JPH03142366A - Acceleration sensor - Google Patents

Abstract

PURPOSE:To offer a sensor which is free from quality reduction and is easily built in and attached by fixing a cap covering a sensor main body and a wiring connector by an attaching bolt of a sensor base and connecting each lead pin of the main body part and each terminal of the connector and sealing up the connection part with a resin. CONSTITUTION:A metallic cap 34 whose upper face an attaching bolt 35 unified with a spanner reception hexagonal shaft 52 into one body is fixed to by welding is fixed to a base 51 by its peripheral edge flange 35. A wiring connector 56 where a bracket 57 and terminals 58 to 60 are inserted and molded is fixed to the base 51, and lead pins 24, 25, and 28 are connected to respective terminals by welding. A connection part 62 surrounded with a flange 57b of the bracket 57 and the wall surface of the connector 56 is sealed up with a resin 63. Thus, the quality is not degraded, and attachment and building-in for the use are simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a speed sensor for measuring or detecting the running acceleration of an automobile or the like equipped with an internal combustion engine.

BACKGROUND ART FIGS. 5 to 9 show the configuration of a conventional acceleration sensor. In these figures, 1 is a base, and an annular projection 3 having a positioning hole 2 is formed in the center of the surface thereof. 4 is a diaphragm, the center portion of which is fixed to the annular projection 3 of the base 1 by means such as welding. 5 is a piezoelectric ceramic element fixed to the upper surface of the diaphragm 4 for sensor output. As shown in FIG. 10, this piezoelectric ceramic element 5 is formed in a donut shape with a round hole 6 in the center, and the surface is formed into a ring shape with a positive electrode 7 for sensor output and a positive electrode 8 for driving the piezoelectric element. It is divided into two parts.

The piezoelectric ceramic element 5 is conductively bonded to the surface of the diaphragm 4, with the negative electrode 9 on the entire back surface thereof being fitted into the outer periphery of an annular bead 10 formed in the center of the diaphragm 4. ing. Reference numeral 11 denotes a piezoelectric ceramic element for pyroelectric cancellation, and as shown in FIG. It has a positive electrode 13 and a negative electrode 14 on the back surface. The piezoelectric ceramic element 11 is conductively bonded to the back surface of the diaphragm 4 with the positive electrode 13 side on the front surface thereof, with a circular hole 12 fitted in the outer periphery of an annular bead 15 formed at the center thereof.

As shown in FIGS. 12 and 13, the diaphragm 4 has a positioning hole 16 having the same diameter as the positioning hole 2 of the base 1 in the center of the metal disc, and an annular bead concentrically formed around the positioning hole 16. 10
and 15 are formed on the front and back surfaces, respectively, with diameters increasing sequentially. The diaphragm 4 has an upward flange 17 on its periphery, as shown in FIGS. 14 and 15.
It is also possible to increase the output of the acceleration sensor by forming a .

The positive electrode 7 of the piezoelectric ceramic element 5 and the negative electrode 14 of the piezoelectric ceramic 11 are connected to the lead frame 1, respectively.
8.19 with solder 20.21, and is connected to a sensor output lead pin 24 via an insulated embedded lead pin 22 and a circuit board 23. This serves to cancel the charge generated in the positive electrode 7 of the sensor output piezoelectric ceramic 5 due to the pyroelectric phenomenon under the influence of the ambient temperature.

25 is a lead pin for driving the piezoelectric ceramic element;
It is connected to the positive electrode 8 of the piezoelectric ceramic element 5 by solder 27 via a lead frame 26 . 28 is a power supply lead pin of the circuit board 23, and two are ground lead pins, each of which is connected to the circuit board 23. 30 and 31 are insulated embedded lead pins for supporting the circuit board 23. The circuit board 23 is provided with an impedance conversion circuit, an output amplification circuit, a filter circuit, and the like.

22.24.25.28.30.31 of the node pins
is insulated and hermetically fixed to the base 1 by means such as a sealing glass 32, and only the ground pin 29 is electrically connected by means such as brazing. 33 is base 1
This is a sealing glass for sealing the positioning hole 2 of. Power is supplied through a power supply lead pin 28 and a ground pin 29.

34 is a metal cap, and the flange 3 on its periphery
5 is fixed to the base 1 over its entire circumference by means such as resistance welding or cold pressure welding.

Thereby, the space 36 containing the piezoelectric ceramic element 5.6 and the circuit board 23 is sealed.

The acceleration sensor having such a configuration is used by being attached to the body of an automobile or the like using bolts 38 and washers 39 through attachment holes 37 formed on both side ears of the base l.

Next, the operation of the above conventional example will be explained. Acceleration generated by running an automobile or the like is transmitted to the diaphragm 4 via the base 1, causing the diaphragm 4 to bend. Since the deflection of the diaphragm 4 alternately applies tensile force and compressive force to the piezoelectric ceramic elements 5 and 6, charges are generated in the piezoelectric ceramic elements 5 and 6. This charge is converted into a voltage by an impedance conversion circuit on the circuit board 23, and outputted through a filtering circuit and an amplification circuit so as to have a necessary band and optimum output level, and a sensor output is obtained.

Furthermore, since piezoelectric ceramics have a pyroelectric phenomenon that generates electric charges in response to temperature changes, in order to reduce this phenomenon, this acceleration sensor connects piezoelectric ceramic elements 5 and 6 with opposite polarities. The generated charge is canceled out.

In addition, since acceleration sensors used in automobiles and the like require particularly high precision and quality, the positive electrode of the piezoelectric ceramic element 5 is connected to the sensor output so that the controller can check whether the sensor is working reliably. It is divided into two, an electrode 7 and an electrode 8 for driving the element, and by manually inputting an appropriate signal from the transmitting circuit on the controller side to the driving electrode, a corresponding driving output appears on the sensor output electrode 7. It is now possible to diagnose sensor failures.

In this way, the conventional acceleration sensor described above can also measure or detect acceleration in automobiles and the like.

Problems to be Solved by the Invention However, in the conventional acceleration sensor described above, each lead pin 24, 25, 28, 29 is assembled during work.
There was a problem in that a harness had to be connected to each of the parts, making the assembly process extremely troublesome. Also,
There has been a problem in that mounting the acceleration sensor on the body of an automobile is cumbersome.

The present invention solves these conventional problems, and aims to provide an acceleration sensor that is extremely easy to assemble and install during use without degrading the quality of the acceleration sensor. shall be.

Means for Solving the Problems In order to achieve the above object, the present invention fixes a cap and a wiring connector that have mounting bolts to the base of an acceleration sensor to cover the acceleration sensor main body, and Each terminal of the connector and each lead pin of the acceleration sensor main body are connected in advance by means such as welding, and the connection portion is sealed with resin.

Therefore, according to the present invention, the connection between each terminal of the connector and each lead pin of the acceleration sensor main body is sealed with resin, so there is no deterioration in quality, and moreover, the acceleration can be adjusted simply by attaching the connector. Since the connection with the sensor main body is completed, assembly for use is extremely easy. Further, since the cap is provided with a mounting bolt, there is an advantage that the acceleration sensor can be mounted extremely easily.

Embodiment FIG. 1 is a plan view of an acceleration sensor showing an embodiment of the present invention, FIG. 2 is a front view of the same acceleration sensor, and FIG. 3 is a schematic diagram of the inside of the same acceleration sensor with the cap broken away. The plan view and FIG. 4 are side sectional views of the same acceleration sensor. The configuration of the acceleration sensor main body of the acceleration sensor shown in these figures is the same as that of the conventional acceleration sensor described above, except for the base and cap parts, so the same elements are given the same reference numerals and detailed explanations are repeated. Explanation will be omitted.

In FIGS. 1 to 4, 51 is a base, which has an annular projection 3 approximately in the center of its surface. 4 is a diaphragm fixed to the annular protrusion 3 of the base 51, a piezoelectric ceramic element 5 for sensor output is fixed on the front surface of the diaphragm 4, and a piezoelectric ceramic element 11 for pyroelectric cancellation is fixed on the back surface of the diaphragm 4. . The negative electrode on the back surface of the piezoelectric ceramic element 5 is electrically bonded to the surface of the diaphragm 4 , and the positive electrode on the surface of the piezoelectric ceramic element 11 is electrically bonded to the back surface of the diaphragm 4 . The sensor output positive electrode 7 of the piezoelectric ceramic element 5 and the negative electrode of the piezoelectric ceramic 11 are connected to a sensor output lead pin 24 via a lead frame 18, 19 and a circuit board 23, respectively. 25 is a lead pin for driving the piezoelectric ceramic element, and is connected to the element driving positive electrode 8 of the piezoelectric ceramic element 5 via a lead frame 26.

28 is a power supply pin for the circuit board 23;
9 is a lead pin for grounding, and each one is connected to the circuit board 2.
Connected to 3. 30131 is an insulated embedded lead pin for supporting the circuit board 23. 32 and 33 are sealing glasses.

34 is a metal cap, and 7 langes 3 on its periphery
5 is fixed to the surface of the base 51 over the entire circumference.

On the top surface of the cap 34, there is a hexagonal shaft portion 5 that serves as a wrench holder.
A mounting bolt 53 integrally provided with 2 is fixed by welding. Ground lead pin 29 from circuit board 23
Since it is directly brazed to the base 51, it is grounded from the base 51 via the cap 34 and the mounting bolt 53.

Another lead pin 24.2 extending downward from the circuit board 23
A through hole is provided in the base 51 to allow the passage of the 5.28. Metal pipes 54 are fixed in these through holes, and feedthrough capacitors 55 are fitted into the pipes 54 at their outer peripheries, and each lead pin 24, 25, 28 is inserted into the inner periphery. Each is fixed by soldering.

56 is a wiring connector fixed to the base 51.

A bracket 57 and terminals 58, 59, 60 are insert-molded into the resin connector 56.
The connector 56 is fixed to the base 51 by welding the folded portions 57a of both upper ends of the bracket 57 to the back surface of the base 51 as shown in FIG. At this time, the three pipes 54 protruding from the back surface of the base 51 are passed through the insertion holes 61 formed in the bracket 57 for these pipes. Each lead pin 24, 25, 28 is connected to the terminals 58, 60 of the connector 56 by welding, respectively. Finally, the connecting portion 62 surrounded by the flange 57b of the bracket 57 and the wall surface 56a of the connector 56 is sealed with resin 63 to seal and protect the connecting portion 62.

This acceleration sensor is mounted by inserting a mounting bolt 53 into a mounting screw hole in the body of an automobile, etc., applying a spanner to the hexagonal shaft portion 52 and turning it, and screwing the mounting bolt 53 into the mounting screw hole. After that, the connector on the other side of the power source is simply connected to the connector 56 of this acceleration sensor, and the assembly is completed.

The operation of the acceleration sensor main body in the above embodiment is the same as that of the conventional one. That is, the acceleration generated by the running of a car or the like is transmitted to the diaphragm 4 via the base 51.
is transmitted to give flexure to the diaphragm 4. Since the deflection of the diaphragm 4 alternately applies tensile force and compressive force to the piezoelectric ceramic elements 5 and 6, charges are generated in the piezoelectric ceramic elements 5 and 6. This charge is converted into a voltage by an impedance conversion circuit on the circuit board 23, and outputted through a filtering circuit and an amplification circuit so as to have a necessary band and optimum output level, and a sensor output is obtained.

In this way, according to the above embodiment, the mounting bolt and connector are integrated into the acceleration sensor, so that during assembly work, the mounting bolt can be simply screwed into the mating tapped hole. Electrical connection is possible by simply inserting the mating connector into the connector. Furthermore, since the connector block can be attached to the acceleration sensor main body portion afterward, assembly at the time of manufacturing becomes easy and simple. Further, since the connecting portion for sealing the resin is a recessed portion, there are advantages such as the resin does not flow out and the sealing work can be performed easily.

Effects of the Invention As is clear from the above embodiments, the present invention fixes a cap having mounting bolts and a wiring connector to the base of an acceleration sensor, and also fixes each terminal of the connector and each terminal of the acceleration sensor main body. Since the lead pin is connected in advance by means such as welding and the connection part is sealed with resin, it is extremely easy to attach to the mating member without degrading the quality of the acceleration sensor.
Moreover, since the connection with the acceleration sensor is completed simply by attaching the mating connector to the connector, the assembly work for use is extremely simple.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an acceleration sensor according to an embodiment of the present invention, FIG. 2 is a front view of the sensor, FIG. 3 is a schematic plan view of the sensor with its cap cut away to reveal the inside, and FIG. The figure is a side cross-sectional view of the same sensor, Figure 5 is a plan view of a conventional acceleration sensor, Figure 6 is a cross-sectional view taken along the line V-V in Figure 5, and Figure 7 is a cross-sectional view of the sensor.
The figure is a sectional view taken along the line ■-■ in Figure 5, Figure 8 is a plan view of the main parts of the same sensor, Figure 9 is a front sectional view of the main parts of the sensor, and Figure 10 is the main part of the sensor.・
Fig. 11 is a plan view of the piezoelectric ceramic element for pyroelectric cancellation in the same sensor, Fig. 12 is a plan view of the diaphragm in the sensor, and Fig. 13 is shown in Fig. 12. 14 is a plan view showing another example of the diaphragm in the sensor, and FIG. 15 is a sectional view of the diaphragm shown in FIG. 14. DESCRIPTION OF SYMBOLS 1... Base, 2... Positioning hole, 3... Annular projection, 4... Vibration plate, 5... Piezoelectric ceramic element for sensor output, 6... Round hole, 7... Sensor Positive electrode for output, 8... Positive electrode for driving piezoelectric element, 9... Negative electrode, 10... Annular bead, 11... Piezoelectric ceramic element for pyroelectric cancellation, 12... Round hole, 13・・・
-Positive electrode, 14...Negative electrode, 15...Annular bead, 16...Positioning hole, 17...7 lange, 18.19...Lead frame, 20.21...
Solder, 22... Insulated embedded lead pin, 23... Circuit board, 24... Lead pin for sensor output, 25...
・Piezoelectric element drive lead pin, 27...Solder, 28.
...Power supply pin, 29...Ground lead pin, 30, 31...Insulated embedded lead pin, 32
．． 33...Sealed Jj Shirasu 34...Cap, 35
... Frame, 36... Space part, 51... Base,
52...Hexagonal shaft part, 53...Mounting bolt, 54...
・Metal pipe, 55... Feedthrough capacitor, 56...
・Connector, 57... Bracket, 58.59.60
...terminal, 61...insertion hole, 62...connection part, 63...sealing resin. Figure 1 IIPJ5 Figure Vll 11! Is6Figure 7Figure 8Figure 9Figure 10Figure 11Figure 12Figure 13Figure 14Figure 15

Claims (1)

[Claims] A base having an annular projection at the center of its surface, a diaphragm whose center portion is fixed to the annular projection, and two piezoelectric ceramic elements having positive and negative electrodes facing each other and conductively bonded to the front and back surfaces of the diaphragm. a cap having mounting bolts facing outward and fixed to the base so as to cover the piezoelectric ceramic element; and a wiring connector fixed to the base, each terminal of the connector being fixed to the base so as to cover the piezoelectric ceramic element. and each lead terminal of the acceleration sensor main body including the piezoelectric ceramic element, and then the connection portion is sealed with resin.