JPH0577843B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a valve timing adjustment device that performs variable control of the opening and closing timing of intake and exhaust valves of an internal combustion engine.

Conventional technology The fourth valve timing adjustment device of this type
As shown in the figure, a cylindrical gear 3, at least one of which is a helical tooth, is provided between the timing pulley 1 and the camshaft 2 on the inner and outer peripheries.
The outer teeth 3a provided on the outer periphery are meshed with the inner teeth 1a provided on the inner periphery of the timing pulley 1, and the inner teeth 3b provided on the inner periphery are meshed with the outer teeth 2a provided on the outer periphery of the camshaft 2. The rotation of the timing pulley 1 can be transmitted to the camshaft 2, and the gear 3 is connected to the hydraulic pump 4a.
By moving the camshaft 2 in the axial direction with a gear drive mechanism 4 using a coil spring 4b or the like, the timing pulley 1 and the camshaft 2 are rotated relative to each other, and the opening/closing timing of the intake and exhaust valves by the camshaft 2 is controlled. It is known that the internal combustion engine is advanced or retarded depending on the operating conditions of the engine (for example, US Pat. No. 4,231,330). Note that 5 is a timing belt.

Problems to be Solved by the Invention The conventional valve timing adjustment device described above has a simple operation of moving the gear 3 in the axial direction of the camshaft 2 using hydraulic pressure or the like, and adjusts the timing according to the operating condition of the internal combustion engine, for example, during high-load operation. In some cases, it is possible to delay the timing of closing the intake valve to increase the efficiency of the combustible mixture and obtain high output, and during low-load operation, by advancing the timing of closing the intake valve (earlier), residual burnt gas can be reduced. By reducing the amount of gas, it is possible to improve combustion stability and fuel efficiency.

However, since this valve timing investigation device has a configuration in which the gear 3 meshes with each tooth of the timing pulley 1 and the camshaft shaft 2, a meshing gap called a so-called bump crush naturally exists between these meshes. . Therefore,
Due to the existence of this bounce, during operation, the spring force of the valve spring acts as an alternating load in the rotational direction or counter-rotation direction of the camshaft 2, causing fluctuations in the rotational torque of the camshaft 2, resulting in meshing noise. In some cases, the timing of opening and closing the intake and exhaust valves became unstable.

Means for Solving the Problems Therefore, in the present invention, the gear that connects the timing pulley and the camshaft is made up of a plurality of gear structures having outer teeth and inner teeth, and these plural gear structures are connected to the camshaft. It is composed of a thrust pin that is slidably connected in the axial direction, and a coil spring that is interposed between the gear components to separate the gear components and slightly shift the tooth traces of each other.

Action When the coil spring is compressed, the gear components are brought close to each other, and the tooth traces of these gear components are aligned, the gear is attached to the timing pulley and camshaft, and the coil spring is released from the compression. Due to the spring force of the coil spring, the gear components are separated, and the mutual tooth traces are slightly shifted to fill the gap. Therefore, the gear is attached to the timing pulley and camshaft with no backlash, and the valve timing adjustment device functions while preventing meshing noise caused by the presence of backlash.

Embodiment Next, an embodiment of the present invention will be described based on the drawings.

FIG. 1 is an exploded perspective view of a gear 3, which is the gist of the present invention. The gear 3 is generally formed by cutting and dividing a long gear, and has the same outer teeth 3a and inner teeth 3b.In this embodiment, it has two gear components 3c and 3d, and one gear component. A thrust pin 3e is attached to the camshaft 2, and the thrust pin 3e is attached to the camshaft 2 so as to be slidable in the axial direction of the camshaft 2. , 3d and a coil spring 3f whose tooth traces are slightly shifted from each other. 3g is a gear structure 3c for attaching a coil spring 3f,
Spring receiving hole provided on one side of 3d, 3h
is a retaining ring attached to the tip of the thrust pin 3e.

The coil spring 3f is attached to the thrust pin 3
e, the gear structures 3c and 3d are connected to each other so as to be movable in the rotational direction and the axial direction by the spring force of the coil spring 3f itself. Here, the mutual movement of the gear structures 3c and 3d in the rotational direction and axial direction increases the apparent tooth thickness of the teeth formed on the inner and outer peripheries of these, and the inner teeth 1a of the timing pulley 1 and the camshaft shaft increase. This makes it possible to assemble the gear 3 to each of the two outer teeth 2a with zero backlash.

In other words, since at least one of the teeth (both in this example) formed on the inner and outer circumferences is a helical tooth, the gear structure 3 cut and divided as described above
By connecting c and 3d with a dimension wider than the cutting width, the mutual tooth traces are slightly shifted, and the apparent tooth thickness generated in the connected gear components 3c and 3d increases. I will do it.

Therefore, the gears 3 connected and configured in this manner are brought together to have substantially the same dimension as the cutting width, and meshed with the inner teeth 1a of the timing pulley 1 and the outer teeth 2a of the camshaft 2, respectively. As a result, each of the gear components 3c and 3d is operated by an axial spring force generated by the coil spring 3f itself.
The tooth grooves of the inner teeth 1a of the timing pulley 1 and the outer teeth 2a of the camshaft 2 that are meshed are moved in a direction to make the meshing backlash zero, and the backlash of the gear 3 for the timing pulley 1 and the camshaft 2 is made zero. The relative is fulfilled.
At this time, the spring force provided by the coil spring 3f has not been exhausted, and the assembled state with zero bounce is maintained thereafter. Incidentally, since at least one of the teeth formed on the inner and outer peripheries of the gear 3 is a helical tooth, when each of the gear components 3c and 3d is driven by the spring force of the coil splinter 3f and the backlash is zero, Since these teeth mesh with the teeth of the timing pulley 1 and the camshaft 2 with a wedge effect, the camshaft 2 is rotationally driven without placing an excessive burden on the coil spring 3f in transmitting torque.

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. This gear drive mechanism 4 includes a hydraulic pump 4a that supplies hydraulic pressure to one end of the gear 3 via a pressure receiving piston 4c, and a hydraulic pump 4a that supplies hydraulic pressure to one end of the gear 3.
It consists of a return spring 4b attached to the other side, and during high load operation, the hydraulic pump 4
Hydraulic pressure is supplied from a to one end side of the gear 3 through a hydraulic passage 4d provided in the camshaft 2, and when the gear 3 moves to the right in FIG. 3 while compressing the return spring 4b due to the oil pressure, the timing pulley 1
On the other hand, the camshaft 2 rotates in one direction to advance the timing of closing the intake valve, thereby increasing the filling efficiency. Also, during low load operation, the hydraulic pump 4a
When the supply of hydraulic pressure to one end of the gear 3 is stopped, the gear 3 moves to the left in FIG. 3 by the spring force of the return spring 4b, and the camshaft 2 rotates in the other direction relative to the timing pulley 1. By delaying the timing of intake valve closing (reducing valve overlap), the amount of residual burnt gas is reduced, improving combustion stability and fuel efficiency.

Although the embodiment shown in the drawings uses a hydraulic pump for the gear drive mechanism 4, a step motor or the like may be used instead of the hydraulic pump to drive the gear 3.
It may be configured to move in the axial direction of the camshaft 2.

Effects of the Invention As explained above, the present invention provides a gear 3 that connects the timing pulley 1 and the camshaft 2.
Since it is composed of a plurality of gear components 3c and 3d connected by a thrust pin 3e and having a coil spring 3f interposed therebetween, the gear components 3c and 3d are slightly shifted from each other.
By adjusting the apparent tooth thickness of the teeth formed on the inner and outer peripheries of the gears c and 3d, this gear 3 is set to have zero backlash with respect to each of the inner teeth 1a of the timing pulley 1 and the outer teeth 2a of the camshaft 2. Can be assembled. Therefore, it is possible to prevent the occurrence of meshing noise due to the presence of backlash, and it is also possible to stabilize the timing of opening and closing the intake and exhaust valves. Further, a gear 3 and a timing pulley 1 that meshes with the gear 3
The inner teeth 1a of the camshaft 2 and the outer teeth 2a of the camshaft 2
Even if the finishing accuracy of the valve is made low, there will be no unevenness in the mesh, and the function of the valve timing adjustment device will not be degraded.
Manufacturing becomes easy and manufacturing costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of the gear component of a gear used in the valve timing adjustment device of the present invention, Fig. 2 is a partially fragmented sectional view of the assembled state, and Fig. 3
The figure is a sectional view of a valve timing adjustment device showing an embodiment of the present invention, and FIG. 4 is a sectional view of a conventional valve timing adjustment device. 1...Timing pulley, 1a...Inner tooth,
2...Camshaft, 2a...Outer tooth, 3...
Gear, 3a...outer tooth, 3b...inner tooth, 3
c, 3d...Gear structure, 3e...Thrust pin, 3f...Coil spring.

Claims (1)

[Claims] 1. A cylindrical gear 3 in which at least one of the teeth provided on the inner and outer peripheries is a helical tooth is provided between the timing pulley 1 and the camshaft shaft 2, and the outer teeth 3a provided on the outer periphery of this gear 3 are connected to the timing pulley 1. The inner teeth 1a provided on the inner periphery of the camshaft 2 are meshed with the outer teeth 2a provided on the outer periphery of the camshaft 2, so that the rotation of the timing pulley 1 can be transmitted to the camshaft 2. At the same time, by moving the gear 3 in the axial direction of the camshaft 2 using the gear drive mechanism 4, the camshaft 2 is rotated relative to the timing pulley 1, and the opening/closing timing of the intake and exhaust valves by the camshaft 2 is adjusted. In the valve timing adjustment device for an internal combustion engine, the gear 3
A plurality of gear structures 3c and 3d each having an outer tooth 3a and an inner tooth 3b, a thrust pin 3e that connects these gear structures 3c and 3d so as to be slidable in the axial direction of the camshaft 2; It is interposed between gear components 3c and 3d,
A valve timing adjustment device for an internal combustion engine characterized by comprising a coil spring 3f which separates these gear components 3c and 3d and slightly shifts their tooth traces.