JPH0425608Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a position detection device, such as a control rack position detection device for an injection pump used to detect the amount of fuel supplied in a diesel engine. The present invention relates to a position detection device.

[Problems to be solved by the prior art and the invention]

Hereinafter, a conventional technique will be described using a position detection device used in an automobile as an example.

In recent years, potential control of automobiles has been actively performed. Electronic control systems using microcomputers are used for various engine controls, clutch controls, gear controls, suspension controls, brake controls, etc. In such a system, engine generated torque and output are essential information for the computer. However, since there are currently few torque sensors that are good for practical use, other information is generally calculated using other information as basic data.

Diesel engine vehicles generally have an injection pump that supplies fuel to the diesel engine body. The amount of fuel that is instantaneously supplied from this injection pump to the diesel engine is important basic data for calculating the engine generated torque and output.

FIG. 2 is a structural diagram of an injection pump A for a diesel engine. A plurality of injection pumps 2 are arranged on the upper part of the camshaft 1, and a pinion 3 attached to each injection pump 2 meshes with one control rack 4. The control rack 4 is connected to an accelerator pedal (not shown) via a link mechanism, a governor mechanism, etc. 5. Therefore, the position of the control rack 4 corresponds to the amount of fuel instantaneously supplied to the diesel engine, and the driver can adjust the engine output by controlling the accelerator pedal.

Therefore, in order to detect the amount of fuel actually being supplied, the position of the control rack 4 has been conventionally detected, and various position detection devices have been developed.

FIG. 2 shows an example of a conventional position detection device, in which a detection device main body 6 consists of a magnetic core 7 and a coil 8. The magnetic core 7 was fixed to the control rack 4 of the injection pump A, and the coil 8 was wound around a primary coil 8a wound around the outer periphery of a cylindrical bobbin 10 and at both ends of the outer periphery of the primary coil 8a. It is composed of a pair of secondary coils 8b. Therefore, the magnetic core 7 and the primary and secondary coils 8a, 8b
A differential transformer is constructed, and the differential voltage generated across the secondary coil 8b indicates the position of the injection control rack.

The detection device main body 6 is fixed to the injection pump A while being housed in a housing 11, and has a primary coil 8a and a secondary coil 8b.
is connected via a lead wire 12 and a connector 13 to a detection circuit section 14 or the like outside the housing 11, for example inside the vehicle interior.

FIG. 4 shows the configuration of the detection circuit section. The detection circuit section includes a temperature compensation circuit 20a and an oscillation circuit 20 that generates an alternating current signal of a constant frequency whose output level changes depending on the detected temperature. A power amplifier circuit 21 that amplifies the power of an AC signal, a differential transformer 22 through which the AC signal amplified by the power amplifier 21 is input to a primary coil, and a differential transformer 22 that changes depending on the position of the magnetic core of the differential transformer. A rectifier circuit 23 that rectifies the output signal of the next coil, a level adjustment circuit 24 that adjusts the level of the DC signal obtained from the rectifier circuit 23, and an output that cuts the level-adjusted DC signal at a predetermined level and outputs it. It consists of a limiter circuit 25.

Incidentally, in the above-mentioned position detection device, the detection device body 6 itself has temperature dependence of its output, and the detection circuit section 14 also has temperature dependence as a single circuit. Conventionally, temperature compensation for these has been performed by providing a compensation circuit within the detection circuit section 14, and this compensation circuit compensating for the temperature dependence of the detection device main body 6 and the detection circuit section 14 as a whole.

However, with this method, good temperature compensation is possible if the detection device main body 6 and the detection circuit section 14 are at the same temperature, but as shown in FIG. Furthermore, when the detection circuit sections 14 are installed in each vehicle interior, it is difficult to perform sufficient temperature compensation because there is a significant difference in the temperature environments.

In addition, since the detection device main body 6 and the detection circuit section 14 are separate bodies, there is a possibility of noise generation or conduction failure in the lead wire 12, connector 13, etc. that connect the two, and space efficiency is also improved. do not have.

The present invention has been made in view of the above points, and aims to provide a position detection device that is easy to compensate for temperature and is space efficient.

[Means for solving problems]

In order to achieve the above object, the present invention includes a magnetic core that is interlocked with a displacement member, a coil that is wound around a bobbin and outputs an electric signal according to the position of the magnetic core, and a magnetic core that is generated by the electric signal obtained from the coil. A position detection device comprising a detection circuit section that extracts a displacement signal according to the position of the core, wherein the bobbin is formed of a ceramic material and the electronic components of the detection circuit section are attached using the bobbin as an insulating substrate. It is characterized by This allows the detection circuit section to be placed in a temperature environment substantially similar to that of the main body of the detection device consisting of the magnetic core and coil, and allows the electronic components of the detection circuit section to be directly mounted on the bobbin.

〔Example〕

FIG. 1 is a sectional view of the detection device main body 6 in the embodiment.

The structure and operation of the magnetic coil and the coil 8 are the same as those of the conventional example explained in FIG. 3, so the explanation thereof will be omitted by giving the same reference numerals.

In FIG. 1, a bobbin 10 having flanges 10a at both ends is fixed in a cylindrical housing 11, and a magnetic core 7 is inserted into a center hole 10b of the bobbin 10. Both flanges 10a
A coil 8 is wound around the outer periphery of the bobbin 10 between the two, and an electronic component 14a consisting of, for example, a chip component tube constituting the detection circuit section 14 is fixed onto the surface of one flange 10a.

The bobbin 10 is integrally formed of a high-resistance, non-magnetic ceramic material, and is preferably the same material that is generally used for hybrid IC substrates. The detection circuit section 14
The electronic component 14a is directly fixed to the flange 10a surface of the bobbin 10 on which a conductive pattern is printed to form a hybrid IC, and the whole is integrated with a resin mold B.

A substrate 16 is attached within the housing 11 at a distance from this molded portion, and this substrate 1
A variable resistor 15 is fixed on 6. The variable resistor is used to adjust the output level of the detection circuit 14, and enables zero adjustment and gain adjustment.

The injection pump A, which is placed near the diesel engine, is in a temperature environment that changes rapidly depending on the temperature outside the vehicle, the temperature of the engine body, etc. The heated bobbin 10 is also under similar temperature conditions. Therefore, the temperature dependence of the position detection device main body 6 consisting of the coil 8 and the magnetic core 7 is high;
This is compensated for by a compensation circuit provided within the detection circuit section 14. At this time, since the electronic component 14a of the detection circuit section 14 is directly attached to the bobbin 10, its temperature dependence can be handled together with the temperature dependence of the detection device main body 6.

[Effect of idea]

The present invention is as described above, and the detection circuit section is directly fixed on the ceramic bobbin. Therefore, the main body of the position detection device and the detection circuit section can be placed under almost the same temperature environment, and the temperature compensation circuit in the detection circuit section can easily and accurately compensate the temperature of the entire position detection device. . Furthermore, since the bobbin is made of ceramic material, the electronic component elements constituting the detection circuit can be mounted directly on the bobbin, and the number of parts can be reduced without requiring a special circuit board.

In addition, since there is no need to connect the detection device main body and the detection circuit with long lead wires or connectors, it is possible to prevent noise generation and connection failures, and to save space by making the entire device into a unit. It can be made advantageous.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the main structure of an embodiment of the present invention, Fig. 2 is a schematic structure diagram of an injection pump for a diesel engine, and Fig. 3 is a sectional view showing the main structure of a conventional position detection device. , FIG. 4 is a circuit diagram showing an example of the circuit of the detection circuit section. 4... Control rack, 6... Position detection device body, 7... Magnetic core, 8... Coil, 10...
...Bobbin, 10a...Bobbin flange, 14...
...Detection circuit section.

Claims (1)

[Claims for Utility Model Registration] (1) A magnetic core interlocked with a displacement member, a coil wound around a bobbin that outputs an electric signal according to the position of the magnetic core, and a magnetic core that is generated by the electric signal obtained from the coil. In the position detection device, the bobbin is formed of a ceramic material, and the electronic components of the detection circuit are mounted using the bobbin as an insulating substrate. A position detection device characterized by: (2) The position detection device according to claim 1, wherein the electronic components of the detection circuit section are attached using the flange surface of the bobbin. (3) The detection circuit section is a hybrid structure in which electronic components are attached using the flange surface of the bobbin.
A position detection device according to claim 1 of the utility model registration claim, characterized in that it has an IC configuration. (4) The position detection device according to claim 1 or 2, wherein the displacement member is a control rack for an injection pump that supplies fuel to an engine.