JPH0449565Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a contact pressure detection device, and is useful for accurately adjusting the valve clearance between a rocker arm and a valve cap in an automobile engine.

FIG. 1 shows the upper part of a valve system in an automobile engine. In the figure, 1 is a valve stem, 2 is a valve cap, 3 is a valve spring, 4 is a rocker arm, 5 is a push rod, 6 is an adjusting screw, and 7 is a lock nut. A valve shaft (not shown) is provided at the lower end of the valve stem 1, and the cylinder is opened and closed by moving the valve stem 1 up and down. The valve stem 1 is urged upward by a double valve spring 3, and when the valve closes a cylinder and is caught by the cylinder, its upward movement is restricted. The rocker arm 4 swings when pushed by the push rod 5. The rocker arm 4 swings and pushes the valve cap 2 downward against the spring force of the valve spring 3, thereby opening the cylinder.

In such a valve device, the valve stem 1 is biased by the valve spring 3 and positioned at the uppermost end, and
When the rocker arm 4 is not pushed by the push rod 5, a gap (valve clearance) is created between the rocker arm 4 and the valve cap 2. This valve clearance must be adjusted accurately. This is because if the valve clearance deviates from the appropriate value, exhaust gas will deteriorate and engine performance will deteriorate.
To adjust the valve clearance, first turn the adjusting screw 6 to change the rocking position of the rocker arm 4, thereby adjusting the valve clearance to an appropriate value. Next, when the valve clearance reaches a proper value, tighten the lock nut 7 to fix the rotation of the adjusting screw 6 and prevent the valve clearance from shifting.

Conventionally, to detect whether the valve clearance is at an appropriate value, a thin plate called a thickness gauge with a constant thickness (for example, 0.3 mm) has been used. Specifically, the thickness gauge is sandwiched between the valve cap 2 and the rocker arm 4. Then, contact pressure is applied to the thickness gauge by the spring force of the valve spring 3. When an operator pulls out the thickness gauge in this state, the operator feels a pulling force proportional to the contact pressure. The worker's sense of this pulling force determines whether the valve clearance is appropriate. This takes advantage of the fact that when the thickness gauge is pulled out, the valve cap 2 moves upward a little and then stops, creating a valve clearance between the valve cap 2 and the rocker arm 4. In other words, by utilizing the fact that when the pull-out force, or contact pressure, is large, the valve clearance created after pulling out the thickness gauge is small, and conversely, when the pull-out force is small, the valve clearance created after pulling out the thickness gauge is large. There is.

However, since this conventional technique relies on the operator's sense of force, not only does it require skill, but the accuracy of the valve clearance sometimes varies. SUMMARY OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide a contact pressure detection device that is useful for accurately adjusting the valve clearance of an engine, for example, by accurately detecting contact pressure. The structure of the present invention that achieves this object includes a thin plate sandwiched between two members that are biased toward each other, and a thin plate that is fixed to the thin plate and transmits ultrasonic waves to the thin plate and transmits ultrasonic waves within the thin plate. The energization is performed by an ultrasonic probe that captures the reflected ultrasonic waves and a display means that detects the magnitude of the amplitude of the reflected ultrasonic waves captured by the ultrasonic probe and displays the magnitude. The present invention is characterized in that it is configured to detect the contact pressure between the two members holding the thin plate.

Embodiments of the present invention will be described in detail below with reference to the drawings. Note that parts that are the same as those in the prior art are given the same numbers and redundant explanations will be omitted.

FIG. 2 shows an embodiment of the invention. As shown in the figure, an ultrasonic probe 11 is fixed to a thickness gauge 10 held between a valve cap 2 and a rocker arm 4. The ultrasonic probe 11 generates ultrasonic waves, and the ultrasonic waves are transmitted to the thickness gauge 10.
At the same time, the ultrasonic waves reflected within the thickness gauge 10 are captured. The reflected ultrasonic waves become smaller as the contact pressure applied to the tightness gauge 10 becomes higher. Specific characteristics are shown in Figure 3. In the contact pressure detection device of the present application, the ultrasonic waves generated by the ultrasonic probe 11 are transmitted to the thickness gauge 10, and a part of the ultrasonic waves propagated through the thickness gauge 10 is transmitted to the thickness gauge 10. The remaining ultrasonic waves are transmitted to the Rocker arm 4 and valve cap 2 that are holding it in place, and the remaining ultrasonic waves are transmitted to the Rocker arm 4 and valve cap 2.
Thickness Gauge 10 by reflecting without being transmitted to
The ultrasonic waves traveling in the opposite direction and reflected are captured by the ultrasonic probe 11. In this case, as the contact pressure for clamping the thickness gauge 10 increases, the amount of ultrasonic waves transmitted to the rocker arm 4 and the valve cap 2 increases, and the amount of ultrasonic waves that are reflected back to the rocker arm 4 and the valve cap 2 decreases. Conversely, when the contact pressure decreases, the amount of ultrasonic waves transmitted to the rocker arm 4 and valve cap 2 decreases, and the amount of ultrasonic waves reflected back increases. The display device 12 converts the amplitude of the reflected ultrasound captured by the ultrasound probe 11 into an electrical signal, displays the magnitude of the reflected ultrasound on a screen 12a, and indicates when the magnitude of the reflected ultrasound reaches a set value. Turn on the lamp 12b. The setting value mentioned here is, for example, 34 in Figure 3.
[%], and in this case, the contact load is 34.8 [Kg]. When the thickness gauge 10 is pulled out when the contact load is 34.8 kg, the valve clearance becomes the optimum value.

The controller 13 receives signals from the display device 12 and controls the nut runner 14 . In other words, when the intensity of the reflected ultrasonic wave is small, the nut runner 14 causes the adjusting screw 6 to
Turn to increase the contact pressure. When the intensity of the reflected ultrasonic wave reaches, for example, 34%, the rotation of the adjusting screw 6 is stopped by the nut runner 14, and the lock nut 7 is tightened. As a result, the rotation of the adjusting screw 6 is fixed. Since the intensity of the reflected ultrasound was fixed at 34%, the contact load was 34.8Kg. Therefore, if the thickness gauge 10 is pulled out in this state, the valve clearance will be optimized.

In this manner, in this embodiment, the adjusting screw 6 can be rotated to a contact pressure that optimizes the valve clearance, and the valve clearance can be automatically adjusted with high precision. Note that the adjusting screw 6 may be rotated by the operator while looking at the display device 12 without using the controller 13 and the nut runner 14. Furthermore, instead of the display device 12, a device that indicates the intensity of reflected ultrasound waves with sound may be used.

As specifically explained above in conjunction with the embodiments, according to the present invention, accurate contact pressure can be detected. Therefore, the valve clearance in the valve device can be adjusted with high precision.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the upper part of a valve device in an automobile engine, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is a characteristic diagram showing the relationship between the intensity of reflected ultrasonic waves and contact load. be. In the drawing, 2 is a valve cap, 4 is a rocker arm, 10 is a thickness gauge (thin plate), 11 is an ultrasonic probe, and 12 is a display device.

Claims (1)

[Scope of utility model registration request] A thin plate sandwiched between two members that are biased toward each other, and an ultrasonic probe that is fixed to this thin plate and transmits ultrasonic waves to the thin plate and captures the ultrasonic waves that are reflected within the thin plate. and display means that detects and displays the amplitude of the reflected ultrasonic waves captured by the ultrasonic probe, so that the two biased members clamp the thin plate. A contact pressure detection device characterized by being configured to detect contact pressure.