JP2876819B2 - Backlash adjustment method for gear-driven balancer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlash adjusting method for a gear driven balancer in a four-cylinder engine.

[0002]

2. Description of the Related Art In a four-cylinder engine, when the pistons of the first and fourth cylinders are located at the top dead center, the pistons of the second and third cylinders are located at the bottom dead center. Due to the unbalance of the inertial force due to the inertial mass, an upward unbalance force remains.
Similar upward unbalance force remains even when the piston of the cylinder No. 2 is at the top dead center position, so that two vertical vibrations occur per one rotation of the crankshaft.

[0003] In order to take the vibration due to the unbalance of the inertial force due to the reciprocating inertial mass of the piston, connecting rod and the like peculiar to the four cylinders, an unbalanced mass is provided which balances the unbalance of the inertial force due to the reciprocating inertial mass of the piston and connecting rod. A balance shaft is provided and the crankshaft 1
In some cases, a balancer that rotates two times per rotation is provided. However, if only one balance shaft is provided, the vertical vibration due to the secondary inertial force generated by the unbalance of the inertial force due to the reciprocating inertial mass of the piston, the connecting rod, etc., is eliminated, but the right and left due to the unbalance mass of the balance shaft itself. Since directional vibration is generated, in order to eliminate this, two balance shafts are provided, and they are arranged side by side and are rotated in reverse to cancel the imbalance in the left-right direction.

[0004] When two balance shafts are arranged below the crankshaft and the balance shaft is rotated in conjunction with the crankshaft, the rotation transmission method is as follows.
Conventionally, there are a chain drive type, a belt drive type, and a gear drive type. For example, Japanese Patent Laying-Open No. 58-160647 discloses a gear drive system. The gear drive type has less mechanical loss compared to the chain drive type and the belt drive type, and the balancer can be added relatively easily without adding large fluctuations to the cylinder block structure of the existing balancerless engine. Despite the benefits, there are the following problems that need to be addressed.

[0005]

That is, the gear-driven balancer has a relatively loud noise (hereinafter, referred to as rattle).
(Called a rattle). The loudness of the rattle is particularly large when the distance between the shaft centers between the crank gear and the balancer gear is large and the substantial backlash between the gears is large. If the backlash is made too small in order to reduce the rattle noise, the backlash between the crank gear and the balancer gear becomes zero, causing gear breakage.

[0006] Adjusting the distance between the axes of the crank gear and the balancer gear to each engine so as to minimize rattle without causing gear breakage requires a large amount of work and work time. It was considered inappropriate to introduce it into the engine assembly line, and even though it could be adjusted, the balance shaft had an unbalanced mass and the balance shaft centered in a circular motion within the metal clearance. In the past, it was thought that the rattle noise could not be effectively suppressed because the distance between the shaft centers of the crank gear and the balancer gear fluctuated. In consideration of this, set the distance between gears to a large value, and do not adjust the distance between the crank gear and balancer gear. The attachment to the lock has been performed.
Therefore, noise control was sacrificed.

An object of the present invention is to provide a method of adjusting backlash between a crank gear and a balancer gear for reducing rattle in a gear-driven balancer. However, the inter-gear backlash adjustment method must be a method that can be executed in a relatively short time for each engine without causing gear damage due to zero backlash.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a gear for rotating a balance shaft twice per rotation of a crankshaft by meshing a crank gear mounted on a crankshaft and a balancer gear mounted on a balance shaft. A method for adjusting a backlash of a driven balancer is achieved by providing the following steps. That is, for one revolution of the crankshaft, two points of the crankshaft's most deceleration point and two points of the mass nearest point where the unbalance mass of the balance shaft comes closest to the crank gear are obtained.
Measuring the backlash at the points, and determining the shim for adjusting the distance between the axes of the crank gear and the balancer gear so that the backlash at the point showing the minimum backlash value among the four points becomes the target value. Process.

[0009]

When the generation of rattle noise is analyzed, it is found that the rattle noise occurs twice per rotation of the crankshaft, and occurs at the crankshaft maximum deceleration point (the point where deceleration changes to acceleration). From this, the point of time to manage the backlash on the balancer noise is 2 per crankshaft rotation.
It turned out to be the crankshaft's maximum deceleration point that appeared. Also, if the backlash between gears is less than zero, gear breakage may occur, and backlash is minimized at the point where the unbalance mass of the balance shaft comes closest to the crankshaft, so this point is also managed in terms of gear reliability. There is a need to. In the present invention, gear noise and gear breakage are effectively prevented by setting backlash measurement points as rattle noise generation points and danger points in gear reliability, and directly managing them.

Normally, considering the variation width (for example, 66 microns) of four measurement points on the processing accuracy,
Since a target value must be set for the sum of the variation between the four points (66 microns) and the adjustment variation of each point (for example, ± 24 microns), (for example, (2 × 2
4 + 66 + α microns) / 2, about 60 microns), and the target value cannot be set to a small value in consideration of gear breakage. For this reason, there is a problem that the backlash cannot be reduced because the variation in the backlash of the gear is small even if the variation in the backlash of the gear is small in terms of machining accuracy.
In the present invention, since the target value is determined for the minimum backlash, the target value can be set small (for example, 30 microns). Therefore, the backlash setting of the product can be reduced. For example, if the variation of the four points is 20 microns, and if the target value is 60 microns, there is no problem if it is set to 50-70 microns.
Set to 0-50 microns. As described above, in the present invention, by setting the backlash to be small, the rattle of the balancer is suppressed to the minimum.

The backlash of the point showing the minimum backlash value among the four measurement points is set to a target value (for example, 3
0 microns), so even if there is a variation in backlash adjustment error (for example, ± 24 microns),
The occurrence of a state where the backlash is zero or less can be prevented (for example, 30 microns−24 microns = 6 microns,
There is still room for 6 microns) and no gear breakage occurs.

[0012]

1 to 5 show a preferred embodiment of the present invention. As shown in FIGS. 3 and 4, in a four-cylinder engine, a first balance shaft housing 6 and a second balance shaft housing 8 are fixed to a cylinder block 2 via shims 4. Cylinder block 2
, The crankshaft 10 is rotatably supported, and the first
Between the balance shaft housing 6 and the second balance shaft housing 8 are two balance shafts 1.
2, 14 are rotatably supported.

The two balance shafts 12, 14 are symmetrically disposed below the crankshaft 10. The crankshaft 10 extends in the longitudinal direction of the engine, and the two balance shafts 12, 14 also extend in the longitudinal direction of the engine. The two balance shafts 12 and 14 are disposed near the center of the crankshaft 10 in the longitudinal direction. Each of the two balance shafts 12 and 14 has an unbalance mass 1
6 and 18, the sum of these unbalance masses 16 and 18 balances the unbalance of the inertial force due to the reciprocating inertial mass of the piston, the connecting rod and the like in the vertical direction of the engine.

One of the two balance shafts 12, 14 is gear-driven from the crankshaft 10, and the other balance shaft 14 is gear-driven from the one balance shaft 12. The two balance shafts 12, 14 are rotated in opposite directions, thereby balancing the unbalance masses 16, 18 in the left-right direction.

The crankshaft 10 includes a crank gear 2
The balance shaft 12 is connected to a balancer gear 22, and the balance shaft 14 is connected to a balancer gear 24. Then, the crank gear 20 and the balancer gear 22 mesh with each other, and the balancer gear 22 and the balancer gear 24 mesh with each other. The meshing portion between the crank gear 20 and the balancer gear 22 is offset in the engine longitudinal direction from the meshing portion between the balancer gear 22 and the balancer gear 24. The balancer gears 22, 24 are housed in the balance shaft housings 6, 8 so that the rotation of the balancer gears 22, 24 does not stir the oil in the engine oil pan 26.

The shaft of the balancer gear 22 and the crank gear 2
The distance between the zero axis and the inter-gear backlash varies depending on the thickness of the shim 4. The selection of the shim thickness is set so as to reduce the noise of the balancer. However, if the value is set too small, the state where the backlash is zero does not occur due to variations in gear processing accuracy and backlash adjustment. In order to enable such backlash adjustment, a mechanism of generating noise of the balancer gear was examined.

FIG. 2 shows the result of analyzing the rattle noise generated by the balancer when the engine is idling. As shown in FIG. 2, the rattle is 2 per rotation of the crankshaft 10.
This occurs at a position where the crankshaft 10 rotates 30 ° and 210 ° from the piston top dead center position of the first cylinder. In terms of crank rotation fluctuation, the positions at 30 ° and 210 ° are the crank's maximum deceleration points, and correspond to the points where the transition from deceleration to acceleration occurs. That is, when the teeth of the crank gear 20 hit the front side in the rotation direction of the teeth of the balancer gear 22 during deceleration, the teeth of the crank gear 20 hit the rear side in the rotation direction of the teeth of the balancer gear 22 instead of during acceleration. Since there is a backlash gap between the gears, it is considered that a collision occurs and a sound is generated. At the positions of 30 ° and 210 ° of the crankshaft 10, the unbalance mass 16 of the balance shaft 12 is far from the crankshaft 10 as shown in FIG. It is located far from the shaft 10 by the amount of the metal clearance, and the backlash between gears is large. For this reason, the collision sound increases. From the above rattle noise analysis, two points (30 °,
210 °) is considered to be a desirable reference point in reducing noise and managing backlash.

In adjusting the backlash, it is necessary to manage the backlash so that the backlash does not become zero or less from the viewpoint of preventing gear damage. Since the balance shaft 12 has the unbalance mass 16, the balance shaft 12
Makes a circular motion by the metal clearance of the bearing. Thus, the inter-gear backlash varies depending on the rotational position of the unbalance mass 16. Then, when the unbalance mass 16 of the balance shaft 12 comes to the position closest to the crankshaft 10 (100 ° and 280 ° in the crank angle after the piston top dead center) is the time when the backlash is smallest, Shaft 10
Appears twice per rotation of. This is also a desirable reference point for managing backlash.

The amount of backlash should be as small as possible to reduce gear noise. However, the backlash cannot be reduced to less than zero due to gear reliability. In consideration of these two conditions, the backlash is measured at the four reference points shown in FIG. 1, and the backlash at the point showing the minimum value of the four backlash values is adjusted to the target value. I do.

FIG. 5 is a flowchart showing an example of steps according to the backlash adjusting method. This adjustment method has two stages. The first stage is a stage for determining the target shim, and the second stage is a stage for checking whether the backlash amount is within a tolerance. An essential condition of the present invention is the steps 104 and 110 of the first stage.

FIG. 5 will be described in more detail. First, in step 102, a balancer assembly (including a balance shaft, a balancer gear, and a balance shaft housing) is assembled to a cylinder block via a master shim.
The thickness of the master shim is set to be larger than the thickness of the shim 4 actually mounted on the engine so that the measurement backlash does not become zero or less.

Next, at step 104, the amount of backlash between the crank gear 20 and the balancer gear 22 is determined for the balancer assembly assembled via the master shim.
The measurement is performed at four points shown in FIG. That is, the crank angle 3
The amount of backlash is measured at a total of four points: two points at the crankshaft maximum deceleration points of 0 ° and 210 °, and two nearest points to the crankshaft of the unbalance mass at crank angles of 100 ° and 280 °.

The method of measuring the backlash is to measure how much one of the crank gear 20 and the balancer gear 22 is restrained from rotating and the other moves in the circumferential direction at a gear pitch circle equivalent diameter within the range of the backlash. It does by doing. The measurement is performed by expanding the gear rotation with a lever and measuring the amount of movement of the lever tip with a dial gauge.

Next, at step 106, it is determined whether or not the variation width of the backlash value (the maximum value of the backlash value−minimum value) at the above-mentioned four measurement points is within a predetermined tolerance (for example, 66 microns). Is determined. If within the allowable value, proceed to step 110,
If the allowable value is exceeded, the balancer is determined to be defective in step 108, another balancer is selected for balancer rearrangement, and the process returns to step 102 again.

In step 110, a target shim for setting the backlash of the point showing the minimum value of the backlash value at the point showing the minimum value of the backlash value among the four measurement points to the target value is determined. For example, if four backlash values measured using a master shim are 125 microns, 130 microns, 145 microns, and 150 microns, and a target value is 30 microns, a point indicating a minimum value of 125 microns. In order to make the backlash value of 30 microns, the target shim 4
The backlash value is 95 microns (= 1) from the master shim.
It is only necessary to select a thin shim that is reduced by 25-30 microns. Thus, the target shim is determined. Next, at step 112, the master shim is replaced with the target shim. Thereby, the minimum backlash can be set to the target value.

Then, the process proceeds to step 114 of the second stage, where the cylinder block 2 and the balancer housings 6 and 8 are moved.
The backlash between the crank gear 20 and the balancer gear 22 in the case where the target shim 4 is interposed between them is measured again at the four measurement points. Then, in step 116, the adjusted backlash value of the point (target point) showing the minimum backlash value falls within a range of a target value (30 microns in the above example) ± a constant value (for example, 24 microns). If it is not within this range, there is a problem in the selection of the target shim, so the routine proceeds to step 118, replaces the target shim with another shim, and returns to step 114 again.

In step 120, it is confirmed whether or not the backlash of points other than the target point out of the four measurement points is within an allowable value. For example, it is checked whether the maximum deceleration point of the crankshaft is within the range of 5 to 105 microns, and whether the point closest to the mass is within the range of 15 to 135 microns. If it is within this range, it is considered that the backlash adjustment is completed, and the process proceeds to step 122, where the backlash adjustment of the balancer is completed. If it is not within the range, the process proceeds to step 118 to replace the target shim with another shim. The process returns to step 114 again.

In the above-described backlash adjustment, the time required for the backlash adjustment and the determination of the target shim in steps 104, 106 and 108 of the first stage is about 45.
Second, steps 114, 116, 1 of the second stage.
The time required for confirmation of 20 is about 45 seconds, which is a short time, so that the balancer can be assembled and the backlash can be adjusted in the engine assembly line.

[0029]

The effects of the above-described backlash adjusting method are as follows. First, normally, a target value cannot be set small in consideration of variations in processing accuracy (for example, when an average value is used). However, a target value can be set small because a minimum value is used. The smaller the variation, the smaller the backlash, so that the backlash setting of the product becomes smaller and the rattle can be effectively suppressed. Second
By directly managing the rattle noise generation point (two points at the crankmost deceleration point) and the danger point on gear reliability (two points at the mass nearest point), it is possible to effectively control rattle noise and prevent gear breakage. Can be done.

Third, in order to adjust the backlash at the point indicating the minimum value of the four measurement points to the target value, the backlash due to the variation of the backlash at the four points when the machining accuracy of the gear is poor is reduced to zero or less. Occurrence can be prevented. 4th
In addition, since the number of measurement points is as small as four and replacement of the master shim with the target shim is usually performed only once, backlash adjustment can be performed in a relatively short time, and the engine can be incorporated into an engine assembly line.

[Brief description of the drawings]

FIG. 1 is a front view of a crank gear and a balancer gear showing measurement points of a backlash adjusting method for a gear driven balancer of the present invention.

FIG. 2 is a diagram showing the relationship between crank rotation fluctuation, the rotational position of an unbalance mass of a balance shaft, and the generation timing of rattle sounds, showing the analysis state of rattle sounds.

FIG. 3 is a front view of a gear driven balancer according to one embodiment of the present invention.

FIG. 4 is a side view of the device of FIG. 3;

FIG. 5 is a flowchart showing a work order for backlash adjustment.

[Explanation of symbols]

 2 Cylinder block 4 Shim 6 (First) balance shaft housing 8 (Second) balance shaft housing 10 Crank shaft 12 Balance shaft 14 Balance shaft 16 Unbalance mass 18 Unbalance mass 20 Crank gear 22 Balancer gear 24 Balancer gear

────────────────────────────────────────────────── (5) References JP-A-59-226762 (JP, A) JP-A-59-133845 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16F 15/26 F16H 55 / 18,57 / 12 F02B 77/00

Claims (1)

(57) [Claims] 1. A backlash adjusting method for a gear-driven balancer in which a balance shaft is rotated twice per rotation of a crankshaft by meshing a crank gear mounted on a crankshaft and a balancer gear mounted on a balance shaft. For each rotation, the two most deceleration points of the crankshaft and the nearest point 2 where the unbalance mass of the balance shaft comes closest to the crank gear
The backlash is measured at a total of four points, and the distance between the axes of the crank gear and the balancer gear is adjusted so that the backlash at the point showing the minimum backlash value among the four points becomes the target value. Backlash adjustment method for a gear-driven balancer, wherein a backlash is determined.