JPH04164107A - Variable valve timing device - Google Patents

Abstract

PURPOSE:To eliminate backlash of biting and to reduce noises and the sliding resistance by setting the relative position of the first and the second ring gear type sleeve so that the gap between the tooth traces of both sleeves becomes maximum when the clearance between both sleeves is maximum or minimum. CONSTITUTION:The first ring gear type sleeve 5 and the second ring gear type sleeve 6 are set apart and connected to each other by means of a coil spring 7. The space between the two sleeves are set variable from the free length of the coil spring (max.) to zero (min.). The relative position is set so that the tooth traces of the two sleeves coincide when the above-mentioned space of the sleeves lies between the maximum and the minimum value. The backlash is zero when the ring gear type sleeves 5, 6 are at the right or left end. The backlash is generated when the ring gear type sleeves 5, 6 are moving. This arrangement prevents increase of the sliding resistance while the ring gear type sleeves 5, 6 are moving, and improves the operational response.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable valve timing device that changes the valve timing of intake and exhaust valves of an internal combustion engine according to operating conditions.

[Conventional technology]

One of this type of variable valve timing device is shown in Fig. 3 (
As shown in (a) and (b), a timing pulley 31 and a camshaft 32 are coaxially meshed and connected via a ring gear-shaped sleeve 30 in which at least one of the teeth on the inner and outer peripheral surfaces is formed of helical teeth. At the same time, by moving the ring gear-shaped sleeve 30 in the axial direction of the camshaft 32 using a drive mechanism using hydraulic pressure, a coil spring 33, etc., the timing pulley 31 and the camshaft 32 are rotated relative to each other, and the camshaft is rotated. There is a variable valve timing device that advances or slows down the opening and closing timing of intake and exhaust valves according to the operating state of an internal combustion engine.

According to the variable valve timing device, the valve timing of the intake valve can be advanced depending on the operating state of the internal combustion engine, for example, during high-load operation to increase the filling efficiency of the combustible air-fuel mixture and obtain high output. During load operation, by delaying the valve timing of the intake valve,
By reducing the amount of residual burnt gas, it is possible to improve combustion stability and fuel efficiency.

This type of variable valve timing device has a configuration in which a gear (ring gear-shaped sleeve 30) meshes with each tooth of a timing pulley 31 and a camshaft 32, so naturally there is a so-called backlash between these meshes. There is an interlocking gap called ``.

Therefore, due to the existence of this hack crash, while driving,
When the valve spring's neck acts as an alternating load in the rotational direction or counter-rotational direction of the camshaft 32 and causes fluctuations in the rotational torque of the camshaft 32, noise (hitting noise) is generated. .

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 62-3111, the ring gear-shaped sleeve 30 is divided, the intervals between them are increased, and the tooth traces thereof are shifted, thereby eliminating the above-mentioned hasochrane and meshing. Some devices are known that are designed to reduce noise.

In the variable valve timing device described in the above publication, as clearly shown in FIG. 3(b), the ring gear-shaped sleeve 30 has two ring gear-shaped sleeves 40, 41 as gear components, and two ring gear-shaped sleeves 40, 41. A thrust pin 42 that connects two ring gear-shaped sleeves 40.41 in a slidable manner in the axial direction of the camshaft 32, and a thrust pin 42 that is interposed between the two ring gear-shaped sleeves 40.41 and these ring gears It is characterized in that it is constructed with a coil spring 43 which separates the shaped sleeves 40 and 41 and slightly shifts the tooth traces from each other.

[Problem to be solved by the invention]

According to the above publication, the two ring gear-shaped sleeves 4
The spring force of the coil spring 43 interposed between 0 and 41 is large, and the two ring gear-shaped sleeves 40 and 41 are always kept in a spaced apart state, that is, a state in which the bank lash is zero.

However, in variable valve timing devices such as this type that use ring gear-shaped sleeves with helical teeth, the premise of variable phase is that the gears slide in the axial direction while meshing. However, in the case where the bank lash is always zero as described above, the sliding resistance against the axial movement of the ring gear-like sleeve 30 when changing the phase becomes large, and it is difficult to move the ring gear-like sleeve 30. A large driving force is required, and due to the sliding resistance, the ring gear-shaped sleeve 30
There has been a problem in that the moving speed of the motor becomes slow, leading to deterioration of operational responsiveness.

The present invention substantially increases the tooth width of the ring gear-shaped sleeve when the phase is fixed, and prevents the tooth width from becoming small during the phase change, thereby eliminating bank lash when the phase is fixed, and backlash during the phase change. The above-mentioned problem is solved by reducing the sliding resistance when the ring-gear shaped sleeve moves so as to reduce the sliding resistance during movement of the ring gear-shaped sleeve.

[Means for Solving the Problems] According to the present invention, the above problems are solved by the following configuration. That is, in the present invention, the timing pulley and the camshaft are connected by a ring gear-shaped sleeve having at least one helical tooth on the inner and outer circumferential surfaces meshing between the timing pulley and the camshaft. , in a variable valve timing device in which the timing pulley and the camshaft are rotated relative to each other by axial movement of the ring gear-shaped sleeve due to oil pressure switching, and the valve timing is changed; The first ring gear sleeve is divided into a first ring gear sleeve and a second ring gear sleeve, and the first ring gear sleeve and the second ring gear sleeve are divided into a first ring gear sleeve and a second ring gear sleeve.
The second ring gear shaped sleeves are connected by an elastic body that makes the distance between the two ring gear shaped sleeves variable, and the relative positions of the first and second ring gear shaped sleeves are determined by the distance between the first and second ring gear shaped sleeves. is the maximum and minimum, the first and second
The spring force of the elastic body is set such that the displacement of the teeth of the ring gear-shaped sleeve is maximum, and the spring force of the elastic body is set such that the spring force of the elastic body is set such that the displacement of the teeth of the ring gear-shaped sleeve is set to be the maximum, and the spring force of the elastic body is set such that the spring force of the elastic body is set such that the displacement of the teeth of the ring gear-shaped sleeve is set to be the maximum. The distance between the ring gear-shaped sleeve and the second ring gear-shaped sleeve is maximum, and the distance is minimum when it is equal to or greater than a second predetermined value that is larger than the first predetermined value,
The interval is set to be an intermediate value when the oil pressure is greater than or equal to the first predetermined value and less than or equal to the second predetermined value;
is characterized in that it is configured to be movable in the axial direction when the value is less than a predetermined value.

[For production]

Hydraulic pressure acting on the ring gear-shaped sleeve is applied to the first
is less than the predetermined value or greater than the second predetermined value, that is, when the ring gear-shaped sleeve is phase locked at the end of the range in which it can move in the axial direction, the first ring gear-shaped sleeve and the The spacing between the second ring gear sleeves is either maximum or minimum. When the distance between the two ring gear-shaped sleeves is the maximum and the minimum, the deviation of the tooth traces of the two ring gear-shaped sleeves is maximized,
Since the relative positions of both ring gear-shaped sleeves are set, there is no meshing backlash and noise is reduced.

The hydraulic pressure acting on the ring gear-shaped sleeve is
is greater than or equal to the predetermined value and less than or equal to the second predetermined value, that is, during a phase change in which the ring gear sleeve is moving, the distance between the first ring gear sleeve and the second ring gear sleeve is This is the intermediate value between the maximum and minimum values. For example, when the distance gradually decreases from the maximum state, the tooth traces of both ring gear-shaped sleeves change from a misaligned state to a state where the tooth traces gradually become aligned. When the distance is a certain intermediate value between the maximum value and the minimum value, the tooth traces of both ring gear-like sleeves coincide, and as the distance further decreases,
The tooth traces of both ring gear-like sleeves shift again.

Therefore, during the phase change, a backlash occurs in the meshing, and the sliding resistance to the axial movement of the ring gear-like sleeve is reduced.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a block diagram of an embodiment of a variable valve timing device according to the present invention. The upper half shows the state when the oil pressure is OFF, and the lower half shows the state when the oil pressure is ON.

First, the configuration of this embodiment will be explained.

■ is the camshaft. As is well known, a cam is attached to the camshaft of an internal combustion engine, and as the camshaft rotates, intake and exhaust valves attached to the cam move up and down, opening and closing intake and exhaust ports, thereby performing intake and exhaust.

A sleeve 3 is press-fitted onto the peripheral surface of the tip of the camshaft 1 that protrudes outside the engine body from the bearing portion 2 on the side of the timing pulley of the camshaft 1, and is connected to the camshaft 1 by a bolt 4 from the tip of the camshaft 1. It is mounted so that it cannot rotate or move in the axial direction.

Helical teeth are formed on the outer circumferential surface of the sleeve 3 over the entire circumference in the circumferential direction, and on the outer circumferential side, a first tooth is formed from the bearing portion 2 side.
A ring gear-shaped sleeve 5 and a second ring gear-shaped sleeve 6 are arranged in this order, and the teeth formed on the inner circumference of each are meshed with the teeth on the outer circumference of the sleeve 3.

The first ring gear shaped sleeve 5 and the second ring gear shaped sleeve 6 are connected by a coil spring 7 with a distance between them, and the distance between the two is set so that the free length of the coil spring 7 is the maximum and the free length of the coil spring 7 is the minimum. It is said to be variable up to zero.

Moreover, the relative positions of the two teeth are set so that the tooth traces of the two teeth coincide when the distance between the two teeth becomes a certain intermediate value between the maximum and the minimum values.

A timing pulley 8 is provided on the teeth on the outer periphery of the first ring gear shaped sleeve 5 and the second ring gear shaped sleeve 6.
The helical teeth formed on the inner peripheral surface of the sleeves 3 and 3 are engaged with each other, and the driving force transmitted from the crankshaft to the timing pulley 8 is transferred to the ring gear-shaped sleeves 5, 6 and the sleeve 3.
is transmitted to the camshaft 1 via.

In FIG. 1, the left end of the timing pulley 8 is
is attached by bolts 10, and the lid 9 and
The ring gear-shaped sleeves 5 and 6 are placed in a cylindrical space formed by the sleeve 3 and the timing pulley 8.
is stored.

The inner circumferential wall of this space is the outer circumferential surface of the sleeve 3, the outer circumferential wall is the inner circumferential surface of the timing pulley 8, the right wall in the axial direction is the boss of the timing pulley 8, and the left wall in the axial direction is the boss of the timing pulley 8. It is composed of a lid 9.

The space is formed to be longer in the axial direction than the ring gear shaped sleeves 5 and 6.
.

A portion of the space sandwiched between the left end of the second ring gear-shaped sleeve 6 and the lid 9 is configured as a hydraulic chamber 11, and the hydraulic chamber 11 is provided inside the camshaft 1 and is connected to the camshaft. The oil hole 12 that extends from the bearing portion 2 of No. 1 to the tip of the bolt 4 communicates with the oil hole 12 . The oil hole 12 is in communication with an oil hole m13 formed in the bearing part 2 of the camshaft 1 and extending around the bearing part 2 in the circumferential direction, and the groove 13 is in communication with an oil hole 15 in the bearing 14, Further, the oil hole 15 is connected to an oil pump 17 or a drain passage 18 of the engine via a hydraulic pipe 16. The hydraulic piping 16 has a switching valve 19 in its middle that switches the hydraulic pressure between ON and OFF.
is provided, and its operation is controlled by a control circuit 20 that instructs changes in valve timing.

On the other hand, a coil spring 21 is installed between the axial right side wall of the space and the right end of the first ring gear shaped sleeve 5.
6 to the left in the axial direction.

A groove 22 penetrating in the axial direction is provided in the sliding portion of the sleeve 3 with the boss portion of the timing pulley 8, and an oil return passage 24 in the cylinder head 23 and the ring gear-shaped sleeve 5.6 are provided. It communicates with the space in which it is housed.

Further, as shown in the upper half of FIG. 1, when the ring gear-shaped sleeves 5 and 6 are at the left end in the space, the distance between the two ring gear-shaped sleeves 5 and 6 is at the maximum, and As shown in the half, the spring force of the coil spring 7.21 is set so that it is minimum when it is at the right end. That is, when the ring gear sleeves 5 and 6 are at the left end in the space, the spring force of the coil spring 7 between the ring gear sleeves 5 and 6 is applied to the coil on the right side of the first ring gear sleeve 5. When the ring gear sleeves 5 and 6 are at the right end in the space, the spring force of the coil spring 7 between the ring gear sleeves 5 and 6 is greater than the spring force of the spring 21. The spring force of the coil spring 7°21 is set so that it is smaller than the spring force of the coil spring 21 on the right side of the ring gear-shaped sleeve 5 of No.1.

Note that the source pressure of the oil pressure from the oil pump 17 is the coil spring 7 between the ring gear-shaped sleeves 5 and 6;
and is larger than the maximum spring force of the coil spring 21 on the right side of the first ring gear-shaped sleeve 5.

Further, in this embodiment, the ring gear-shaped sleeve 5.6
When the valve timing is at the left end in the space, the valve timing is delayed, and when it is at the right end, the valve timing is advanced.

Next, the effect of the above configuration will be explained.

The valve timing is controlled to be changed when the engine enters a predetermined operating state, but here, an example will be explained in which the valve timing is changed from a delayed valve timing to an advanced valve timing.

Until hydraulic pressure is applied to the hydraulic chamber 11, that is, when the valve timing is fixed to the delayed side, the ring gear-like sleeves 5.6 are inserted into the space in which they are accommodated as seen in FIG. At this time, the spring force of the coil spring 7 between the ring gear-shaped sleeves 5 and 6 is larger than the spring force of the coil spring 21 on the right side of the first ring gear-shaped sleeve 5. As shown in a), the distance between the ring gear-shaped sleeves 5 and 6 is maximum, so that the tooth traces of the two are shifted, and the backlash is zero.

When the operating state of the engine reaches a predetermined state, the control circuit 20
In response to the command, the switching valve 19 is operated, and the hydraulic piping 16 and the oil pump 17 are communicated with each other.

When the hydraulic piping 16 and the oil pump 17 are brought into communication, the hydraulic pressure from the oil pump 17 passes through the hydraulic piping 16, the oil hole 15 of the camshaft bearing 14, 413 of the bearing part 2, and the inside of the camshaft 1. It passes in this order through the oil hole 12 penetrating from the bearing portion 2 to the tip of the bolt 4, and acts on the hydraulic chamber 11 on the left side of the second ring gear-shaped sleeve 6.

At this time, since the spring force of the coil spring 7 between the ring gear-like sleeves 5 and 6 is larger than the spring force of the coil spring 21 on the right side of the first ring gear-like sleeve 5, the ring gear-like sleeve 5, 6 does not decrease, and the coil spring 21 on the right side of the first ring gear shaped sleeve 5 contracts, so that the ring gear shaped sleeve 5
, 6 begin to move to the right in the space.

When the movement begins, the spring force of the coil spring 21 increases. And both coil springs 7.21
When the difference in spring force becomes smaller, coil spring 7
also begins to shrink, and the distance between the two ring gear-shaped sleeves 5.6 becomes smaller. That is, as shown in FIG. 2(b), the distance approaches a certain distance that has been set so that the tooth traces of both the ring gear-shaped sleeves 5 and 6 mentioned above coincide. The hacklash thus occurs and the sliding resistance to the axial movement of the ring gear sleeve 5.6 is reduced.

Furthermore, when the ring gear-shaped sleeves 5 and 6 move, the spring force of the coil spring 7.21 is reversed, and the spring force of the coil spring 7 becomes relatively smaller, so that both ring gear-shaped sleeves 5 The interval between .6 is further reduced. When the distance between the two ring gear-shaped sleeves 5, 6 is further reduced than the interval at which the tooth traces of both the ring gear-shaped sleeves 5, 6 coincide, the tooth traces gradually rub together again. When the ring gear sleeve 5.6 moves to the right end of the space, the distance between the ring gear sleeves 5.6 becomes minimum, as shown in FIG. 2(C). The tooth trace of No. 6 is shifted and the hacklash becomes zero.

Further, at this time, since the ring gear-shaped sleeves 5 and 6 have moved to the right end of the space, the timing pulley 8 and the camshaft 1 are rotating relative to each other, and the valve timing has been switched to the advance side.

When hydraulic pressure is applied to the hydraulic chamber 11, oil gradually leaks to the right from the gap between the teeth of the ring gear-shaped sleeves 5, 6 and the timing pulley 8 or the sleeve 3. The oil that has entered the space on the right side of the first ring gear-shaped sleeve 5 passes through the groove 22 provided at the right end of the sleeve 3 and flows out to the oil return passage 24 in the cylinder head 23. Returned to the inside of the engine.

When returning the valve timing from the advanced side to the delayed side, the control circuit 20 cuts off communication between the hydraulic piping 16 and the oil pump 17 with respect to the switching valve 19, and connects the hydraulic piping 16 to the drain passage 18. Issue a command to communicate with.

Since the hydraulic pipe 16 is connected to the drain passage 18, no hydraulic pressure acts on the hydraulic chamber 11, and the ring gear-shaped sleeves 5, 6 are moved to the left side by the coil spring 21 on the right side of the first ring gear-shaped sleeve 5. be pushed back. At this time, the first ring gear-shaped sleeve 5
The relative position between and the second ring gear shaped sleeve 6 is as follows:
The behavior is completely opposite to the case where the valve timing is changed from the delayed side to the advanced side as described above. In other words, the 18
, the effect can be obtained.

When said ring gear sleeve 5.6 is returned to the left side,
The oil in the hydraulic chamber 11 is passed through an oil hole 12 that passes from the tip of the port 4 through the inside of the camshaft 1 to the bearing portion 2;
It passes through the groove 13 of the bearing portion 2, the oil hole 15 of the bearing 14, and the hydraulic pipe 16 in this order, passes through the switching valve 19, passes through the drain passage 18, and returns to the oil pan.

As explained above, in this embodiment, when the ring gear-shaped sleeves 5 and 6 are at the left and right ends of the space in which they are housed, that is, the valve timing is fixed to either advance or retard. Sometimes, the backlash is zero, meshing noise is prevented, and when the ring gear-like sleeve 5.6 is moving, that is, when changing the valve timing, the bank lash occurs, so that the ring gear An increase in sliding resistance during movement of the shaped sleeves 5 and 6 is prevented, and operational responsiveness is improved.

(Effects of the Invention) According to the present invention, when the ring gear-shaped sleeve is located at the axial end of the space in which it is housed, which is the area in which valve timing is actually used, there is no hacklash and the mesh is not engaged. On the other hand, when changing the valve timing, during the movement of the ring gear sleeve, backlash is prevented from occurring and increasing sliding resistance, improving operational response and lowering the operating oil pressure level. It can be suppressed.

[Brief explanation of the drawing]

FIG. 1 shows a configuration diagram of an embodiment of a variable valve timing device according to the present invention. The upper half shows the state when the oil pressure is OFF, and the lower half shows the state when the oil pressure is ON. FIGS. 2(a), (b), and (c) show the relationship between the change in the interval between the first ring gear-shaped sleeve and the second ring gear-shaped sleeve and the change in the tooth traces of both of the variable valve timing device of this embodiment. A schematic diagram is shown. (a) shows the position of both the tooth traces when the distance between the two is the maximum, (b) shows the position of the both tooth traces when the distance between the two is an intermediate value, (C) shows the positions of the two tooth traces when the distance between the two is the minimum. FIGS. 3(a') and 3(b) show configuration diagrams of a conventional variable valve timing device. (a> is an overall configuration diagram of a conventional variable valve timing device,
(b) is a block diagram of a gear structure. Explanation of symbols 1--11-1 Camshaft 5--1 First ring gear-shaped sleeve 6--
-1 Second ring gear shaped sleeve 7 -1 Coil spring 8 -1 Timing pulley 11 - Hydraulic chamber 20 - Control device 21 − Coil spring applicant Toyota Motor Corporation

Claims (1)

[Claims] A ring gear-shaped sleeve in which at least one of the teeth on the inner and outer peripheral surfaces is formed with helical teeth is meshed between the timing pulley and the camshaft, thereby connecting the timing pulley and the camshaft. In the variable valve timing device, the timing pulley and the camshaft are rotated relative to each other by axial movement of the ring gear-shaped sleeve due to oil pressure switching, and the valve timing is changed. The ring gear shaped sleeve is divided into a first ring gear shaped sleeve and a second ring gear shaped sleeve, and the interval between the first and second ring gear shaped sleeves is variable. The relative positions of the first and second ring gear-shaped sleeves are connected by an elastic body, and the relative positions of the first and second ring gear-shaped sleeves are
When the distance between the first and second ring gear shaped sleeves is maximum and minimum, the displacement of the tooth traces of the first and second ring gear shaped sleeves is set to be maximum, and the elastic body is The spring force is such that when the hydraulic pressure acting on the ring gear sleeve is less than or equal to a first predetermined value, the distance between the first ring gear sleeve and the second ring gear sleeve becomes maximum, and the first ring gear sleeve The interval is set to be the minimum when it is equal to or greater than a second predetermined value that is larger than the predetermined value, and the interval is set to be an intermediate value when it is equal to or greater than the first predetermined value and less than or equal to the second predetermined value, and A variable valve timing device characterized in that the ring gear-shaped sleeve is configured to be movable in the axial direction when the oil pressure is greater than or equal to the first predetermined value and less than or equal to the second predetermined value.