JP2827829B2 - Belt tension inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt tension inspection apparatus for inspecting the tension of an engine timing belt or the like.

[0002]

2. Description of the Related Art An engine for an automobile transmits the rotational motion of a crankshaft to an auxiliary device such as a camshaft or a water pump via a timing belt, and the tension of the belt falls within a predetermined allowable range. Need to be. For this reason, a process for checking belt tension is provided in an engine assembly process and the like. Conventionally,
As a means for performing such belt tension inspection, a load in a direction in which the belt is bent by the weight is applied to an intermediate portion between the belt pulleys, for example, a weight method, and the weight of the weight and the bending of the belt are used. Based on quantity,
It is determined whether the tension is appropriate.

[0003]

However, in the above-described conventional tension inspection means, not only takes time to set up a weight on the belt and measures the deflection of the belt, but also the magnitude and the tension of the deflection are reduced. It did not always correspond exactly, and it was difficult to obtain an accurate tension measurement value. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a tension inspection device capable of efficiently and accurately inspecting whether or not a belt tension is appropriate.

[0004]

SUMMARY OF THE INVENTION The present invention, which has been developed to achieve the above object, is an apparatus for checking the tension of a belt stretched between pulleys. Air hammer mechanism for hitting, frequency detecting means for detecting the frequency of vibration generated in the hit belt, and determining whether the frequency detected by the frequency detecting means is within a predetermined reference value range. And determining means for determining that the tension is appropriate when the frequency is within the reference value range, and display means for displaying a determination result by the determining means, wherein the air hammer mechanism faces the belt. Piston having an air chamber for accommodating the piston movably in the axial direction and receiving compressed air for pushing the piston. A cylinder having an escape hole for releasing air in the air chamber when the air chamber advances, an air supply source for supplying compressed air to the air chamber, and an air flow path from the air supply source to the air chamber. The provided primary-side on-off valve, the check valve provided on the downstream side of the primary-side on-off valve, the secondary-side on-off valve provided on the downstream side of the non-return valve, and the secondary-side on-off valve And a pressure accumulating conduit for confining a fixed amount of compressed air between the check valve and the secondary-side on-off valve in a closed state.

[0005]

The inspection device of the present invention drives the piston of the air hammer mechanism with compressed air to strike the belt, and detects the tension of the belt by detecting the frequency of vibration generated in the belt. This inspection device opens the primary-side on-off valve and closes the secondary-side on-off valve in a preparatory stage before driving the piston, so that the compressed air supplied from the air supply source is returned to the check valve and the It is supplied to the accumulator line between the valve and the on-off valve. Then, by closing the primary side on-off valve, a fixed amount of compressed air is confined in the accumulator line. In this state, when a signal instructing the start of the inspection is input, the secondary side on-off valve is opened, and a certain amount of compressed air trapped in the accumulator is released in a direction to push out the piston. The tip of the piston jumps out toward the belt.

When the tip of the protruding piston collides with the belt, the belt is bent by the kinetic energy of the piston, and the piston is rebounded by the elastic restoring force of the belt. The rebounded piston is returned into the cylinder at a speed close to the initial speed. At this time, since the air in the cylinder and the air in the accumulator are already discharged, the piston does not jump out again and stays at the initial position inside the cylinder.

[0007] When the piston rebounds, the belt also returns in the same direction as the piston, but since the belt is under tension, the belt moves at a lower speed than the piston. Therefore, the belt bends by a certain amount without touching the piston, and then attenuates while repeating a behavior of bending back again in the opposite direction. That is, the belt vibrates at a natural frequency corresponding to the magnitude of the tension.

The frequency of the vibration is detected by a vibration detecting means using an acceleration pickup or an FFT analyzer as an example of a vibration sensor, and the frequency falls within a predetermined reference value range by a discriminating means such as a microcomputer. It is determined whether the belt tension is appropriate or not, and if it is within the reference value range, it is determined that the belt tension is appropriate and displayed by the display means.

In the above-described air hammer mechanism, the amount of compressed air that pushes out the piston depends on the capacity of the pressure accumulation line between the secondary side on-off valve and the check valve. By appropriately setting the capacity of the pressure accumulating pipeline in accordance with the above, it is possible to obtain a piston pop-out force that gives a vibration suitable for a tension test. Further, since the return speed of the piston after hitting the belt is fast and the piston quickly fits into the cylinder, the belt is prevented from hitting twice.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a crankshaft pulley 11 and a camshaft pulley 12,
Water pump pulley 13, tension pulley 14, 1
5 and the like are provided. These pulleys 11 to 15
Is in the form of a sprocket as required.
A timing belt 17 is stretched over each of the pulleys 11 to 15, and the torque of the crankshaft pulley 11 is transmitted to the camshaft pulley 12, the water pump pulley 13, and the like via the belt 17.

An inspection device 20 for inspecting the tension of the belt 17 includes an air hammer mechanism 21 for hitting the belt 17.
A frequency detecting means 22 for detecting a frequency of vibration generated in the beaten belt 17, a control section 23 using a microcomputer or the like built in a control panel or the like;
4 and so on.

The air hammer mechanism 21 has a pitching unit 30. The pitching unit 30 includes a hollow cylindrical cylinder 31 and a cylindrical piston 32 accommodated in the cylinder 31. The cylinder 31 is provided on the base 35 with the tip 31a side obliquely facing upward, and the tip 36 of the piston 32 is connected to the pulleys 11, 1.
An intermediate portion of the belt 17 between the three belts is opposed to a central portion of the belt 17 in the width direction. The piston 32 is movable in the axial direction of the cylinder 31, and when the piston tip 36 jumps out toward the belt 17, the
The center of the width direction is hit.

As shown in FIG. 2, the piston 32 is supported by a bearing 40 such as a linear ball bearing so as to be able to move smoothly in the axial direction of the cylinder 31. The bearing 40 is held at a predetermined axial position by a retaining ring 41. The piston 32 in the illustrated example is made of a metal having a relatively small specific gravity, such as an aluminum alloy, and its surface including the outer peripheral portion is subjected to a surface hardening treatment such as hard alumite. Since the piston 32 is accommodated in the cylinder 31 facing obliquely upward, in a free state, the piston 32 is retracted by its own weight toward the rear end 31b of the cylinder 31.

A stopper 45 is provided on the inner surface of the cylinder 31. A flange 46 having an outer diameter larger than the inner diameter of the stopper 45 is provided at the rear end of the piston 32. Therefore, the piston 32 has a tip portion 36.
Is projected from the cylinder 31 by a predetermined length, the flange portion 46 hits the stopper portion 45 so that it does not move further forward. Flange part 46
On the rear side, an air chamber 47 into which compressed air is introduced and a connector 48 for connecting an air pipe are provided.

The cylinder 31 is provided on the side wall 50 of the cylinder 31.
1st air escape hole 5 consisting of a long hole extending in the axial direction of
1 and a second air release hole 52 located behind the air release hole 51. The first and second air release holes 51 and 52 are respectively provided in the cylinder 31
The air in the air chamber 47 can be discharged to the outside of the cylinder 31 when the piston 32 advances to some extent.

A driving section 55 for driving the piston 32 by compressed air is configured as shown in FIG. That is, the driving unit 55 is
And an electromagnetic primary side opening / closing valve 57 provided in the middle of an air flow passage from the air supply source 56 to the air chamber 47.
And a check valve 58 provided downstream of the primary-side on-off valve 57.
And an electromagnetic secondary on-off valve 59 provided downstream of the check valve 58, a speed control mechanism 60 provided downstream of the secondary on-off valve 59, and the like. The speed control mechanism 60 includes a check valve 61 and a variable throttle valve 62. The moving speed of the air flowing in the direction of the air chamber 47 can be adjusted by adjusting the cross-sectional area of the throttle valve 62.

The check valve 58 allows air to flow in the direction from the primary open / close valve 57 to the secondary open / close valve 59, and is provided between the check valve 58 and the secondary open / close valve 59. To
An accumulator line 65 of length L is provided. When the secondary side opening / closing valve 59 is closed, the pressure accumulation pipeline 65 is configured to confine a fixed volume of compressed air in accordance with the pipe length L and the pipe diameter. An example of the pipe length L is 30 mm and an example of the pipe diameter is 8 mm, but it is needless to say that these values are appropriately changed according to the required compressed air capacity.

As shown in FIG. 1, the frequency detecting means 22
Is composed of an acceleration pickup 71 as an example of a vibration sensor having a probe 70 facing the belt 17, an FFT analyzer 72 for obtaining a vibration frequency based on an acceleration signal sent from the acceleration pickup 71, and the like. The acceleration pickup 71 can advance and retreat toward the belt 17 by a driving mechanism 73 such as an air cylinder.

Control unit 2 using microcomputer or the like
An operation panel 24 is connected to 3. The operation panel 24 includes switches 75 capable of transmitting a signal or the like for starting an inspection,
A display unit 76 such as a lamp or a buzzer is provided as an example of a display unit that displays an inspection result. The control unit 23 controls the on-off valves 57 and 59, controls the acceleration pickup 71 and the FFT analyzer 72 in a processing procedure as illustrated in FIG. A determination step S1 or the like as determination means for determining whether or not there is is programmed.

Next, the operation of the tension inspection apparatus 20 having the above configuration will be described with reference to FIG. Piston 3
In a preparatory stage before the second valve 2 is driven, the secondary side on-off valve 59 is closed. When the primary open / close valve 57 is opened, the compressed air supplied from the air supply source 56 is supplied to the pressure accumulating pipeline 65 through the primary open / close valve 57 and the check valve 58. After that, by closing the primary side on-off valve 57,
A certain amount of compressed air is confined in the pressure accumulation line 65.

When a signal instructing the start of the inspection is input to the controller 23, the acceleration pip-up 71 is advanced toward the belt 17 by the drive mechanism 73, and the probe 70
When the tip of the FFT analyzer 7 contacts the belt 17, the FFT analyzer 7
The second trigger is turned on, and the secondary-side on-off valve 59 is opened. As a result, a certain amount of compressed air that has been confined in the pressure accumulating pipe 65 until then passes through the speed control mechanism 60 and the air chamber 47 of the pitching unit 30.
And the distal end portion 36 of the piston 32 pops out as shown in FIG. This piston tip 36
Collides with the belt 17, the belt 17 bends and the elastic restoring force of the belt 17 causes the piston 32
Is bounced back in the original direction.

When the piston 32 jumps out as described above,
Since the air in the pressure accumulation pipe 65 and the air in the air chamber 47 are released to the outside through the escape holes 51 and 52, the piston 3
When 2 bounces, no air remains to hinder the movement of the piston 32. For this reason, the piston 32 returns to the inside of the cylinder 31 at a speed close to the initial speed at the time of the rebound, and no force for flying the piston 32 is generated again.

As described above, when the piston 32 collides with the belt 17 and rebounds, the belt 17 also tries to return in the same direction as the piston 32. When it returns, it comes back to the opposite side again. Thus, the belt 17
Causes a periodic reciprocating motion and vibrates at a frequency corresponding to the magnitude of the tension.

The frequency at which the belt 17 vibrates is detected by the acceleration pickup 71 and the FFT analyzer 72, and the control unit 23 determines whether or not the frequency falls within a predetermined reference value range in a determination step S1. . If the frequency falls within the reference value range, it is determined that the tension is appropriate. The reference frequency range is, for example, from 126 Hz to 156 Hz, but it goes without saying that this value is appropriately changed according to the specifications of the engine 10 and the belt 17 to be inspected.

After it is determined whether the tension of the belt 17 is appropriate, the acceleration pickup 71 is retracted to the original position by the drive mechanism 73, the secondary open / close valve 59 is closed, and the primary open / close valve 57 is opened. As a result, after a predetermined amount of compressed air is replenished from the air supply source 56 to the pressure accumulating conduit 65 again, the primary side opening / closing valve 57 is closed.

With the air hammer mechanism 21 having the above structure,
The amount of compressed air that drives the piston 32 of the pitching unit 30 substantially depends on the capacity of the pressure accumulation pipe 65. That is, by appropriately setting the capacity of the pressure accumulation pipe 65, it is possible to set the piston pop-out force and the rebound force suitable for vibration detection, and the air escape holes 51,
Combined with the provision of 52, it is possible to prevent the belt 32 from hitting the belt 17 twice.

The air supplied from the air supply source 56 may be a gas obtained by compressing the atmosphere as it is, or may be a gas obtained by mainly compressing a specific component such as nitrogen. In the above embodiment, the rebound resilience of the belt 17 and the weight of the piston 32 are used as means for returning the piston 32 to the initial position. However, in some cases, the return spring is used to move the piston 32 in the direction of the initial position. May be restored. Further, the present invention can be used for a tension test of belts other than the timing belt.

[0028]

According to the present invention, a vibration suitable for frequency detection can be given to the belt without hitting the belt twice, and the belt tension can be adjusted based on the frequency of the vibration generated in the belt. Compliance can be quickly and accurately determined.

[Brief description of the drawings]

FIG. 1 is a schematic view of a tension inspection apparatus showing one embodiment of the present invention.

FIG. 2 is a sectional view of a pitching unit of the inspection apparatus shown in FIG.

FIG. 3 is a diagram showing a piping system of a pitching unit drive unit of the inspection device shown in FIG.

FIG. 4 is a plan view of a cylinder of the pitching unit of the inspection device shown in FIG.

FIG. 5 is a cross-sectional view showing a state where a piston of the inspection device shown in FIG. 1 has advanced.

FIG. 6 is a flowchart showing the operation of the control unit of the inspection device shown in FIG.

[Explanation of symbols]

11, 12, 13 ... pulley, 17 ... belt, 20 ... tension inspection device, 21 ... air hammer mechanism, 22 ... frequency detection means, 23 ... control unit, 30 ... pitching unit, 31 ...
Cylinder, 32 ... piston, 47 ... air chamber, 51, 52
.., An air release hole, 56, an air supply source, 57, a primary open / close valve, 58, a check valve, 59, a secondary open / close valve, 65, a pressure accumulating pipeline.

Claims (1)

(57) [Claims] An apparatus for inspecting the tension of a belt stretched between pulleys, comprising: an air hammer mechanism for striking a portion between the pulleys of the belt; and a vibration frequency generated in the struck belt. Frequency detecting means for detecting, and judging whether or not the frequency detected by the frequency detecting means is within a predetermined reference value range, and when the frequency is within the reference value range, the tension is appropriate. Determination means, and a display means for displaying a determination result by the determination means, wherein the air hammer mechanism includes a piston disposed opposite to the belt, and the piston movably in the axial direction. It has an air chamber into which compressed air for accommodating and pushing the piston is sent, and has a relief hole for releasing air in the air chamber when the piston advances. A cylinder, an air supply source for supplying compressed air to the air chamber, a primary open / close valve provided in the middle of an air flow passage from the air supply source to the air chamber, and a primary open / close valve. A check valve provided on the downstream side, a secondary open / close valve provided on the downstream side of the check valve, and the check valve and the secondary open / close in a state where the secondary open / close valve is closed. A pressure accumulation line for confining a fixed amount of compressed air between the valve and the valve.