JP2993073B2 - How to correct engine crankshaft balance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Industrial Field of the Invention The present invention relates to a method for correcting the balance of a crankshaft of an engine of a car, a motorcycle, an outboard motor or the like.

b. Prior art Crankshaft balance can be corrected by drilling the crankshaft and changing the mass distribution.

FIG. 1 is a front view of a crankshaft that has been drilled to correct the balance, and FIG. 2 is a cross-sectional view of the drilled portion when the crankshaft with the corrected balance is viewed from the axial direction.

FIG. 3 is a diagram showing the relationship between the balance deviation B of the crankshaft and the balance correction amount in vector.

Assuming that the mapping of the crankshaft balance deviation B to the axes a and b is Ba and Bb, the balance of the crankshaft can be obtained by drilling the axes a and b by an amount corresponding to Ba and Bb.

However, the correction efficiency decreases as the axis approaches the axis of the crankshaft, and the depth of correction is limited due to the function of the crankshaft. In such a case, drilling is further performed on axes c and d that are shifted from the axes a and b by an angle そ れ ぞ れ, respectively.

FIG. 9 is a flowchart of a method for correcting the balance of the crankshaft.

The balance deviation of the crankshaft sent from the previous process is obtained by a balance measuring machine. Its size B
Is smaller than the predetermined value A, if B ≧ 0, it is sent to the next step, and if B <0, it is discarded as a defective NG. When the size B is larger than the predetermined value A, drilling is performed on the axes a and b in FIG. 2 according to the deviation.

Thereafter, the balance deviation is measured again by the balance measuring machine. If the size B 'is smaller than the predetermined value A, the process is sent to the next step if B'≥0, and is discarded as a defective NG if B'<0. When the size B 'is larger than the predetermined value A, drilling is performed on the axes c and d in FIG. 2 according to the deviation. The angle θ between the axes c and d is equal to the angle θ between the axes a and b.

FIG. 7 is a conceptual diagram of an automatic crankshaft balancing machine. The crankshaft is a balance measuring machine 2
The deviation from the balance state is measured in the above, and the crankshaft 1 in which the deviation is measured is sent to the balance correcting machine 4 by the rotary conveying device 3 and the drill unit 5 determines the predetermined position, that is, the axis a, in FIGS. In b, drilling is performed to a depth corresponding to the above deviation. If necessary, the crankshaft 1 is returned to the balance measuring device 2 by the rotary transfer device 3, the balance is measured, and the rotary shaft is returned to the correction device 4 by the rotary transfer device 3 again. Drilling is performed in d to further correct the balance.

FIG. 8 is a conceptual diagram of a transfer type crankshaft automatic balancing machine. The deviation from the balance state of the crankshaft 1 is measured by a first balance measuring machine 2a, and a drilling process is performed by a drill unit 5a of a first balance correcting machine 4a based on the measurement result. The deviation from the balance state is measured by the measuring device 2b, and based on the result, the second balance correcting device is used.
Drilling is performed by a drill unit 5b of 4b, and a deviation from the balance state is finally inspected by a third balance measuring machine 2c.

c. Problems to be Solved by the Invention The deviation B from the balance state of the crankshaft is represented by axes a,
When correcting by drilling in b, the component Ba of the deviation B in the direction of the axis a exceeds the maximum correctable amount Ma in the direction of the axis a, and the component Bb in the direction of the axis b can be corrected in the direction of the axis b.
May not exceed Mb. FIG. 4 shows that the axis a is drilled up to the correction possible limit Ma and the component in the axis a direction is Ba.
As Ma, the component Bb of the deviation B in the direction of the axis b with respect to the axis b
Of the deviation D from the balance state of the crankshaft after drilling until it becomes zero, the components D in the directions of the axes c and d.
This is a diagram in which c and Dd are displayed in a vector.

The component of the deviation D in the direction of the axis a is Ba-Ma, and the component in the direction of the axis b is 0. Since the axes c and d are deviated clockwise by an angle に 対 し て with respect to the axes a and b, the components Dc and Dd of the deviation D in the directions of the axes c and d are, as shown in the figure, Dc> 0, Dd <0.
At this time, the component Dc in the direction of the axis c can be set to 0 by drilling, but the component Dd in the direction of the axis d cannot be corrected by drilling, resulting in a defective product NG.

In order to prevent such a situation from occurring, a certain amount of unbalance amount is always left when the axes a and b are corrected, or correction is always performed by a certain ratio. However, at this time, the drilling amount on the axes c and d increases,
Machine time becomes longer. This may lead to a shortage of factory production capacity.

The present invention provides a balance correction method capable of minimizing the secondary correction amount on the axes c and d while avoiding that secondary correction by drilling on the axes c and d is not disabled. Make it an issue.

d. Means for Solving the Problem The above-mentioned problem is solved by a method of obtaining a deviation B from a balance state of an engine crankshaft and correcting the balance by performing drilling at a predetermined position by an amount corresponding to the deviation. , The deviation B is divided into a first axis a and components Ba and Bb in the direction of the second axis b forming an angle of θ with respect to the axis a, and the component Ba in the direction of the first axis a is When the maximum correctable amount Ma of the direction is not exceeded, the first and second axes a,
Drilling is performed in the first and second axes a and b until the components Ba and Bb in the direction b become zero.
In the case of exceeding the maximum correctable amount Ma in the direction of?, Drilling is performed for the first axis a by the maximum correctable amount Ma, the component in the direction of the first axis a is set to Ba-Ma, and the component in the direction of the second axis b is set. Is drilled by an amount Hb (> 0) smaller than the component Bb to make the component in the second axis b direction Bb-Hb, so that the component in the first axis a direction is Ba-Ma, The component of axis b is Bb−
The components Dc and Dd in the third axis c and the fourth axis d of the deviation vector D, which is Hb, are both positive, and correspond to Dc and Dd in the third axis c and the fourth axis d, respectively. The problem has been solved by a method of correcting the balance of the crankshaft of an engine, characterized in that the components in the third axis c and the fourth axis d directions are made zero by drilling by a certain amount.

e. Operation FIG. 6 is a flowchart of the method for correcting the balance of the crankshaft according to the present invention.

If the components Ba and Bb of the deviation B from the balance state of the crankshaft of the engine in the first and second axes a and b do not exceed the maximum modifiable amounts Ma and Mb of the respective axes, the third and third axes are used. Since there is no need to perform drilling in the directions of the axes c and d, the drilling is performed until the unbalance amounts Da and Db of the respective axes become zero.

When one of Ba and Bb exceeds the maximum correctable amount Ma and Mb, drilling is performed up to the maximum correctable amount, and a part of the component remains on the other axis. FIG. 5 shows this state. Then, drilling is further performed on the third and fourth axes c and d in the same flowchart as that in FIG. 9 to correct the balance of the crankshaft of the engine.

f. Embodiment As shown in FIG. 3, the angle of the vector of the deviation B from the balance state of the crankshaft with the first axis a is φ, and the angle between the first axis a and the second axis is θ. When
The components Ba and Bb of the deviation B in the directions of the first and second axes a and b are represented by the following equations.

Ba = B (cos φ−sin φ cot θ) Bb = Bsin φ / sin θ If Ba exceeds the maximum modifiable amount Ma in the direction of the axis a, drill in the axis a direction by the maximum modifiable amount Ma. In the direction of the axis b, drilling is performed by the correction amount Hb. The deviation from the balance state at this time, that is, the components Da and Db in the directions of the axes a and b of the unbalance amount D are expressed by the following equations.

Da = D (cos φ−sin φ cot θ) −Ma Db = D (sin φ / sin θ) −Hb FIG. 5 shows a vector of the unbalance amount D after such a primary correction. This imbalance amount D
Is quadratic corrected on the third and fourth axes c and d.

The third and fourth axes c and d are deviated from the first and second axes a and b by an angle そ れ ぞ れ, respectively.

The component Da of the unbalance amount D in the direction of the axis a is represented by the third and fourth axes.
The component Dd in the negative direction of the fourth axis d when decomposed into c and d is represented by the following equation.

Dd = Da (sin ψ / sin θ) A component Ed in the direction of the fourth axis d when the component Db of the unbalance amount D in the direction of the second axis b is decomposed into the third and fourth axes c and d.
Has the following relationship with the component Db.

Db = Ed (cosψ + sinψcot (θ−ψ)) In order to be able to correct the balance by drilling in the fourth axis d direction, Ed−Dd ≧ 0. Therefore, the following inequality holds.

Here, since Hb ≧ 0, the following inequality holds.

Therefore, when the deviation B from the balance state of the crankshaft exceeds the maximum correctable amount Ma in the direction of the axis a, drilling is performed in the direction of the axis b in the range Hb satisfying the above inequality in the direction of the axis b. By making a program to perform drilling until the component in the direction of the axis b becomes zero, it is possible to prevent secondary correction by drilling on the axes c and d from being impossible, and furthermore, to prevent secondary correction by the axes c and d. The amount of correction can be minimized.

g. Effect i) When the correction cannot be performed when the primary measurement / correction is shifted to the secondary measurement / correction, an imbalance amount corresponding to the correction cannot be left, and the occurrence of defective products can be minimized.

ii) The number of processing steps in the secondary correction is reduced as compared with the method in which the unbalance amount is uniformly left in the primary correction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a crankshaft that has been drilled to correct balance, and FIG. 2 is a portion of drilling when the crankshaft with corrected balance is viewed from the axial direction. FIG. 3 is a diagram showing the relationship between the deviation B from the balance state of the crankshaft and the balance correction amount as a vector, and FIG. 4 is the balance state of the crankshaft after drilling in the primary correction. 5 is a diagram in which components Dc and Dd in the axes c and d directions of the deviation D from the vector are displayed in a vector, FIG. 5 is a diagram in which the unbalance amount after the primary correction is vector-displayed, and FIG. 6 is a crank according to the present invention. FIG. 7 is a flowchart of a method of correcting shaft balance, FIG. 7 is a conceptual diagram of an automatic crankshaft balancing machine, and FIG. Conceptual view of an automatic balancing machine over the form of the crank shaft, FIG. 9 is a flow chart of a method for correcting the balance of the crankshaft.

Claims (1)

(57) [Claims] 1. A method for correcting a balance by determining a deviation B from a balance state of a crankshaft of an engine and performing drilling at a predetermined position by an amount corresponding to the deviation. Axis a, and a component in the direction of a second axis b that forms an angle of θ with respect to axis a
When the component Ba in the direction of the first axis a does not exceed the maximum modifiable amount Ma in the first direction, the first and second axes a and b are divided.
Drilling is performed in the directions of the first and second axes a and b until the components Ba and Bb in the direction become 0, and the component Ba in the direction of the first axis a determines the maximum modifiable amount Ma in the first axis direction. If it exceeds, the drilling is performed for the first axis a by the maximum correctable amount Ma, the component in the direction of the first axis a is set to Ba-Ma, and the amount Hb (>) is smaller than the component Bb in the direction of the second axis b. 0), the component in the direction of the second axis b is Bb-Hb, and the component in the direction of the first axis a is Ba-Ma, and the component in the direction of the second axis b is Bb-Hb.
The third axis c and the fourth axis d of the deviation vector D which is Bb−Hb
Direction components Dc and Dd are both positive, and the third axis c
A component in the direction of the third axis c and the fourth axis d is made zero by performing drilling on the third axis c and the fourth axis d by an amount corresponding to Dc and Dd, respectively. How to fix the balance.