JPH068708U - Valve timing control device for internal combustion engine - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] In a valve timing control device for an internal combustion engine, it is possible to reduce the thickness of the tubular main body of the timing pulley, improve the flexibility of the molding method and material selection, and reduce the cost. And weight reduction. [Structure] Phase conversion means 5 for converting a relative rotational phase between a timing pulley 1 and a cam shaft 2, and a pulley body 6
And a front cover 9 fixed to the front end edge 6c by swaging. The phase converting means 5 includes a piston 14 that is movable in the axial direction, a plurality of sliders 17 to 20 provided at a front end portion of the piston 14, and a camshaft via the sliders 17 to 20 as the piston 14 moves. And an arm 13 for rotating the 2 forward and backward.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a valve timing control device that variably controls the opening / closing timing of an intake valve or an exhaust valve of an internal combustion engine according to operating conditions.

[0002]

[Prior art]

 Various valve timing control devices of this type have been conventionally provided, and one of them is disclosed, for example, in Japanese Utility Model Laid-Open No. 2-46007.

Briefly described, a timing pulley in which a rotational force is transmitted from a crankshaft of an engine via a timing belt, and a cam for operating an intake valve or an exhaust valve by the rotational force transmitted from the timing pulley. And a sleeve axially bolted to one end of the camshaft. In the timing pulley, a gear part around which a timing belt is wound is attached by bolts to the outer periphery of the rear end of a cylindrical pulley body, and a front cover is fixed to the front end by caulking.

Further, between the inner teeth formed on the inner circumference of the pulley body and the outer teeth formed on the outer circumference of the sleeve, at least one of the inner and outer teeth is formed into a helical tooth shape. The cylindrical gears are meshed with each other. This tubular gear moves in the camshaft axial direction by the hydraulic pressure of the hydraulic circuit and the spring force of the compression coil spring according to the engine operating state, thereby converting the relative rotational phase between the timing pulley and the camshaft. The intake / exhaust valve opening / closing timing is variably controlled.

[0005]

[Problems to be solved by the device]

 However, in the above-described conventional valve timing control device, the timing pulley and the cam shaft are configured to convert the relative rotational phase by using the inner and outer teeth of the helical gear of the cylindrical gear. These inner and outer teeth are required to be machined with high precision in order to ensure good meshing accuracy between the inner teeth of the timing pulley and the outer teeth of the sleeve.

On the other hand, a front cover is fixed to the front end portion of the timing pulley by swaging the front end edge of the pulley body. Therefore, the pulley main body may be deformed during such caulking, and the accuracy of meshing between the inner teeth and the outer teeth of the tubular gear may be reduced. For this reason, it may be possible to set the thickness of the pulley body to a large value to prevent easy deformation during crimping, but if the wall thickness is set to a large value, the molding size of the pulley body and the freedom of material selection are restricted. Incurring higher manufacturing and material costs and increased weight.

[0007]

[Means for Solving the Problems]

 The present invention has been devised in view of the conventional situation described above, and includes a rotating body that is rotationally driven by an engine, and a camshaft having a cam that operates an intake / exhaust valve by the rotational force transmitted from the rotating body. A phase conversion means interposed between the rotating body and the camshaft for converting a relative rotational phase between the rotating body and the camshaft; and a front cover fixed by caulking to the front end edge of the cylindrical body of the rotating body. In the valve timing control device, the phase conversion means includes a piston slidably provided in an axial direction of the camshaft, a plurality of movable members provided at an end of the piston, and one end of the camshaft. And an arm that is fixed to the arm and that rotates forward and backward through a movable member as the piston slides.

[0008]

[Action]

 According to the present invention having the above-described structure, the phase shifting means is replaced with the conventional inner and outer teeth of the cylindrical gear, which mesh with the inner and outer teeth, and the piston or the piston slides in the axial direction of the camshaft. Since it is composed of an arm that rotates by movement, it is not necessary to increase the sliding accuracy of the piston between the tubular body and the camshaft. Therefore, even if the tubular body or the like is slightly deformed when the tubular body is caulked, it does not affect the slidability of the piston. Therefore, the tubular body can be made as thin as possible, and the flexibility of the molding method and material selection can be improved.

[0009]

【Example】

 1 to 3 show a first embodiment of the present invention applied to the intake valve side of a DOHC type valve operating mechanism of a gasoline engine, in which a rotational force is transmitted from a crankshaft of the engine via a timing belt. A cylindrical timing pulley 1 that is a body, a cam shaft 2 that is arranged coaxially with the timing pulley 1 and that has a cam that opens the intake valve by the rotational force transmitted from the timing pulley 1, and the cam shaft. A sleeve 4 is fixed to one end 2a of the shaft 2 in the axial direction by a bolt 3, and a phase conversion means 5 interposed between the sleeve 4 and the timing pulley 1.

In the timing pulley 1, a gear portion 7 around which a timing belt is wound is fixed by bolts 8 to a flange portion 6a provided in the substantially central outer periphery of a cylindrical pulley body 6, while an opening at a front end portion is provided. Is closed by the front cover 9. The entire main body 6 is formed to have a relatively small thickness, and the inner peripheral surface 6b is formed to have a step diameter. The rear end of the pulley body 6 is rotatably supported by the one end 2a of the camshaft 2 via a holding member 10 having a substantially annular shape. The front cover 9 is composed of an annular portion 9a on the outer peripheral side and a disc-shaped lid portion 9c screwed together with the seal ring 100 in the central hole 9b of the annular portion 9a with male and female screws. The outer periphery of the annular portion 9a is caulked and fixed by the front end edge 6c of the pulley body 6. Further, in the holding member 10, the flange portion 10a on the front end side is caulked and fixed by the rear end edge 6d of the pulley body 6. Incidentally, seal rings 11 and 12 are interposed between the outer peripheral surfaces of the annular portion 9a and the flange portion 10a and the inner peripheral surface 6b of the pulley body 6.

The phase conversion means 5 includes an arm 13 that is fastened to the tip 4 a of the sleeve 4 together with the front cover 9 by the bolt 3 and the axial direction of the camshaft 2 between the sleeve 4 and the timing pulley 1. It is composed of an annular piston 14 that is slidably in contact with the piston 14 and is movable back and forth, and four sliders 17 to 20 provided at the front end of the piston 14 via a coil spring 15 and pins 16 ... There is.

As shown in FIG. 2, the arm 13 is formed by extending side surfaces 21a, 21b, 22a, 22b of extension portions 21 and 22 extending in a diametrical direction in a slanting direction in mutually opposite directions. On the other hand, each of the sliders 17 to 20 has a substantially rectangular piece shape, and one side surface 17a to 20a abutting each side surface 21a to 22b is formed in an inclined shape at the same angle as each side surface 21a to 22b. The other side surfaces 17b to 20b are disposed in contact with the concave inner peripheral surfaces of the projections 23 and 24 provided on the inner peripheral surface of the cylindrical body 1a.

The piston 4 is moved forward and backward by a drive mechanism including a compression spring 25 and a hydraulic circuit 26. The hydraulic circuit 26 is formed inside the camshaft 2, the bolt 3, etc., and has a main passage 26a whose upstream end communicates with an oil pump 28 via an electromagnetic switching valve 27, a head portion of the bolt 3, and a lid portion 9c. And a communication passage 26b which is formed between the main passage 26a and the hydraulic chamber 29 on the front end side of the piston 4 and which is formed between the main passage 26a and the inner end surface of the piston. The electromagnetic switching valve 27 is configured to perform switching operation according to a control signal output from the control unit 30 which detects an engine operating state. Reference numeral 31 in the drawing is a pressure adjusting valve for adjusting the discharge pressure of the oil pump 28 to a constant value.

The operation of this embodiment will be described below. That is, when the engine load is low, the electromagnetic switching valve 27 is controlled by the control signal from the control unit 30, and the supply of hydraulic oil to the hydraulic chamber 29 is cut off. Therefore, the piston 14 moves forward by the spring force of the compression spring 25, and the side surfaces 17a, 19a of the sliders 17, 19 press the opposing end surfaces 21a, 22a of the arm 13 while timing the arm 13. The pulley 1 is rotated in the direction opposite to the rotating direction. As a result, the camshaft 2 relatively rotates in one direction with respect to the timing pulley 1 to control the closing timing of the intake valve to the delayed side.

On the other hand, when shifting to the high load range, the hydraulic oil pressure-fed from the oil pump 28 via the electromagnetic switching valve 27 is supplied to the hydraulic chamber 29 through the main passage 26a and the communication passage 26b. The piston 14 moves backward as the pressure in the hydraulic chamber 29 rises. Accordingly, the side surfaces 18a and 20a of the different sliders 18 and 20 press the opposite facing end surfaces 21b and 22b of the arm 13 to rotate the arm 13 in the rotational direction of the timing pulley 1. As a result, the cam shaft 2 relatively rotates in the other direction with respect to the timing pulley 1 to control the closing timing of the intake valve to the advanced side.

As described above, according to the present embodiment, the relative rotational phase of the timing pulley 1 and the camshaft 2 is converted by merely linear movement of the piston 14 in the axial direction. It is not necessary to set the moving accuracy to a high level, that is, the dimensional accuracy of the inner and outer diameters of the piston 14, the inner diameter of the pulley body 6 and the outer diameter of the sleeve 4 are better than the meshing accuracy of the conventional cylindrical gear. Does not have to be too high. Therefore, when the front and rear edges 6c and 6d of the pulley body 6 are caulked, even if the pulley body 6 or the like is slightly deformed, the slidability of the piston 14 is not affected. As a result, the thickness of the pulley body 6 can be set as thin as possible. Therefore, the pulley main body 6 can be formed by the powder metal sintering method which is low in processing cost, and the weight can be reduced.

Further, in this embodiment, since the rear inner peripheral side of the piston 14 is cut out to shorten the length of the entire piston 14, the weight can be reduced in this respect as well. Since the compression spring 25 is formed in a substantially conical shape and the tip side is elastically held by the shaft end of the pin 16 facing the pin hole of the piston 14, the pressing action of the side compression spring 25 on the piston 14 is stabilized. Can be achieved.

The order of assembling the components in this embodiment will be briefly described. First, the sliders 17 to 20 are fixed to the front end of the piston 14 by the coil spring 15 and the pin 16, and the arm 13 is fixed. Subassemblies to the sleeve 4 and mounts in the pulley body 6, respectively. After that, the annular portion 9b is caulked and fixed to the front end portion of the pulley body 6, the compression spring 25 is attached, and the holding member 10 is caulked and fixed to the rear end portion of the pulley body 6. After that, the arm 13 and the sleeve 4 are fixed to the one end portion 2a of the camshaft 2 by the bolt 3, and finally the lid 9c having the seal ring 100 mounted thereon and the compression spring 32 is mounted between the arm 13 and the lid. The portion 9c is screwed and attached to the central hole 9b of the annular portion 9a.

As described above, since the respective constituent parts can be sequentially and efficiently carried out from the front and rear of the pulley body 6, the assembling work efficiency can be improved. Particularly, since the front and rear end edges 6c and 6d of the pulley body 6 are swaged to assemble the respective components, the assembly work efficiency is further improved as compared with the case of bolt tightening.

FIG. 4 shows a second embodiment of the present invention, in which the projection at the rear end of the piston 14 is eliminated and the whole is formed in a flat shape. That is, the piston 14 has a function of suppressing the tilt of the sliders 17 to 20 when the sliders 17 to 20 are slid by setting the length in the two axial directions of the camshaft to a long value. The sliders 17 to 20 themselves are provided. That is, the sliding contact area of the inner peripheral surface 6b with which the sliders 17 to 20 of the pulley body 6 are slidably contacted is made large so that the entire outer peripheral surface of each slider 17 to 20 slidably contacts with the inner peripheral surface 6b. . Therefore, the axial length of the piston 14 can be shortened as much as possible. As a result, the piston 14 can be molded by a so-called fine blanking press that performs a precision punching process in one stroke, and therefore, the efficiency of the molding process can be improved.

The rest of the configuration is the same as that of the first embodiment, and the same effect as the first embodiment can be obtained.

FIG. 5 shows a third embodiment of the present invention. In this embodiment, a torque transmission pin 33 is interposed between the sleeve 4 and the arm 13 and the torque transmission pin 33 is inserted. The pin hole 13a on the side of the arm 13 formed is not a through hole but a so-called bag hole having a bottom surface.

Therefore, the torque transmission pin 33 improves the rotational torque transmission from the arm 13 to the camshaft 2 through the sleeve 4 and prevents the arm 13 and the sleeve 4 from rattling. You can Further, by making the pin hole 13a a blind hole, the side of the pin hole 13a can be fitted to the sleeve 4 when it is assembled to the sleeve 4, so that an error in assembling the front and back of the arm 13 can be prevented.

The present invention can be applied to timing sprockets as well as timing pulleys.

[0025]

[Effect of device]

 As is clear from the above description, according to the present invention, the phase conversion means is constituted by a piston or the like instead of the conventional cylindrical gear, and therefore, the inner circumference of the piston and the cylindrical main body on which the piston slides It is not necessary to make the dimensional accuracy of the surface and the outer peripheral surface of the camshaft higher than before. Therefore, even if the tubular body is slightly deformed when the front edge is caulked, it does not affect the slidability of the piston. As a result, the thickness of the tubular body can be reduced as much as possible, so that the degree of freedom in the molding method and material selection of the tubular body is improved, and manufacturing and material costs can be reduced and the weight can be reduced.

[Brief description of drawings]

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

FIG. 2 is a view on arrow A in FIG.

3 is a sectional view taken along line BB of FIG.

FIG. 4 is a sectional view showing a second embodiment of the present invention.

FIG. 5 is a sectional view showing a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Timing pulley (rotating body) 2 ... Cam shaft 2a ... One end part 4 ... Sleeve 5 ... Phase conversion means 6 ... Pulley main body (cylindrical main body) 6c ... Front edge 9 ... Front cover 13 ... Arm 14 ... Piston 17-20 ... Slider (movable member)

Claims (1)

[Scope of utility model registration request] 1. A rotary body rotationally driven by an engine, a cam shaft having a cam for operating an intake / exhaust valve by a rotational force transmitted from the rotary body, and an interposition between the rotary body and the cam shaft. In the valve timing control device including the phase conversion means for converting the relative rotational phase of the both, and the front cover crimped and fixed to the front end edge of the cylindrical body of the rotating body, the phase conversion means includes A piston provided slidably in the axial direction of the camshaft, a plurality of movable members provided at the end of the piston, and fixed to one end of the camshaft and movable as the piston slides. A valve timing control device for an internal combustion engine, comprising: an arm that rotates forward and backward through a member.