JPS58153125A - Vibration detector - Google Patents

Abstract

PURPOSE:To prevent the parasitic vibration at the contact plane between a connector and a case, by providing a vibration absorbing material at the part where the case is connected with a lid material as the connector. CONSTITUTION:Annular rubber 10 is provided at a shelf part 1d of the case 1 and the peripheral part of an opening part 1b. A flange part 7b of the connector 7 is provided on the rubber 10 so as to cover the opening part 1b. The peripheral part of the opening part 1b is bent so as to push the peripheral part of the flange part 7b to the shelf part 1d through the rubber 10. Therefore, the parasitic vibraton at the contact plane of the end parts 7b and 1d of the connector 7 and the case 1 is absorbed and prevented by the annular rubber 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present ff11M relates to a vibration detector, and particularly relates to a vibration detector that detects slight engine knocking.

In internal combustion engines, combustion efficiency improves when the ignition timing is advanced, but knocking occurs when the ignition timing is advanced. Therefore, slight engine knocking is detected as an electrical signal by a vibration detector, and the ignition timing is controlled based on this signal to prevent the occurrence of serious knocking that would adversely affect the engine.

A conventional example of such a vibration detector will be explained with reference to FIG.

In FIG. 1, a case 1 has a mounting screw 1a, and a cup-shaped opening lb at the head of the screw 1a. Furthermore, a hexagonal tightening corner portion 1C is formed on the outer periphery of the case 1. Two piezoelectric elements 2a, 2 are placed inside the opening lh.
h are provided to sandwich the electrode terminals 3. A weight 4 is located above the piezoelectric elements 2Q, 2A, and a port 5 presses and fixes the piezoelectric elements 2a, 2b against the case 1 from above the weight 4. An insulating link 6 is provided between the threaded portion of the bolt 5 and the piezoelectric elements 2a, 2A. Further, a shelf 1d is provided within the opening lh of the case 1, and a connector 7 is provided on the shelf 1d so as to cover the opening 1b. The connector 7 is
It consists of a cylindrical connecting part 7a, a flange part 7h disposed on the shelf part 1d, and a terminal pin 7c embedded in the center of the flange part 7h and having a tip portion protruding into the cylinder of the connecting part 7α. Become. The peripheral edge of the opening lh is the flange portion 7
The peripheral edge of h is bent so as to be pressed against the shelf 1d, and is so-called tightened. In addition, terminal pin 7
C and the electrode terminal 3 are electrically connected by a lead wire 8. Further, the space inside the opening lb is filled with a resin 9 such as a soft resin to maintain airtightness.

In a vibration detector having such a configuration, a screw 1α is screwed into a screw hole provided in a vibrating body (not shown) such as an engine block of an engine, and the vibration of the vibrating body is transmitted to the piezoelectric element 2.
When transmitted to the piezoelectric elements 2α and 2h, a potential difference is generated between the front and back surfaces of the piezoelectric elements 2α and 2b. This potential difference is detected between the terminal pin 7c of the connector 7 and the case 1 via the lead wire 8.

Further, in this vibration detector, the connecting portion 7α and the flange portion 7h of the connector 7 are made of synthetic resin in order to insulate the terminal via 7c from the case 1. However, when the connector 7 is fixed by caulking the peripheral edge of the opening 1h as described above, the elasticity of the synthetic resin is small and the initial load of caulking cannot be sufficiently large, and if the usage time is prolonged, the synthetic resin and the opening will be damaged due to vibration. The caulked portion of the peripheral edge of the connector 1h is deformed, and the connection between the connector 7 and the case l becomes loose. In such a loose state, parasitic vibration occurs at the contact surface between the connector 7 and the case 1, so that the output voltage waveform of the vibration detector has a peak due to the parasitic vibration in a frequency band that should originally have a nearly flat characteristic. There was a problem that it became a characteristic that it had.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vibration detector configured to prevent parasitic vibrations at the contact surface between a connector and a case.

In the vibration detector according to the present invention, a vibration absorbing material is provided at a portion where a case and a lid member serving as a connector are in contact with each other.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3.

In FIG. 2, an annular rubber 10 is provided at the peripheral edge of the shelf ld and the opening 1h of the case 1.
The flange portion 7b of the connector 7 is provided on the opening 1b so as to cover the opening 1b, and the flange portion 7b of the connector 7 is placed on the opening 1 so as to press the peripheral edge of the flange portion 7h against the shelf portion 1d via the rubber 10.
The peripheral edge of h is bent. The rest of the structure of the vibration detector according to the present invention is the same as that of the conventional example shown in FIG. 1, so the description thereof will be omitted here.

In the vibration detector according to the present invention having the above configuration, a rubber 10 is used which absorbs the force due to the maximum vibration acceleration applied to the case l. As a result, the bonding force between the connector and the case 1 can be maintained even if the usage time becomes long because the rubber 10 absorbs the vibrations applied to the tightened part. Vibration is suppressed. Therefore, as shown in FIG. 3, the output voltage characteristic (solid line A) of the vibration detector according to the present invention has a frequency band f, in which non-king occurs, compared to the conventional characteristic (broken line B) that has a peak due to parasitic vibration at the frequency fα. The characteristic is almost flat at f2. Furthermore, the peak at frequency fh due to resonance vibration based on the natural frequency of the connector 7 itself is also reduced compared to the conventional case.

As described above, the vibration detector according to the present invention is provided with a vibration absorbing material that absorbs vibrations applied to the clamping joint between the case and the connector, thereby suppressing parasitic vibration at the contact surface between the case and the connector. It is possible.

In addition, in the vibration detector according to the present invention, parasitic vibrations are suppressed by providing an elastic member such as a disc spring or a wave washer at a position that resists the pressing force due to caulking of the caulking joint between the case and the connector together with the vibration absorbing material. It is also possible to further improve the effect of 8.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional example of a vibration detector, FIG. 2 is a sectional view showing an embodiment of the vibration detector of the present invention, and FIG. 3 is an output voltage characteristic diagram of the vibration detector. Explanation of symbols of main parts 1...Case 2α, 2b...Piezoelectric element 3
... Electrode terminal 4 ... Weight 5 ... Port 6 ... Insulation link 7 ... Connector
8...Lead wire 10...Rubber applicant Japan Electronics Co., Ltd. agent Patent attorney Rattan material Motohiko

Claims (2)

[Claims] (1) A case having a converting means that generates an electric signal according to a vibration level, a mounting part attached to the vibrating body on the outside, and an opening for storing and holding the converting means, and an opening of the case. and a lid member that holds a conductor that is fastened and electrically connected to the output end of the converting means, and a vibration absorbing material is provided at a portion where the case and the lid member are in contact with each other. Detector. (2) The opening is provided with a shelf, and the peripheral edge of the opening is bent so as to press the peripheral edge of the lid member against the shelf. The vibration detector according to item 1.