Valve Timing Adjusting Device

Abstract

A valve timing adjusting device includes a first rotor rotating integrally with a crankshaft; a second rotor secured integrally with an intake or exhaust camshaft; a first hole formed passing through radially to a shoe formed inside the first rotor; a second hole formed through the shoe, intersecting the first hole; a coil spring pressing a lock pin received in the first hole to thereby engage the lock pin into a concavity formed on the outer peripheral surface of the second rotor; and a shaft inserted into the second hole in order to prevent the coil spring from dashing out.

Description

TECHNICAL FIELD

The present invention relates to a valve timing adjusting device controlling the open and close timing of an intake valve or exhaust valve of an internal combustion engine such as an engine (hereinafter referred to as an “engine”).

BACKGROUND ART

A conventional valve timing adjusting device includes a first rotor that integrally secures a case inside having a plurality of projecting shoes and forming an oil pressure chamber between those shoes, a front cover, and a rear cover, both covering those oil pressure chambers, and that rotates integrally with a crank shaft; and a second rotor that has a plurality of vanes each dividing each of those oil pressure chambers into an advanced-side oil pressure chamber and a retarded-side oil pressure chamber, can relatively rotate by a predetermined angle within the first rotor, and is secured integrally with an intake or exhaust camshaft, wherein the hydraulic pressure of an oil pump assuming charge of supplying oil to a sliding section of an engine is supplied and exhausted, and the hydraulic pressure controls the relative position of the second rotor with respect to the first rotor.

In the above-mentioned structure, in the absence of hydraulic force within the oil pressure chambers when the engine is started, the shoes of the first rotor and the vanes of the second rotor repeatedly abut against and separate from each other, thereby producing slapping sounds. For this reason, the production of slapping sounds is suppressed by providing a first hole passing through radially to the shoe; pressing a lock pin received in the first hole with a coil spring inserted in the hole, to engage the lock pin into a concavity provided on the outer peripheral surface of the second rotor when the second rotor assumed the most retarded position, for example; and thereby, locking the relative position between the first rotor and the second rotor. Note that the lock pin is moved in a releasing direction by hydraulic force against urging force induced by the coil spring. When the lock pin is moved, the back pressure behind the lock pin is exhausted outside.

In such a case, a lock structure for preventing the coil spring from dashing or jumping out is required. Conventionally, the following four types are provided for the lock structure.

The first lock structure, when the coil spring is locked against dashing out movement with a stopper, which is a cylinder member, inserted in a lock pin receiving hole from outside radially to the device, secures the stopper with a shaft inserted along the direction orthogonal to the lock pin receiving hole. However, according to the structure, the diameter of a shaft receiving hole formed along the direction orthogonal to the lock pin receiving hole becomes small. This requires the shaft receiving hole to be specially machined. For this reason, the number of production processes increases, which incurs an increase in cost. Moreover, the structure needs two parts, the stopper and the shaft to lock the coil spring so as not to dash out.

The second one, as shown in Patent Document 1, when the coil spring is locked so as not to dash out by inserting a plate-shaped stopper into a groove formed along the direction orthogonal to the lock pin receiving hole, requires high machining accuracy for machining the groove. Besides, the structure is difficult in assembly because the plate-shaped stopper is inserted into the groove after the insertion of the lock pin and the coil spring into the receiving hole from outside radially to the device.

The third lock structure, in which the coil spring is locked against dashing out movement by a stopper press-fitted into the lock pin receiving hole from outside radially to the device, might dislodge the stopper therefrom because of centrifugal force in a high revolution area and might dislodge the stopper due to looseness from vibrations. Furthermore, the structure needs production control for the press fit force and the press fit size of the stopper.

The fourth structure, as shown in Patent Document 2, where the coil spring is locked for preventing its dashing-out movement by means of the wall surface of a groove provided on a case, is difficult in assembly because the coil spring has to be inserted, together with the lock pin, into a retracting groove under compressed conditions.

Patent Document 1: JP-A-11-101107

Patent Document 2: JP-A-2005-002952

The conventional valve timing adjusting devices are arranged as mentioned above. Accordingly, various lock structures for locking the coil spring so as not to dash out are used for the device; however, those lock structures have shortcomings: need for high machining accuracy, difficulty in assembly, the dislodgement of the stopper due to centrifugal force in a high revolution area and the dislodgement of the stopper caused by looseness from vibrations, and necessity for production control for the press-fit force and the press-fit size of the stopper, respectively.

The present invention has been made to solve the above-mentioned problems. An object of the present invention is to provide a valve timing adjusting device loosening working accuracy requirements, improving workability and assembling, and employing a locking member with a simple shape to be easily manufactured.

DISCLOSURE OF THE INVENTION

The valve timing adjusting device according to the present invention includes a first rotor that integrally secure a case inside having a plurality of projecting shoes and forming an oil pressure chamber between those shoes, a front cover, and a rear cover, both covering those oil pressure chambers, and that rotates integrally with a crank shaft; a second rotor that has a plurality of vanes each dividing each of the oil pressure chambers into an advanced-side oil pressure chamber and a retarded-side oil pressure chamber, is able to relatively rotate by a predetermined angle within the first rotor, and is secured integrally with an intake or exhaust camshaft; a hydraulic pressure supply and exhaust means capable of supplying working fluid to and exhausting it from the advanced-side oil pressure chambers and the retarded-side oil pressure chambers; a first hole passing through the shoe radially to the device; a second hole formed through the shoe, intersecting the first hole; a coil spring pressing a lock pin received in the first hole to thereby engage the lock pin into a concavity provided on an outer peripheral surface of the second rotor; and a shaft inserted into the second hole in order to prevent the coil spring from dashing out.

According to the present invention, it is arranged such that the coil spring is locked against dashing out movement by the shaft inserted into the second hole provided intersecting the first hole receiving the lock pin and the coil spring. This enables the hole where the shaft is inserted to have a size near to the diameter of the lock pin receiving hole, permits the hole where the shaft is inserted to be died, and eliminates the requirement of machining the hole by machining. As a result, this provides a valve timing adjusting device excellent in forming. Further, the hole having a larger diameter to be inserted by the shaft can achieve loosened dimensional accuracy requirements to improve workability and assembling, and further permits the shaft to have a simple shape of a virtually cylindrical configuration, thereby facilitating the manufacture of the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an internal structure of a valve timing adjusting device according to the first embodiment of the present invention, and is a longitudinal sectional view when a second rotor is located at the most retarded position.

FIG. 2 is a transverse sectional view along the line A-A of FIG. 1.

FIG. 3 is a longitudinal sectional view along the line B-B of FIG. 2.

FIG. 4 is a longitudinal sectional view of the valve timing adjusting device when the second rotor is located at the most advanced position.

FIG. 5 is an enlarged transverse sectional view of essential parts showing a state where the second rotor is locked.

FIG. 6 is an enlarged longitudinal sectional view of essential parts showing a state where the second rotor is locked.

FIG. 7 is an enlarged transverse sectional view of essential parts showing a state where the second rotor is lock-released.

FIG. 8 is an enlarged longitudinal sectional view of essential parts showing a state where the second rotor is lock-released.

FIG. 9 is an enlarged transverse sectional view of essential parts showing a state where a lock pin and a coil spring are assembled.

FIG. 10 is an enlarged transverse sectional view of essential parts explaining why the second rotor cannot rotate relatively to the first rotor.

FIG. 11 is an enlarged longitudinal sectional view of essential parts explaining why the second rotor cannot be assembled to the first rotor.

FIG. 12 is an enlarged longitudinal sectional view of essential parts showing a state where a cylinder shaped shaft and a stepped cylinder shaped lock pin are assembled.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will now be described with reference to the accompanying drawings in order to explain the present invention in more detail.

First Embodiment

The drawings are views of the internal structure of a valve timing adjusting device according to the first embodiment of the present invention; FIG. 1 is a longitudinal sectional view of the valve timing adjusting device when a second rotor is located at the most retarded position; FIG. 2 is a transverse sectional view along the line A-A of FIG. 1; FIG. 3 is a longitudinal sectional view along the line B-B of FIG. 2; and FIG. 4 is a longitudinal sectional view of the valve timing adjusting device when the second rotor is located at the most advanced position.

As shown in FIG. 1 to FIG. 4, the valve timing adjusting device 1 according to the first embodiment is generally composed of a first rotor 1 rotating synchronously with a crankshaft (not shown) of an engine (not shown) through a chain (not shown) and a second rotor 3 provided within the first rotor 1 and secured integrally with the end face of an intake or exhaust camshaft (hereinafter referred to as a camshaft).

The first rotor 1 is generally composed of a case 4 that has outside a sprocket 4a receiving a rotational driving force of the crankshaft (not shown) and has inside a plurality of shoes 4b inwardly projecting radially to the device, a front cover 5, and a rear cover 6, both covering the internal space of the case 4. Those three components are integrally fastened to each other with a bolt 7.

The second rotor 3 is composed of a boss 10a fastened integrally with the end face of the camshaft 2 through a washer 8 with a bolt 9, and a rotor 10 having a plurality of vanes 10b outwardly projecting, radially to the device, from the outer periphery of the boss 10a. The vanes 10b of the rotor 10 partitions a plurality of internal spaces formed by the shoes 4b of the case 4 into an advanced-side oil pressure chamber 11 supplied with hydraulic pressure when the rotor 10 is relatively rotated in the direction of the advanced-side with respect to the first rotor 1 and a retarded-side oil pressure chamber 12 supplied with hydraulic pressure when the rotor 10 is relatively rotated in the retarded-side direction with respect to the first rotor. The advanced-side oil pressure chambers communicate with advanced-side oil passages 13 supplying hydraulic pressure thereto and exhausting it therefrom, and the retarded-side oil pressure chambers communicate with retarded-side oil passages 14 supplying hydraulic pressure thereto and exhausting it therefrom.

A receiving hole (first hole) 15 is formed in the shoe 4b of the case 4a, and passes through the shoe radially to the device. In the receiving hole 15, a nearly cylindrical lock pin 16 that is reciprocally slidable radially to the device is inserted from outside radially thereto and disposed therein. Moreover, a nearly cylindrical hole (second hole) 4b-1 is formed in the shoe 4b in the direction (axially to the rotor 10) orthogonal to the receiving hole 15, and a nearly cylindrical shaft 17 inserted into the hole 4b-1 locks the rear end of a coil spring 18 inserted into the receiving hole 15 so as to press the lock pin 16 and the rear end of the lock pin 16.

The diameter of the shaft 17 is designed smaller than the diameter of the receiving hole 15 of the lock pin 16, and further, smaller than the diameter of the coil spring 18. In addition, when the shaft 17 is formed with a D-shaped cross section, the position of the bearing surface having the D-shaped cross section can be changed either opposed or not-opposed to the coil spring 18, depending on the assembly direction of the shaft 17.

When the relative position of the rotor 10 with respect to the case 4 is at the most retarded position, an engaging concavity 19 is formed on the outer periphery of the boss 10a of the rotor 10, and engaged with the tip of the-lock pin 16 that is inwardly advanced radially to the device by urging force from the coil spring 18. Besides, the engaging concavity 19 communicates with a release oil passage 20.

The operation will now be described below.

First, when the relative position of the rotor 10 with respect to the case 4 is located at the most retarded position shown in from FIG. 1 to FIG. 3, FIG. 5, and FIG. 6, the lock pin 16 is engaged with the engaging concavity 19 by urging force from the coil spring 18 (lock pin engaging state). From that state, when the hydraulic pressure is supplied to the engaging concavity 19 through the release oil passage 20 to pressurize the lock pin tip 16a, the lock pin 16 outwardly slides radially to the device within the lock pin receiving hole 15 against the urging force from the coil spring 18, and is released from the engaging concavity 19. At that time, oil existing on the back pressure side of the lock pin is exhausted from a clearance provided between the lock pin receiving hole 15 and the shaft 17. As shown in FIG. 7 and FIG. 8, as released from the lock pin 16, the rotor 10 can relatively rotate in the advanced-side direction as shown in FIG. 4 in such a manner that the advanced-side oil pressure chamber 11 is supplied inside with oil through the advanced-side oil passage 13 and oil existing in the retarded-side oil pressure chamber 12 is exhausted through the retarded-side oil passage 14.

On the other hand, when the relative position of the rotor 10 with respect to the case 4 is at an advanced position, the retarded-side oil pressure chamber 12 is supplied with oil through the retarded-side oil passage 14 and oil existing in the advanced-side oil pressure chamber 11 is exhausted through the advanced-side oil passage 13; thus, the rotor rotates relatively in the retarded-side direction. When the relative position of the rotor 10 with respect to the case 4 rotates to the most retarded position, the lock pin 16 inwardly slides radially thereto within the lock pin receiving hole 15 by urging force from the coil spring 18, and engages with the engaging concavity 19.

As mentioned above, according to the first embodiment, it is arranged such that the hole having a diameter approximating to the diameter of the receiving hole receiving the lock pin and the coil spring is formed through the shoe with intersecting the receiving hole, and is inserted the substantially cylindrical shaft into the hole, to thereby lock the coil spring against dashing out movement. This enables the hole to be inserted by the shaft to be manufactured in a large diameter by dieing, and also enables the hole to be formed at one time when the case is manufactured by forging or the like. Therefore, the hole-opening process by machining is eliminated, which achieves reduced manufacturing cost thereof. It should be noted that since a substantially cylindrical or simple shaped one can be employed for the above shaft, it can be manufactured at one time by forging or the like without any-machining processes. As a result, the production cost can be reduced, loosened dimensional accuracy can be achieved, and further workability and assembling can be improved.

Second Embodiment

FIG. 9 is a traverse sectional view of essential parts showing the second embodiment. It is arranged such that the diameter of the shaft 17 is smaller than the diameter of the lock pin receiving hole and the diameter of the coil spring 18. Such arrangement of the device enables the coil spring 18 to be inwardly compressed radially to the device by using a U-shaped assembly tool 21, having a forked piece 21a passing through a clearance 22 formed between the lock pin receiving hole 15 and the shaft 17. As a result, the shaft 17 can be easily inserted into the hole 4b-1, which is formed axially to the device, thereby performing improved assembling capacity. It will be appreciated that after completion of the assembly, when the assembly tool 21 is detached therefrom, the clearance 22 provided between the lock pin receiving hole 15 and the shaft 17 serves as a drain hole or a drain groove for exhausting oil to the back pressure side of the lock pin.

Third Embodiment

As is shown for example in the drawings, the shaft 17 is designed, e.g., in a D-shaped cross section so as to have at least one plane bearing surface 17a receiving the coil spring axially to the shaft on its outer peripheral surface. The dimensions thereof are designed such that, if a circular arc surface of the shaft 17 is opposed to the end face of the lock pin because of the wrong assembly direction of the shaft 17, the end face of the lock pin abuts against the circular arc face of the shaft 17 and thereby, the front end of the lock pin always projects from the inner periphery of the case 4 before the lock pin is completely received in the receiving hole 15. Consequently, since as shown in FIG. 11 the rotor 10 cannot be inserted in the direction indicated by the arrow, or as shown in FIG. 10 the rotor 10 cannot rotate, the assembly proves to be improper, which enables the positive prevention of delivery of incorrectly assembled products.

On the other hand, when the D-shaped plane section 17a of the shaft 17 is opposed to the end face of the lock pin 16, the D-shaped plane section 17a of the shaft 17 compresses the coil spring 18 to make the lock pin 16 project from the receiving hole 15. However, since the dimensions are designed such that the lock pin 16 can be completely pushed into the receiving hole 15 before the end face of the lock pin abuts against the D-shaped plane section 17a of the shaft 17, the device can normally operate.

Note that some inclination of the plane section 17a of D-shape of the shaft 17 with respect to the sliding direction of the coil spring 18 is corrected in such a manner that the shaft 17 is rotated within the shaft inserting hole because the bearing surface of the coil spring 18 or the lock pin 16 directly presses the shaft 17.

Fourth Embodiment

FIG. 8 is a view showing the fourth embodiment. On either or both of the front cover 5 and the rear cover 6 against which the end of the shaft 17 abuts (in FIG. 8, only on the front cover 5), a positioning concavity 5a engaged with the end of the shaft is formed. For instance, when the shaft 17 has a D-shaped cross section, this arrangement enables the prevention of incorrect assembly of the shaft 17 by forming the positioning concavity 5a also having a D-shaped cross section, and enables the prevention of rotation of the shaft 17 caused by vibrations.

Fifth Embodiment

FIG. 12 is a traverse sectional view of essential parts showing the fifth embodiment. The shaft 17 is designed in the shape of a cylinder, and the lock pin 16 is designed in the shape of a stepped cylinder. The coil spring 18 is provided around the small diameter section of the lock pin; one end of the bearing surface thereof abuts the circular arc surface of the shaft 17, while the other end thereof abuts the stepped section of the lock pin 16. Moreover, the end face of the small diameter section side of the lock pin 16 is caused to abut against the circular arc surface of the shaft at the time of release of the lock pin to prevent the coil spring from sticking.

Since such an arrangement enables the diameter of the coil spring to be substantially the same as the diameter of the receiving hole, the receiving hole 15 serves as a guide at the time of contraction and expansion of the coil spring, and thereby, acts as a preventer against inclination.

It should be noted that if the bearing surface of the coil spring 18 abuts on a circular arc surface of the shaft 17 as in the case of the fifth embodiment, the bearing surface section of the coil spring may be twofold or threefold wound in order to prevent deformation of the bearing surface thereof.

INDUSTRIAL APPLICABILITY

As mentioned above, the present invention is able to be widely applied to a valve timing adjusting device employing a locking member excellent in workability and assembling, installed in an engine and so on.

Claims

1. A valve timing adjusting device comprising: a first rotor that integrally secures a case inside having a plurality of projecting shoes and forming oil pressure chambers between those shoes, a front cover, and a rear cover, both covering the oil pressure chambers, and that rotates integrally with a crank shaft;a second rotor that has a plurality of vanes each dividing each of the oil pressure chambers into an advanced-side oil pressure chamber and a retarded-side oil pressure chamber, is able to relatively rotate by a predetermined angle within the first rotor, and is secured integrally with an intake or exhaust camshaft;a hydraulic pressure supply and exhaust means capable of supplying working fluid to and exhausting it from the advanced-side oil pressure chambers and the retarded-side oil pressure chambers;a first hole passing through the shoe radially to the device;a second hole formed through the shoe, intersecting the first hole;a coil spring pressing a lock pin received in the first hole to thereby engage the lock pin into a concavity provided on an outer peripheral surface of the second rotor; anda shaft inserted into the second hole in order to prevent the coil spring from dashing out.

2. The valve timing adjusting device according to claim 1, wherein the diameter of the shaft is smaller than the diameter of the first hole.

3. The valve timing adjusting device according to claim 1, wherein the diameter of the shaft is smaller than the diameter of the coil spring.

4. The valve timing adjusting device according to claim 1, wherein the shaft has a plane bearing surface receiving the coil spring on a part of its outer peripheral surface.

5. The valve timing adjusting device according to claim 4, wherein the shaft has a D-shaped cross section.

6. The valve timing adjusting device according to claim 1, wherein a positioning concavity is formed on either or both of the front cover and the rear cover on which the end of the shaft abuts.

7. The valve timing adjusting device according to claim 1, wherein the shaft is at one time formed by forging.