JP2004300930A - Valve timing adjusting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve timing adjusting device capable of effectively preventing interference of an extended part 61 of an assist spring 6 and a spring end insertion through groove 75 provided on a bushing 7 and facilitating to form the bushing 7 out of sintered metal. <P>SOLUTION: The assist spring 6 energizing a vane rotor 2 to an advance side is provided between a shoe housing 1 and the vane rotor 2. The extended part 61 engages with an engagement pin 8 fixed to the shoe housing 1. An extended part 62 engages with the vane rotor 2. The assist spring 6 is stored in the bushing 7 having the spring end insertion through groove 75 which the extended part 61 is inserted through formed thereon. Since the engagement pin 8 includes a taper part 83 and the extended part 61 engages with the taper part 83 and is energized to a front side, interference of the bushing 7 and the spring end insertion through groove 75 can be prevented even under a twisted condition. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a valve timing adjusting device that adjusts the opening / closing timing (timing) of an intake valve (valve) or an exhaust valve (valve) of an internal combustion engine (engine) according to operating conditions.
[0002]
[Prior art]
The valve timing adjusting device includes a shoe housing that rotates with a crankshaft (drive shaft) of the engine, and a vane rotor that rotates with a camshaft (driven shaft). The vane rotor includes a vane that divides a recess formed in the shoe housing into an advance chamber and a retard chamber, and the vane rotor is moved relative to the shoe housing by a difference in hydraulic pressure supplied to the advance chamber and the retard chamber. And the camshaft is displaced to the advance side or the retard side. The hydraulic pressure difference is controlled according to the operating conditions, the vane rotor is rotated relative to the shoe housing, and the valve timing is adjusted.
[0003]
During the operation of the engine, torque is transmitted in the order of the shoe housing, the vane rotor, and the camshaft to drive the camshaft to the advanced side. That is, a load is applied to the vane rotor in the advance angle direction. Therefore, when the vane rotor is relatively rotated to the advance side or the retard side, the responsiveness is lower when the vane rotor is relatively rotated to the advance side than when the vane rotor is relatively rotated to the retard side. Also, when the valve timing adjustment device is provided on the exhaust side camshaft, if the exhaust side camshaft is at the retarded position together with the intake side camshaft when the engine is started, the intake valve and the exhaust valve open simultaneously. The lap period becomes unnecessarily long, which is likely to cause poor starting.
[0004]
Therefore, the front end and the rear end of the torsion coil spring are engaged with the shoe housing and the vane rotor, respectively, and the vane rotor is constantly urged in the advance direction with respect to the shoe housing. As a means for engaging the front end of the torsion coil spring, a method is employed in which the front end of the torsion coil spring is an extension extending outward in the radial direction, and is engaged with an engagement pin fixed to the front surface of the shoe housing. (See Patent Document 1). The extension (front end) of the torsion coil spring is housed in a bushing fixed to the front surface of the vane rotor, and is inserted through a spring end insertion groove provided at the front end of the bushing, and is engaged with the engagement pin.
[0005]
[Patent Document 1]
JP-A-2002-295210 (FIGS. 2 and 7)
[0006]
[Problems to be solved by the invention]
When the torsion coil spring is twisted, the length in the axial direction changes, and the position where the extension portion engages with the engagement pin is displaced. For this reason, the spring end insertion groove needs to be formed deep in the axial direction in order to prevent interference with the extension portion, and there has been a problem that the processing of the spring end insertion groove requires time and effort. Further, it is desirable to mold the bushing with a sintered metal from the viewpoints of dimensional accuracy and manufacturing cost. However, in the case of a sintered metal, it is difficult in manufacturing to form the spring end insertion groove with a large depth.
An object of the present invention is to provide a valve timing adjusting device capable of reliably preventing interference between an extension of a torsion coil spring and a spring end insertion groove of a bushing with a simple configuration.
[0007]
[Means for Solving the Problems]
According to the present invention, the front end, which is an extension part that is accommodated in the bushing and extends outward, engages with the engagement pin fixed to the front surface of the shoe housing through the spring end insertion groove provided in the front end of the bushing. And a valve timing adjustment having a torsion coil spring having a rear end engaged with the vane rotor or a member rotating integrally with the vane rotor, and biasing the vane rotor toward the advance side or the retard side with respect to the shoe housing. The device is characterized in that the engagement pin is provided with a spring end holding mechanism for preventing the extension portion from being displaced rearward.
[0008]
In this configuration, the extension of the torsion coil spring is held by the spring end holding mechanism of the engagement pin, and prevents displacement to the rear side. For this reason, even if the torsion coil spring is twisted, the engagement position between the extension and the engagement pin does not change, and interference between the extension and the bushing does not occur. As a result, breakage of the bushing and a change in the spring characteristics of the torsion coil spring can be prevented. As the spring end holding mechanism, a tapered portion provided on the engaging pin according to claim 2 or a peripheral groove provided on the engaging pin according to claim 3 is practical.
[0009]
According to the fourth aspect of the present invention, the bushing accommodating the torsion coil spring is formed of sintered metal together with the spring end insertion groove. Therefore, a bushing with high dimensional accuracy can be manufactured at low cost.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described together with an embodiment shown in the drawings. The valve timing adjusting device 10 includes a shoe housing 1 driven by a crankshaft (drive shaft) via a timing belt (both not shown), and a vane rotor 2 coaxially housed in the shoe housing 1. ing. The vane rotor 2 is driven by the shoe housing 1 and transmits the torque to a camshaft (driven shaft) C. At this time, the vane rotor 2 rotates relatively to the shoe housing 1 and displaces the camshaft C to the advance side or the retard side.
[0011]
The shoe housing 1 includes a housing body 3, an annular sprocket wheel 4, and a plurality of bolts 11 coaxially fastening these components from the front (left side in the figure). In this embodiment, the housing body 3 is made of aluminum and includes an annular front plate portion 31 and a cylindrical body portion 32. A circular central opening 33 is provided at the center of the front plate portion 31, and an axial pin fitting hole 34 is formed in the outer peripheral portion.
[0012]
The body 32 is provided with four chuck grooves 35 on the outer periphery at predetermined intervals in the axial direction, and has four convex portions 36 formed on the inner periphery corresponding to the chuck grooves 35. Each convex portion 36 is connected to the front plate portion 31, and a screw hole 37 penetrates and is opened in the axial direction. Between the convex portions 36 are four concave portions 5 formed radially from the center of rotation. An arc-shaped sliding surface 38 is provided on the center side of each protrusion 36 on the same circumference from the center, and an arc-shaped sliding surface 38 on the outer circumference of each recess 5 is on the same circumference from the center. A moving surface 51 is formed.
[0013]
The sprocket wheel 4 has an annular plate shape, has sprocket teeth 41 formed on the outer circumference, a sliding hole 42 for the camshaft C on the inner circumference, and a bolt hole 43 provided in the middle. The plurality of bolts 11 are inserted into the screw holes 37 through the bolt holes 43, and fasten the housing body 3 and the sprocket wheel 4 integrally. The shoe housing 1 is rotated clockwise in FIG. 2 in synchronization with the crankshaft by a timing chain (not shown) hung on the sprocket wheel 4, and the rotation direction is the advance direction.
[0014]
The vane rotor 2 is provided with four vanes 21 whose center is fastened to the camshaft C by bolts 12 and which defines the four recesses 5 of the shoe housing 1 into an advance chamber 5a and a retard chamber 5b. The vane rotor 2 is provided to be rotatable within a predetermined angle with respect to the shoe housing 1. The advance chamber 5a is a hydraulic chamber for driving the vane 21 to the advance side by hydraulic pressure, and is formed in the concave portion 5 on the anti-rotation direction side of the vane 21. The retard chamber 5b is a hydraulic chamber for driving the vane 21 to the retard side by hydraulic pressure, and is formed in the recess 5 on the rotation direction side of the vane 21.
[0015]
The advance chamber 5a and the retard chamber 5b are hydraulic chambers that are surrounded by the front plate portion 31 and the body portion 32 of the shoe housing 1, the sprocket wheel 4, and the vane rotor 2, and are disposed in the tip groove of the vane 21 and have a sliding surface 51. The liquid tightness in each of the chambers 5a and 5b is maintained by a seal member 22 sliding between the chamber 5 and the seal member 23 disposed between the vane 21 and the slide surface 38.
[0016]
The valve timing adjusting device 10 supplies a hydraulic fluid to the advance chamber 5a and the retard chamber 5b, and supplies a hydraulic pressure difference generating means (not shown) for generating a hydraulic pressure difference between the advance chamber 5a and the retard chamber 5b. Have. The hydraulic pressure difference generating means includes an oil pump driven by a crankshaft, one or a plurality of switching valves for selectively supplying oil pumped by the oil pump to the advance chamber 5a and the retard chamber 5b, and the switching valve. , And a controller for controlling the electromagnetic actuator. The controller generates operating oil pressure in the advance chamber 5a and the retard chamber 5b according to engine operating conditions such as a crank angle, an engine rotation speed, and an accelerator opening detected by various sensors. Due to this hydraulic pressure difference, the vane rotor 2 and the shoe housing 1 rotate relatively.
[0017]
One of the vanes 21 is provided with a stopper pin 24 for fixing the turning position of the vane rotor 2 at a predetermined advanced position (for example, the most advanced position) when the engine is started. The stopper pin 24 is inserted into an insertion hole 25 formed through the vane 21, and a biasing force toward the rear side is applied by a compression coil spring 26. Then, the vane rotor 2 is locked to the shoe housing 1 in a state where the head (rear end) of the stopper pin 24 is fitted into the stopper hole 44 provided in the sprocket wheel 4.
[0018]
An intermediate portion of the stopper pin 24 is formed with a step portion 27 for moving the stopper pin 24 to the front side (direction of disengagement) by hydraulic pressure, and the step portion 27 communicates with the advance chamber 5a. ing. When hydraulic oil of a predetermined pressure or more is supplied to the advance chamber 5a, the stopper pin 24 comes out of the stopper hole 44 against the urging force of the compression coil spring 26 by the operating oil pressure. The rear end face of the stopper pin 24 communicates with the retard chamber 5b. When hydraulic oil of a predetermined pressure or more is supplied to the retard chamber 5b, the operating oil pressure opposes the urging force of the compression coil spring 26. As a result, the stopper pin 24 comes out of the stopper hole 44.
[0019]
As shown in FIGS. 1 and 3, a torsion coil spring (assist spring) 6 for urging the vane rotor 2 to the advance side is provided between the shoe housing 1 and the vane rotor 2. The assist spring 6 has an extension 61 at one end (front end) engaged with the shoe housing 1 or a member rotating integrally with the shoe housing 1, and an extension at the other end (rear end). 62 is engaged with the vane rotor 2 or a member that rotates integrally with the vane rotor.
[0020]
Around the coil portion of the assist spring 6, a cylindrical bushing 7 fitted in a cylindrical recess 60 provided at the center of the vane rotor 2 on the front side is arranged. The bushing 7 prevents the coil portion of the assist spring 6 from interfering with the housing main body 3 or the vane rotor 2, and the housing main body 3 and the vane rotor 2 made of a material having a relatively low hardness (for example, aluminum or soft iron). However, it has an effect of preventing abrasion due to contact with the hard assist spring 6. For this reason, the conventional bushing 7 is made of a material having relatively high hardness (for example, iron, stainless steel, etc.) and is required to have high dimensional accuracy, and is therefore formed by cutting.
[0021]
In this embodiment, the bushing 7 is made of sintered metal and includes a cylindrical portion 71 having an open front side, a side wall 72 provided on the rear side of the cylindrical portion 71, and a boss portion 73 at the center of the side wall 72. At the center of the boss 73, a fastening bolt hole 74 is formed so as to penetrate therethrough. The bushing 7 is required to have hardness and precise dimensional accuracy, and the cutting cost is high, and the required dimensional accuracy cannot be obtained by casting. For this reason, it is advantageous to be made of sintered metal which has excellent productivity and can be manufactured precisely.
[0022]
The front end of the assist spring 6 is an outwardly extending portion 61, which is press-fitted into the pin fitting hole 34 of the front plate portion 31 and is fixed in parallel with the axis of the assist spring 6. Is engaged. An extension portion 61 is inserted into the front end of the cylindrical portion 71 of the bushing 7 with a gap 63 therebetween, and corresponds to a relative rotation angle (about 90 degrees in this embodiment) between the vane rotor 2 and the shoe housing 1. A spring end insertion groove 75 is formed. The other end of the assist spring 6 is a radially inward extension 62, which is fitted in a radial groove 76 provided in a boss 73 of the bushing 7. With the bushing 7 made of sintered metal, it is difficult to form the spring end insertion groove 75 deep in the axial direction.
[0023]
The engaging pin 8 includes a foot portion 81, a cylindrical portion 82, a tapered portion 83 as a spring end holding mechanism, and a disk-shaped head, which are fitted in a pin fitting hole 34 formed in the front plate portion 31 of the shoe housing 1. It comprises a part 84. The extension portion 61 is inserted into the spring end insertion groove 75 and engages with the tapered portion 83 having a smaller diameter toward the front side, and receives a component force toward the front side. For this reason, even if the assist spring 6 is twisted in the contracting direction, the extension portion 61 is prevented from being displaced rearward. As a result, even if the spring end insertion groove 75 has a small axial depth, the interference between the bushing 7 and the spring end insertion groove 75 is reliably prevented.
[0024]
FIG. 4B shows an engagement pin 8 according to another embodiment. In this embodiment, instead of the tapered portion 83, a peripheral groove 85 with which the tip of the extension portion 61 is engaged is formed as a spring end holding mechanism. With this configuration, the same effect as that of the tapered portion 83 can be obtained. The spring end holding mechanism may have a configuration other than the above as long as it has a structure that can prevent the extension portion 61 from being displaced rearward due to the torsional movement of the assist spring 6.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a valve timing adjusting device.
FIG. 2 is a front sectional view of the valve timing adjusting device;
FIG. 3 is a front view of the valve timing adjusting device.
FIG. 4 is a side view of an engagement pin (a), and a side view of an engagement pin of another embodiment (b).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shoe housing 10 Valve timing adjusting device 2 Vane rotor 21 Vane 3 Housing main body 31 Front plate part 32 Body part 33 Central opening 4 Sprocket wheel 5 Depression 5a Advance chamber 5b Delay chamber 6 Assist spring (torsion coil spring)
61 Extension 7 Bushing 75 Spring end insertion groove 8 Engagement pin 83 Taper (Spring end holding mechanism)
85 circumferential groove (spring end holding mechanism)
C Camshaft (driven shaft)

Claims (4)

A valve timing adjusting device that is provided in a driving force transmission system that transmits driving force from a driving shaft of an internal combustion engine to a driven shaft that opens and closes a valve, and causes a phase difference between the rotation of the driving shaft and the rotation of the driven shaft And
A shoe housing that rotates with one of the drive shaft or the driven shaft, has a central opening on the front surface, and has a recess therein.
A bushing that rotates together with the other of the drive shaft and the driven shaft and is coaxially accommodated in the shoe housing, a front end of which is fixed to the front surface, and a bushing that projects forward from the central opening, and the recess is formed as an advance chamber. A vane rotor having a vane partitioned into a retard chamber,
A front end, which is an extension that is accommodated in the bushing and extends outward, engages with an engagement pin fixed to the front surface of the shoe housing by passing through a spring end insertion groove provided in the front end of the bushing. A valve having a torsion coil spring having a rear end engaged with the vane rotor or a member rotating integrally with the vane rotor, and urging the vane rotor toward the advance side or the retard side with respect to the shoe housing. In the timing adjustment device,
A valve timing adjusting device, wherein a spring end holding mechanism for preventing a rearward displacement of the extension portion is provided on the engagement pin. 2. The valve timing adjusting device according to claim 1, wherein the spring end holding mechanism is a tapered portion provided on the engagement pin. 2. The valve timing adjusting device according to claim 1, wherein the spring end holding mechanism is a circumferential groove provided on the engagement pin. 3. The valve timing adjusting device according to any one of claims 1 to 3, wherein the bushing is made of a sintered metal in which the spring end insertion groove is molded at the same time.

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