JPH07190174A - Backlash reducer - Google Patents

Abstract

PURPOSE:To obtain appropriate backlash reducing action corresponding to the rotating speed of a rotary shaft with simple constitution. CONSTITUTION:A backlash reducer is provided with a fixed gear such as a driven gear 7 fixed to a rotary shaft formed of a camshaft 2, a movable gear 8 supported in the relatively displaceable state to the fixed gear, an engaging gear such as a driving gear 6 engaged with the movable gear 8 and the fixed gear. The tooth face of the movable gear 8 is brought into pressure contact with the tooth face positioned on the back face side in the rotating direction of the engaging gear, and a driving means 13 is provided to change this pressure contact force in correspondence with the rotating speed of the rotary shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlash reducing device for reducing backlash generated between gears meshing with each other.

[0002]

2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Utility Model Laid-Open No. 4-18755, a friction gear having a different number of teeth is installed on one side of two gears meshing with each other, and the friction gear is formed by a disc spring. It is known to press the gear side. The backlash generated between the gears is reduced by the frictional force generated according to the pressing force.

[0003]

When the conventional device having the above-mentioned structure is applied to the torque transmitting portion between the camshafts of the engine, as shown in FIG. 8, the torque required to reduce the backlash is reduced. While the backlash reducing force C corresponding to the frictional force generated by the biasing force of the disc spring is set to be substantially constant while the engine speed changes according to the engine speed, the engine speed is constant (for example, 4000).
If it exceeds (rpm), the frictional force becomes insufficient, and there is a problem that the torque A required to reduce the backlash cannot be obtained.

Further, when the engine speed is lower than the above-mentioned constant value, the frictional force corresponding to the biasing force of the disc spring becomes larger than the torque A required for reducing the backlash, which causes The transmission efficiency of the driving force is reduced according to the friction loss, and it is difficult to adjust the pressing force of the disc spring to set the biasing force to an appropriate value, which makes the assembly work complicated. There was a problem.

The present invention has been made to solve the above-mentioned problems, and it is possible to obtain an appropriate backlash reducing force corresponding to the number of rotations of a rotary shaft with a simple structure and to facilitate the assembling work. It is an object of the present invention to provide a backlash reduction device that can be used for the above.

[0006]

The invention according to claim 1 is
The movable gear includes a fixed gear fixed to the rotating shaft, a movable gear supported so as to be relatively displaceable with respect to the fixed gear, and an engagement gear engaged with the movable gear and the fixed gear, respectively. The tooth surface of (1) is brought into pressure contact with the tooth surface located on the back side in the rotation direction of the engaging gear, and a drive means for changing the pressure contact force in accordance with the rotation speed of the rotary shaft is provided.

According to a second aspect of the present invention, a fixed gear, which is a helical gear attached to the rotary shaft, a movable gear, which is a helical gear, is provided so as to be displaceable relative to the fixed gear, and the movable gear and An engaging gear that is engaged with each of the fixed gears is provided, and by applying an urging force corresponding to the rotation speed of the rotating shaft in the axial direction of the movable gear, the meshing phase of the movable gear with respect to the engaging gear is changed. Drive means for driving the movable gear is provided so as to be different from the phase of the fixed gear.

According to a third aspect of the present invention, there is provided a backlash reducing device for reducing backlash of a gear provided in an engine, wherein a drive means for applying a driving force to the movable gear according to the engine speed is provided. It is a thing.

[0009]

According to the first aspect of the present invention, the unnecessary pressure contact force is adjusted because the pressure contact force of the movable gear pressed against the tooth surface of the fixed gear is adjusted as the rotation speed of the rotary shaft changes. Therefore, backlash that occurs between the fixed gear and the engaging gear is effectively reduced.

According to the second aspect of the present invention, the movable gear, which is a helical gear, moves along the rotation axis in accordance with the urging force applied from the driving means, so that the movable gear and the helical gear are separated from each other. The meshing phase with the fixed gear changes according to the inclination angle of the tooth surface. As a result, the tooth surface of the movable gear is brought into pressure contact with the tooth surface located on the rear side in the rotation direction of the engagement gear, and the backlash between the fixed gear and the engagement gear is reduced.

Further, since the pressure contact force of the movable gear pressed against the tooth surface of the fixed gear is adjusted as the rotation speed of the rotary shaft changes, the back force that changes according to the rotation speed of the rotary shaft is adjusted. A backlash reducing force corresponding to the torque in the rush direction can be obtained.

According to the third aspect of the present invention, since the pressure contact force of the movable gear pressed against the tooth surface of the fixed gear provided in the engine is adjusted as the engine speed changes. Backlash that occurs between the fixed gear and the engaging gear is effectively reduced without applying unnecessary pressure contact force.

[0013]

FIG. 1 shows a cylinder head portion of an engine equipped with a backlash reducing device according to an embodiment of the present invention. In this engine, a pair of cam shafts 2 and 3 are arranged in parallel at the upper end of a cylinder head 1. One of the pair of cam shafts 2 and 3 is for an intake valve, and the other cam shaft 3 is for an exhaust valve.

One of the pair of cam shafts 2 and 3 is driven by an output shaft (not shown) of the engine via a timing belt 4 as a transmission means, and one of the cam shafts (drive side cam shaft) is driven. Power is transmitted to the other cam shaft (driven side cam shaft) from the gear). In this embodiment, of the pair of camshafts 2 and 3, the camshaft 3 for the exhaust valve is the drive-side camshaft.
The timing belt 4 is wound around the cam pulley 5 at the end of the engine and the pulley at the end of the engine output shaft.

The pair of cam shafts 2 and 3 are respectively rotated at a plurality of positions by bearing portions where journal portions 2a and 3a are formed on the cylinder head 1 and corresponding cam caps (not shown). It is supported freely. A thrust plate (not shown) for preventing the cam shafts 2 and 3 from moving in the axial direction.
Is provided.

The cam shafts 2 and 3 are provided with cams 2b and 3b corresponding to the valves of the cylinders. Further, the camshaft 3 for the exhaust valve, which serves as the drive-side camshaft, is provided with a cam pulley 5 at its end, and a drive gear 6 is provided adjacent to this, so that the intake-side camshaft for the driven-side camshaft is provided. A driven gear 7 that meshes with the drive gear 6 is provided on the valve camshaft 2. These gears 6 and 7 are helical gears. The driven camshaft 2 is provided with a movable gear 8 which is adjacent to the driven gear 7 and meshes with the driving gear 6.

The driven gear 7 is, as shown in FIG.
It is fixed by a mounting bolt 10 to a flange portion 9 provided at the end of the camshaft 2. The movable gear 8 is composed of a helical gear having a tooth profile of the same standard as that of the driven gear 7, and a shaft portion 11 protruding from one end face of the movable gear 8 has an engaging hole 12 formed in the cam shaft 2 and It is configured to be fitted into the mounting hole of the driven gear 7.
Spline teeth are formed on the outer periphery of the base end of the shaft 11.

A spline groove that meshes with a spline tooth of the shaft portion 11 is formed in a mounting hole of the driven gear 7, and the movable gear 8 is engaged with the spline groove by engaging the spline groove with each other. And its shaft portion 11 is slidably supported along the spline groove of the driven gear 7, and the rotational driving force transmitted from the driving gear 6 to the movable gear 8 is driven via the spline coupling portion. 7 and the camshaft 2 so that they rotate together.

Further, the backlash reducing device is
The oil discharged from the oil pump driven by the output shaft of the engine is introduced into the engagement hole 1 of the camshaft 2
By supplying the movable gear 8 to the inside of the camshaft 2, the driving means 13 is provided which is a hydraulic pressure supply means for urging the shaft portion 11 in the end direction of the camshaft 2, that is, in the direction of separating from the driven gear 7. ing. Then, the drive means 1
As shown in FIG. 3, the movable gear 8 slides in the direction away from the driven gear 7 in accordance with the hydraulic pressure supplied from the driving gear 7, and the back gear between the driving gear 6 and the driven gear 7 is moved. It is configured to reduce rush.

That is, as shown in FIG. 2, at the mounting position where the driven gear 7 and the movable gear 8 are in close contact with each other, the tooth flanks inclined at a predetermined angle with respect to the axial direction of both gears 7, 8 are formed. As shown in FIG. 3, the movable gear 8 is slidably displaced in the direction away from the driven gear 7 in accordance with the hydraulic pressure of the driving means 13 from the consecutively installed positions of the driven gears. Between the tooth flank of 7 and the tooth flank of the movable gear 8, a phase shift t corresponding to the inclination angle of the tooth flank occurs. Then, according to the phase shift t, the respective gears 6 to 8 are rotated in a state where the tooth surface of the movable gear 8 is pressed against the tooth surface located on the rear side in the rotational direction of the drive gear 6. Therefore, the effect of reducing backlash according to the pressure contact force can be obtained.

Further, the hydraulic pressure of the drive means 13 increases in proportion to the engine speed as shown in FIG.
By setting the diameter of the shaft portion 11 driven by the hydraulic pressure to an appropriate value, as shown in FIG. 5, a negative torque A generated in the camshaft 2 corresponding to the engine speed, that is, input to the camshaft 2. A torque B larger than the torque acting on the driven gear 7 in the backlash direction is obtained in almost all regions of the engine rotation speed according to the driven operation, whereby the backlash is effectively reduced. Become.

In this way, the tooth flank of the movable gear 8 provided adjacent to the driven gear 7 is brought into pressure contact with the tooth flank located on the rear side in the rotation direction of the driving gear 6, whereby the driving gear 6 is driven. Backlash generated when the force is transmitted to the driven gear (fixed gear) 7 is absorbed, and the pressure contact force is changed according to the rotational speed of the camshaft 2, that is, the rotational speed of the engine. Therefore, even when the engine speed increases and a large negative torque A acts, the pressure contact force increases,
Backlash can be effectively reduced.

When the engine speed is low,
Since the urging force of the drive means 13 for pressing the tooth surface of the movable gear 8 to the tooth surface located on the rear side in the rotation direction of the drive gear 6 is also small, a substantially constant pressing force C as in the conventional device is applied. An unnecessary biasing force does not act as in the case of applying the force, and the friction loss in the area indicated by the diagonal line α can be reduced as compared with the conventional device. Moreover, when the movable gear 8 is assembled, the urging force of the driving means 13 is not applied, so that the movable gear 8 can be easily assembled at an appropriate position, and the assembling work can be facilitated. it can.

In the above embodiment, the movable gear 8 is moved from the mounting position where the movable gear 8 is in close contact with the driven gear 7 as shown in FIG. 2 to the position separated from the driven gear 7 as shown in FIG. 8 is configured to be slidably displaced so that the meshing phases of the two gears 7 and 8 are different from each other. However, as shown in FIG. , 8 may be attached in a state where the meshing phases of the gears 8, 8 are matched.

Then, the hydraulic pressure is supplied from the driving means 13 into the hydraulic chamber 14 disposed on the side of the movable gear 8, and the movable gear 8 is slid and displaced so that the movable gear 8 is brought into close contact with the driven gear. A phase shift t may be generated between 7 and 8. In this embodiment, the driven gear 7 is fixed to the flange portion 9 of the cam shaft 2 by the knock pin 15, and the movable gear 8 is slid and displaced along the positioning pin 16 provided upright on the driven gear 7. Is configured to.

Further, instead of the above structure in which the movable gear 8 is provided on the intake valve cam shaft 2 to which the driven gear 7 is fixed, the exhaust valve cam shaft 3 side to which the driving gear 6 is fixed is replaced. The movable gear 8 may be provided.

Further, instead of the drive gear 6, driven gear 7 and movable gear 8 which are helical gears, a drive gear 6, a driven gear 7 and movable gear 8 which are spur gears may be provided. In this case, a spiral spline groove or a key groove is formed on the rotary shaft to which the movable gear 8 is attached, whereby the movable gear 8 is slidably displaced along the rotary shaft while being rotationally displaced. The meshing phase of the drive gear 7 and the movable gear 8 can be made different.

Further, in the above-described embodiment, the example in which the movable gear 8 having the same standard as the fixed gear composed of the driven gear 7 is provided has been described. May be brought into pressure contact with the driven gear 7 by the hydraulic pressure supplied from the drive means 13, and the pressure contact force may be changed according to the rotation speed of the rotary shaft. Further, in the above-described embodiment, the example in which the backlash of the driven gear 7 and the driving gear 6 attached to the camshafts 2 and 3 provided in the engine is reduced has been described. The configuration of the present invention can be applied to the gear provided in the.

[0029]

As described above, in the invention according to claim 1, the tooth surface of the movable gear, which is provided so as to be relatively displaceable with respect to the fixed gear fixed to the rotary shaft, is arranged in the rotational direction of the fixed gear. Since the pressure contact force is applied to the tooth surface located on the back side and the pressure contact force is changed according to the rotation speed of the rotary shaft, the rotation speed of the rotary shaft increases and a large torque acts in the backlash direction. Even in such a case, by increasing the pressure contact force by the drive means, it is possible to effectively reduce the backlash and suppress the generation of noise.

When the rotation speed of the rotary shaft is small,
Since the urging force of the drive means for pressing the tooth surface of the movable gear to the tooth surface located on the rear side in the rotation direction of the fixed gear is small, the friction loss due to the unnecessary urging force is reduced. be able to. Moreover, since the assembling work of the movable gear can be performed in a state where the urging force of the driving means is not applied, there is an advantage that the movable gear can be easily assembled at an appropriate position.

According to the second aspect of the invention, the meshing phase of the movable gear with respect to the engagement gear is achieved by moving the movable gear, which is a helical gear, along the rotation axis according to the biasing force applied from the driving means. And the phase of the fixed gear composed of a helical gear are made different from each other, the tooth surface of the movable gear is pressed against the tooth surface located on the rear side in the rotation direction of the engaging gear in accordance with the amount of deviation of the meshing phase. There is an advantage in that the force can be changed easily and appropriately, and thereby the backlash between the fixed gear and the engaging gear can be effectively reduced.

According to the third aspect of the invention, the tooth surface of the movable gear is located on the rear side in the rotation direction of the fixed gear by applying hydraulic pressure from the drive means to the movable gear according to the number of revolutions of the engine. Since the driving means for contacting the tooth surface of the engine and changing the pressure contact force according to the rotation speed of the rotary shaft is provided, the backlash of the gear provided in the engine can be effectively reduced with a simple structure. Can be suppressed.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a backlash reduction device according to the present invention.

FIG. 2 is a cross-sectional plan view showing a main part of the backlash reduction device.

FIG. 3 is a view corresponding to FIG. 2 showing a state in which an urging force of a drive means is applied.

FIG. 4 is a graph showing a correspondence relationship between engine speed and oil pressure.

FIG. 5 is a graph showing the relationship between engine speed and torque.

FIG. 6 is a half sectional plan view showing another embodiment of the backlash reduction device.

FIG. 7 is a view corresponding to FIG. 6 showing a state in which the urging force of the drive means is applied.

FIG. 8 is a graph showing the relationship between engine speed and torque in a conventional device.

[Explanation of symbols]

 2 camshaft (rotating shaft) 6 driving gear (engaging gear) 7 driven gear (fixed gear) 8 movable gear 13 driving means

Claims (3)

[Claims] 1. A fixed gear fixed to a rotating shaft, and a movable gear supported so as to be relatively displaceable with respect to the fixed gear,
The movable gear and the engagement gear that are respectively engaged with the fixed gear are provided, and the tooth surface of the movable gear is brought into pressure contact with the tooth surface located on the rear side in the rotation direction of the engaging gear,
A backlash reduction device characterized in that a drive means is provided for changing the pressure contact force in accordance with the rotation speed of the rotary shaft. 2. A fixed gear composed of a helical gear attached to a rotary shaft, a movable gear composed of a helical gear provided so as to be relatively displaceable with respect to the fixed gear, and the movable gear and the fixed gear, respectively. If the engagement phase of the movable gear with respect to the engagement gear is different from the phase of the fixed gear by applying an urging force corresponding to the rotation speed of the rotation shaft in the axial direction of the movable gear, A backlash reduction device, characterized in that a driving means for driving the movable gear is provided so that the backlash can be reduced. 3. A backlash reducing device for reducing backlash of a gear provided in an engine, characterized by further comprising drive means for applying a driving force to a movable gear in accordance with an engine speed. Claim 1 or Claim 2
The backlash reduction device according to any one of 1.