JPH0656086B2 - Valve timing adjusting device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing adjusting device that variably controls opening / closing operation timings of intake and exhaust valves of an internal combustion engine according to operating conditions.

2. Description of the Related Art As a valve timing adjusting device of this type, a cylindrical gear having at least one of the teeth provided on the inner and outer circumferences between the timing pulley and the camshaft is a helical gear, and an outer tooth provided on the outer circumference. To the inner teeth provided on the inner circumference of the timing pulley, and the inner teeth provided on the inner circumference to the outer teeth provided on the outer circumference of the camshaft, respectively, so that the rotation of the timing pulley can be transmitted to the camshaft. By moving the gear in the axial direction of the cam shaft by a gear drive mechanism using a hydraulic pump, a coil spring, etc., the timing pulley and the cam shaft are relatively rotated, and the opening / closing timing of the intake / exhaust valve by the cam shaft is changed by the internal combustion engine. It is known that the engine is adapted to progress according to the operating condition of the engine (for example, US Pat. No. 4.231.330). issue).

The above-mentioned conventional valve timing adjusting device is a simple operation of moving the gear in the axial direction of the camshaft by hydraulic pressure or the like, and depending on the operating condition of the internal combustion engine, for example, advances the timing of closing the intake valve during high load operation. High efficiency can be obtained by increasing the filling efficiency of the combustible mixture, and at the time of low load operation, the timing of closing the intake valve is delayed to reduce the amount of residual burnt gas, thereby improving combustion stability and fuel economy. Can be improved.

However, in this valve timing adjusting device, since the gear is configured to mesh with the teeth of the timing pulley and the camshaft, it is natural that there is a meshing gap called a so-called "backlash" between the meshes. Therefore, due to the existence of this backlash, when the spring force of the valve spring acts as an alternating load in the rotational direction or the anti-rotational direction of the camshaft during operation to cause fluctuations in the rotational torque of the camshaft, the noise of meshing is generated. (Striking sound) may occur, or the timing of opening / closing the intake / exhaust valves may become unstable, which is extremely bad.

For this reason, the present applicant previously filed Japanese Patent Application No. 60-12.
No. 3371 proposes a valve timing adjusting device as shown in FIG. This is a plurality of gear components 3c, 3d in which the gear 3 is slightly staggered from each other.
Are connected via an elastic member 3e, and the apparent tooth thicknesses of the outer teeth 3a and the inner teeth 3b are adjusted by moving the gear components 3c and 3d in the axial direction and the rotation direction, The gear 3 meshes with the inner tooth 1a of the timing pulley 1 and the outer tooth 2a of the camshaft 2 with zero backlash. In addition, 5 is a timing belt.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a conventional valve timing adjusting device, a gear configured such that the spring force of the elastic member 3e acts in a direction in which the plurality of gear components 3c and 3d draw each other. In the case of No. 3, when the gear 3 is meshed between the timing pulley 1 and the camshaft 2, there are the following problems.

That is, since the gear components 3c and 3d of the gear 3 are generally formed by cutting and dividing a long gear and have the same outer teeth 3a and inner teeth 3b, the gear components 3c and 3d before meshing are Since the elastic members 3e are in contact with each other by the spring force, the apparent tooth thicknesses of the outer teeth 3a and the inner teeth 3b of the gear 3 at this time are larger than their original tooth thicknesses. . To engage with the inner teeth 1a of the timing pulley 1 of the gear 3, the gear structure 3
By slightly twisting c and 3d, the outer teeth 3a
The apparent tooth thickness of the inner tooth 1a of the timing pulley 1
Must be smaller than the width of the tooth space. Then, the apparent tooth thickness of the inner tooth 3b of the other gear 3 is further increased, and the outer tooth 2a of the camshaft 2 is increased.
When meshed with the outer teeth 2a, as shown in FIG. 5, the outer teeth 2a come into contact with the inner teeth 3b of the gear structure 3c and stop.
From this state, the outer tooth 2a meshes with the inner tooth 3b, so that the gear component 3c moves axially with respect to the gear component 3d to reduce the apparent tooth thickness of the inner tooth 3b. It would be good if the gear structure 3
c is in contact with the bottom portion 1b of the timing pulley 1 and cannot move in the axial direction. Therefore, the camshaft 2 is unavoidably pressed in the axial direction to force the inner teeth 3b.
I was meshing with. In this way, although the meshing is achieved, the outer teeth 2a of the camshaft 2 and the inner teeth 3b of the gear structure 3c may be damaged or damaged. In order to achieve such a forced meshing, the apparent tooth thickness of the inner tooth 3b of the gear 3 is appropriate while the inner tooth 1a of the timing pulley 1 and the outer tooth 3a of the gear 3 are meshed. Must be small,
Special accuracy is required to create each tooth. Furthermore, in order to make the apparent tooth thickness of the inner teeth 3b of the gear 3 appropriately small in the above-described state, the amount by which the tooth configuration of the gear components 3c and 3d is shifted (specifically, each gear component is different). It is necessary to reduce the cutting width for obtaining the bodies 3c and 3d), and the amount by which the meshing of the gears 3 can be adjusted in terms of backlash is small, so that at the end of long-term use. There is concern about the occurrence of backlash.

The present invention was made by paying attention to such conventional problems, and the teeth formed on the outer periphery of the camshaft are
(EN) A valve timing adjusting device for an internal combustion engine, which is easily meshed with a plurality of gear components to prevent damage to the tooth surface, has excellent durability, and can be manufactured at low cost. It is what

Therefore, according to the present invention, of the two gear components forming the gear, the gear component on the side where the camshaft is first inserted is moved in the axial direction. It is provided with a locking portion with which a restricting jig is engaged.

When engaging a gear and a camshaft, one gear component provided with a locking portion is supported by a jig and its axial movement is restricted, and the other gear component is two gear components. It is possible to move in the axial direction while receiving the spring force of the elastic member that connects the gears, so that the engagement can be easily achieved.

Embodiment Hereinafter, a valve timing adjusting device for an internal combustion engine according to the present invention will be described based on an embodiment shown in FIGS.

FIG. 1 is a sectional view showing a meshed state of a gear 3 used in the valve timing adjusting device of the present invention. In the figure, 1
Is a timing pulley, and inner teeth 1a are formed on the inner circumference thereof. Reference numeral 2a denotes outer teeth formed on the outer circumference of the camshaft 2 and, in this embodiment, the sleeve 2b integrally rotatably connected to the camshaft 2. Three
Is a gear, and the gear 3 is generally formed by cutting and dividing a long gear in the longitudinal direction, two gear components 3c and 3d having the same outer teeth 3a and inner teeth 3b, and one gear. The elastic member 3e and the connecting pin 3 which are fitted to the structural body 3d to connect the other gear structural body 3c of the gear structural body 3d.
and a jig 6 for restricting the axial movement of the gear component 3d is engaged with the end of the gear component 3d on the side where the outer teeth 2a of the camshaft 2 are first inserted. A locking portion 3g is formed. The jig 6 is the camshaft 2
The outer tooth 2a is used when meshing with the inner tooth 3b of the gear 3, and a claw 6a that engages with the locking portion 3g is formed on the base portion 6b.

The procedure for engaging the gear 3 between the inner tooth 1a of the timing pulley 1 and the outer tooth 2a of the camshaft 2 will be described below. First, the gear components 3c and 3d are slightly screwed to align the outer teeth 3a with each other, and are meshed with the inner teeth 1a of the timing pulley 1. Next, the base portion 6b of the jig 6 is placed on the step portion 1c formed at one end of the timing pulley 1, and the claw 6a is engaged with the locking portion 3g of the gear structure 3d. Then, as shown in FIG. 1, the gear 3 is supported by the jig 6 with a clearance d from the bottom portion 1b of the timing pulley 1, and the gear structure 3c is movable in the axial direction (downward in the drawing). Becomes Then, in this state, the outer teeth 2a of the camshaft 2 are inserted into the inner teeth 3b of the gear assembly 3d. Then, the outer teeth 2a come into contact with the inner teeth 3b of the gear structure 3c at the positions shown in the schematic view of FIG. 2 (a). At this time, the apparent tooth thickness of the inner tooth 3b is larger than the width of the tooth groove of the outer tooth 2a,
Since the apparent width of the tooth groove is smaller than the tooth thickness of the outer tooth 2a, the inner tooth 3b of the gear structure 3c and the outer tooth 2a cannot be meshed with each other as it is. Outer teeth 2a
Is pressed downward with a force larger than the spring force of the elastic member 3e in the axial direction, the gear structure 3c follows the tooth line of the inner tooth 1a of the timing pulley 1 which is already meshed, as shown in FIG. ) Move as shown. Then, the width of the apparent tooth groove of the inner tooth 3b increases, and when the width becomes larger than the tooth thickness of the outer tooth 2a, the outer tooth 2
a also meshes with the inner teeth 3b of the gear structure 3c. In this manner, the gear 3 is assembled between the inner tooth 1a of the timing pulley 1 and the outer tooth 2a of the camshaft 2 while receiving the spring force of the elastic member 3e with zero meshing of each mesh. is there. After this assembly is completed, the jig 6 is removed.

FIG. 3 shows a state in which the gear 3 is mounted between the timing pulley 1 and the camshaft 2 so as to be slidable in the axial direction of the camshaft 2 as described above. The gear 3 is driven by a gear drive mechanism 4. The gear drive mechanism 4 includes a hydraulic pump 4a that supplies hydraulic pressure to one end of the gear 3 and a return spring 4b that is housed between the other end of the gear 3 and the spring receiver 7, and operates under high load. Occasionally, hydraulic pressure is supplied from the hydraulic pump 4a to one end side of the gear 3 through a hydraulic passage 4d provided in the camshaft 2, and the gear moves to the right in FIG. 3 while compressing the return spring 4b. Then, the camshaft 2 rotates in one direction with respect to the timing pulley 1 to advance the timing of closing the intake valve to improve the charging efficiency. Further, during low load operation, when the hydraulic pressure supply from the hydraulic pump 4a to one end side of the gear 3 is stopped, the gear 3 moves leftward in FIG. 3 by the spring force of the return spring 4b to close the intake valve. By delaying this, the amount of residual burned gas is reduced, and combustion stability and fuel efficiency are improved.

As described above, according to the present invention, the gear that connects the timing pulley and the camshaft is composed of two gear components, and the gear component on the side where the camshaft is first inserted has the axial direction thereof. Since it has a locking portion with which a jig for restricting the movement of the gear is engaged, when the gear meshed with the timing pulley is meshed with the cam shaft, a force larger than the spring force of the elastic member pulling the two gear components together is used. Only by pressing the camshaft, the gear and the camshaft can be meshed with each other, so that the meshing work is extremely easy and the following effects can be obtained.

(1) Since it is not necessary to press the camshaft forcibly to mesh with the gear, the teeth of the gear and the camshaft are not damaged or damaged during the meshing.

(2) Since it is not necessary to reduce the backlash that meshes with the timing pulley and the camshaft gears, it is not necessary to create each tooth with particular accuracy. That is, the manufacturing cost can be reduced.

(3) Since the cutting width when cutting and splitting the gear can be increased, the adjustment allowance for the apparent tooth thickness of the outer and inner teeth of the gear is increased, and the wear caused by the meshing of each tooth is reduced. The durability is improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state in which a gear used in the valve timing adjusting device of the present invention is meshed between a timing pulley and a cam shaft, and FIGS. 2 (a) and 2 (b) are inner teeth of the gear and a cam shaft. Schematic showing engagement with outer teeth, third
FIG. 4 is a cross-sectional view showing an embodiment of a valve timing adjusting device of the present invention, FIG. 4 is a cross-sectional view of a conventional valve timing adjusting device, and FIG. 5 is a view showing engagement between inner teeth of a conventional gear and outer teeth of a camshaft. It is a schematic diagram showing. 1 ... Timing pulley, 1a ... Inner tooth, 2 ... Camshaft, 2a ... Outer tooth, 3 ... Gear, 3a.
Outer teeth, 3b ... Inner teeth, 3c, 3d ... Gear structure, 3e ... Elastic member, 3g ... Locking part, 6 ... Jig.

Claims (1)

[Claims] 1. A plurality of gear structures in which at least one of the teeth formed on the inner and outer circumferences is a helical tooth, and the tooth lines are slightly displaced from each other, and are connected via elastic members. A gear consisting of a body is attached by meshing it between a timing pulley and a cam shaft, and the rotation of the timing pulley can be transmitted to the cam shaft, and by moving the gear in the axial direction of the cam shaft with a gear drive mechanism, In a valve timing adjusting device for an internal combustion engine, wherein a cam shaft is relatively rotated with respect to the timing pulley, and opening / closing operation timings of intake and exhaust valves by the cam shaft can be changed, the gear includes two gear components. The gear structure on the side where the camshaft is first inserted is equipped with a locking part with which a jig that restricts its axial movement engages. The valve timing control apparatus for an internal combustion engine.