same time as the movement of the sprocket, the sprocket 5 is rotated in the twisting direction due to the action of the helical meshing.

When the hydraulic pressure in the second pressure chamber 13 is controlled to be high, both spools 8 and 9 are moved leftward along the axis of the camshaft 1 in FIG. Then, the spools 8 and 9 are twisted in the opposite direction to the above,
The rotation phases of the camshaft 1 and the sprocket 5 are shifted in the retard direction, and the opening / closing timing of the intake valve is delayed.

When the two spools 8 and 9 are moved, the hydraulic pressure in the pressure chambers 12 and 13 having the lower hydraulic pressure is maintained at the atmospheric pressure or higher. By the way, when the valve opening / closing timing is changed, the rotation of the camshaft 1 varies. However, in this embodiment, the spools 8 and 9 are provided with packings 10 and 11 for sealing the hydraulic oil from the corresponding pressure chambers 12 and 13, respectively. Therefore, the pressure chambers 12, 1
A hydraulic pressure equal to or higher than the atmospheric pressure in 3 is applied to both spools 8 and 9, respectively, so that the spools are pressed against each other in the approaching direction. For this reason, the spools 8 and 9 are pressed against the helical splines in opposite directions, and the backlash at the spline meshing portion is eliminated. As a result, vibration and noise due to gear rattling due to the cam fluctuation torque can be prevented.

As described above, according to this embodiment, it is possible to eliminate the backlash at the spline meshing portion with a simple structure in which only the packings 10 and 11 as described above are provided. As a result, unlike the prior art, a biasing means such as a connecting pin or a coil spring for eliminating backlash is not required, and it is possible to prevent the device structure from becoming complicated and the manufacturing cost accompanying it to increase.

Further, the third pressure chamber 17 is open to the atmosphere via the discharge hole 18. Therefore, no repulsive force is generated by pressing the third pressure chamber 17. As a result, the hydraulic pressures acting on the spools 8 and 9 become forces to push each other as they are, and even when the cam fluctuation torque is large, it can be counteracted and the backlash of the spline meshing portions can be eliminated. Can hold

[0033]

[Second Embodiment] A second embodiment of the present invention will be described below with reference to the drawings. Only the differences from the first embodiment will be described.

As shown in FIG. 2, in this embodiment, the discharge hole 22 is formed so as to penetrate obliquely with respect to the thickness direction of the peripheral wall portion of the housing 7, and the teeth formed on the outer peripheral edge portion of the sprocket 5 are shown. It is opened toward 5β.

Therefore, with the movement of the spools 8 and 9, the hydraulic oil in the third pressure chamber 17 is discharged toward the teeth 5β of the sprocket 5, and oil is supplied to the meshing portion between the teeth 5β and the chain 6 meshing with the teeth 5β. Will be done. This refueling contributes to noise prevention and wear prevention of the chain 6 and the teeth 5β.

The following embodiments can be carried out without departing from the spirit of the present invention. (1) Embodying the present invention in a valve timing control device for an exhaust valve. (2) Only one of the housing 7 and the spools 8 and 9 or the spools 8 and 9 and the sleeve 3 is in helical spline engagement. (3) Do not provide the discharge hole 18. (4) A guide member such as a bent pipe material is provided in the outer opening of the discharge hole 18 of the first embodiment, and the discharge direction of the hydraulic oil is directed to the teeth 5β of the sprocket 5 by the guide member. .

The technical idea other than the claims that can be understood from the above-described embodiments will be described. (1) The rotating body is the sprocket 5, and the discharge hole 22
The valve timing control device for an internal combustion engine according to claim 2, wherein the opening is formed toward the tooth 5β of the sprocket 5.

By doing so, it is possible to contribute to reduction of drive noise of the chain 6 meshed with the sprocket 5 and prevention of wear of the meshed portion. (2) The discharge hole 18 and the sprocket 5 as a rotating body
The valve timing control device for an internal combustion engine according to claim 2, wherein a guide for guiding oil to the tooth 5β is provided between the valve 5 and the tooth 5β.

By doing so, oil is supplied to the meshing portion between the tooth 5β and the chain 6 that meshes with it, which contributes to noise prevention and wear prevention of the chain 6 and tooth 5β.

[0040]

According to the invention of claim 1 having the above-mentioned structure, a connecting pin for eliminating backlash of a spline meshing portion, a biasing means such as a coil spring, etc. are not required, and the apparatus structure becomes complicated and accordingly. It is possible to prevent an increase in manufacturing cost.

According to the second aspect of the present invention, the pressing force of the first and second spools is not reduced, and the backlash of the spline meshing portion is eliminated even when the cam fluctuation torque is large. Can hold.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a valve timing control device.

FIG. 2 is a view showing another example, which is an enlarged view of the vicinity of a discharge hole.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Camshaft, 3α ... Helical spline of sleeve as spline of camshaft, 5 ... Sprocket as rotating body, 5α ... Helical spline of sprocket, 7 ... Housing, 7α ... Helical spline of housing, 8 ... First spool, 8γ: inner helical spline, 8δ: outer helical spline, 9: second spool, 9γ: inner helical spline, 9δ: outer helical spline, 10, 11 ... packing as a sealing member.

Claims (2)

[Claims] 1. A camshaft for driving a valve, a rotary body connected to a crankshaft of an internal combustion engine and externally fitted to the camshaft, and provided on a side surface of the rotary body so as to rotate integrally with the rotary body. And a spool surrounding the camshaft, and a spool interposed between the rotating body and the housing in the housing, the camshaft and the spool, and the spool and the housing are spline-coupled, respectively, and at least A set of splines is composed of helical splines, and the hydraulic pressure acting on the front and rear of the spool is variably controlled according to the operating state of the internal combustion engine, and the spool is moved in the axial direction of the camshaft, thereby camming the rotor. Valve timing that controls the opening / closing timing of the valve by changing the rotation phase of the shaft In the control device, the spool is acted on by a first spool in which the hydraulic pressure of a first pressure chamber formed on the front side in the housing acts and by a hydraulic pressure in a second pressure chamber formed in the rear side of the housing. A second spool, and inner and outer splines meshed with the splines of the camshaft and the housing are formed on the inner and outer peripheral surfaces of both spools. A valve timing control device for an internal combustion engine, which is provided with a seal member for sealing oil from a chamber. 2. The valve for an internal combustion engine according to claim 1, wherein the space formed between the first spool and the second spool is open to the atmosphere through an exhaust hole formed through a wall of the housing. Timing control device.