JPH0239727B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automobile sensor for detecting pressure such as a hydraulic pressure gauge.

Conventionally, in a sensor installed in a car, for example, a hydraulic pressure sensor, when the hydraulic pressure to be sensed rises, engine oil enters from the pressure introduction path 2 of the case 1 of the hydraulic sensor, as shown in FIG.
When the diaphragm, which is the part to be sensed by the oil pressure sensor, is pushed up against the spring force of the coil spring 3, the push pin 5 erected on the upper surface of the diaphragm 4 is pushed up.
rises in synchrony with the movement, pushes up one side of the base 15 to which the movable terminals 6 and 7 are attached, rotates the movable terminals 6 and 7 counterclockwise, changes the resistance of the variable resistor 8, and adjusts the hydraulic pressure gauge. 9 is moved in proportion to the oil pressure, and when the oil pressure is low, the movable terminals 6 and 7 are rotated clockwise by a return spring (not shown) attached to one end of the base 15. and one movable terminal 7 is connected to a contact 1 provided at the right end of a sliding plate 11 on which the movable terminal 7 slides.
2, and was configured to light up an alarm lamp (warning lamp) 13. 14 is an ignition key.

However, with this conventional structure, it is difficult to improve the accuracy of the sensor itself and the accuracy of the oil pressure gauge. Or, when the engine is idling and the oil pressure is low (usually the oil pressure value at idling is 0.3 to 1 kg/ ^cm2 ), the oil pressure gauge needle points to 0 and the oil pressure is generated. There was a risk that he might pretend that he had not done so. Furthermore, even if the pointer can be set accurately, the sensor's resistance to changes in oil pressure will change smoothly, and there will be little change in the position of the pointer when the oil pressure is low and when there is no oil pressure, and there will be almost no difference. Therefore, it was difficult to read the difference with an oil pressure gauge.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to:
In an automotive sensor that changes the current by changing the resistance of a variable resistor, the resistance of the sensor changes rapidly around a specified value in response to changes in the pressure of the object to be sensed. This makes it possible to clearly identify whether or not the pressure is appropriate by making a large difference in the deflection of the needle, which is one of the display means of the pressure gauge of the object to be sensed. In order to display the displacement of the pressure of the object to be sensed, a display device is provided having a series of scales including a specified pressure value and a pointer indicating a position on the scale corresponding to the pressure, and a sensing circuit for moving the pointer is provided. , the indicator has a movable terminal that moves in response to the displacement of the pressure of the object to be sensed, and a variable resistor whose resistance value decreases as the pressure increases due to the movement of the movable terminal. A series connection circuit consisting of a fixed resistor and a switch is connected in parallel with the variable resistor between the variable resistor and the display, and the switch is connected in series with the variable resistor and the display. It consists of a movable terminal for a fixed resistance circuit that moves and an electrode plate on which the movable terminal for a fixed resistance circuit comes into contact with and separates from it, and the movable terminal for a fixed resistance circuit separates from the electrode plate when the pressure of the object to be sensed is below a specified value, and the series connection is performed. The circuit is opened to form a series resistance circuit using the variable resistor, and when the pressure exceeds this specified value, the movable terminal for the fixed resistance circuit comes into contact with the electrode plate, closing the series connection circuit and connecting the variable resistor and the fixed resistance circuit. By configuring the changeover switch to form a parallel resistance circuit with a resistor, a fixed resistance circuit is opened when the pressure displacement of the object to be sensed is below a specified value, and the display shows the following:
It is displayed according to the value of only the variable resistor, the fixed resistance circuit is closed at high pressure exceeding the specified value, and the display is displayed according to the value of the parallel resistance of the variable resistor and the fixed resistor. Therefore, at a specified value of the displacement of the pressure of the object to be sensed, the resistance of the circuit changes from resistance to series resistance and increases (the current decreases), and at high pressure exceeding the specified value, the resistance of the circuit changes from series resistance to parallel resistance. Even when the pressure changes and becomes smaller (the current increases) and the pointer reaches a slightly higher pressure than the specified value, the pressure will be higher than the position (scale) engraved on the display that corresponds to the specified value on the series of scales. It acts so that it swings largely toward the pressure side. As a result, the pointer of the pressure gauge does not swing when the specified value is exceeded, but when the specified value is exceeded, the pointer swings greatly, so that the pressure of the object being sensed is at the specified value and when it exceeds the specified value. In addition to being able to clearly distinguish and know
As the pressure increases from a value that is slightly higher than the specified pressure, the resistance value of the variable resistor decreases further while the parallel resistance remains as described above, so the resistance value of the circuit also decreases. The pointer moves from the position corresponding to the pressure slightly higher than the resistance value to the position on the higher pressure side,
It is an object of the present invention to provide a sensor for an automobile that can be made to be unmistakable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments in which the present invention is applied to a hydraulic pressure gauge will be described.

a is the displacement of the object to be sensed, such as hydraulic pressure;
In other words, an oil pressure sensor that detects the level of oil pressure, 21
is the case of the oil pressure sensor a, and the case 2
Below 1, on the outer periphery, there is an engine oil circulation path 4.
A cylindrical pressure introduction path 22 having a screw portion 43 that is screwed into the screw hole 42 of No. 1 is formed, and by screwing the pressure introduction path 22 into the screw hole 42, the oil pressure sensor a and the engine oil circulation are connected. A passage 41 is communicated with the case 21 so that engine oil flows into the case 21. Also, case 2
1 includes a diaphragm 24 serving as a sensing object and having a push pin 23 erected on its upper surface; and the diaphragm 24.
4, a bracket 30 fixed to the case 21, a base plate 29 rotatably supported by the bracket 30, and a partition plate 28 erected in the center of the base plate 29. , variable resistance movable terminals 2 erected on both sides of the board 29
6, a fixed resistance circuit movable terminal 27 that moves in response to the displacement of the pressure of the object to be sensed, and a variable resistance circuit movable terminal 27 that is fixed to the case 21 so that the variable resistance movable terminal 26 can slide in contact with it. Made variable resistor 3
2 and a sliding plate 33 on which a movable terminal 27 for a fixed resistance circuit can contact and slide, and the board 29 is moved backward by a return spring 31 attached to the rear end of the board 29. It is biased to tilt to the right (in the drawing), and when the oil pressure increases, it is pushed up by the push pin 23, rotates counterclockwise, and tilts forward (to the left in the drawing). .

Reference numeral 37 is a hydraulic pressure gauge which is a display device, and the display panel 37 is provided with a display board on which a series of scales including a specified value (hydraulic pressure is 0 kg/cm ² ), which will be described later, is engraved. A pointer is provided to indicate the position (scale) on the scale according to the displacement of the hydraulic pressure. And this display 37
The sensing circuit that moves the pointer is configured as follows.

On the sliding plate 33, there is an electrode plate 36 that becomes a conductor that the tip of the fixed resistance circuit movable terminal 27 comes into contact with and separates from.
The tip of the fixed resistance circuit movable terminal 27 is fixed and extends in the front-rear direction along the moving direction, and the electrode plate 36 and the fixed resistance circuit movable terminal 27 constitute a switch. A series connection circuit, which will be described later, is opened to form a series resistance circuit using the variable resistor, and when the pressure exceeds this specified value, the movable terminal for the fixed resistance circuit comes into contact with the electrode plate, closing the series connection circuit and forming the series resistance circuit using the variable resistor. A changeover switch is provided to form a parallel resistance circuit including a resistor and the fixed resistor.

A terminal 35 for a warning lamp 34 is fixed to the rear of the electrode plate 36 at an appropriate distance from the electrode plate 36. Moreover, the variable resistor 32 is
Resistance wires 45 such as thin nichrome wires are connected to a substrate 44 made of an insulator that extends in the front-rear direction along the moving direction of the tip of the movable terminal 26 of the variable resistor so that the resistance wires 45 do not touch each other. The resistance wire 45 is arranged such that the contact portion with the tip of the movable terminal 26 of the variable resistance is electrically connected to the movable terminal 26 of the variable resistance. Along with the change, the resistance value between the front end of the variable resistor 32 and the tip of the movable terminal 26 of the variable resistor changes. A variable resistor 32 whose resistance value decreases as the pressure increases due to the movement of the substrate 29.
It is becoming. Reference numeral 40 denotes a ground, and both the movable terminals 26 and 27 are grounded through the board 29, the bracket 30, and the case 21.

A fixed resistor 38 having one end connected to the front end of the electrode plate 36 is provided in a circuit connecting the oil pressure gauge 37 and the sliding plate 33 to form a series connection circuit, and is connected in parallel with the variable resistor 32. It is made to become. 39 is an ignition key, one end of which is connected to a battery 46, and the other end is connected via a fuse 47 so that the warning lamp 34 and oil pressure gauge 37 are connected in parallel. There is.

The tip of the movable terminal 26 of the variable resistor is the variable resistor 32
When the contact position moves to the right side, the resistance of the variable resistor 32 is large and the circuit current flowing to the oil pressure gauge 37 is small, indicating that the oil pressure of the oil pressure gauge 37 is low.When the contact position moves to the left side, the resistance of the variable resistor 32 becomes small. , oil pressure gauge 3
The circuit current flowing through the oil pressure gauge 37 increases, and the pointer of the oil pressure gauge 37 indicates that the oil pressure is high.

Note that the pointer of the oil pressure gauge 37 is set to accurately indicate 0 kg/cm ² on the scale when the oil pressure is the specified value of 0 kg/cm ² , taking into account the accuracy of the oil pressure gauge 37. ² , the pointer will show the scale 0Kg/cm ² even if the dispersion of the pointer value is maximum on the positive side.In other words, when the oil pressure is 0Kg/ ^cm2 , the pointer will generally be more negative than the scale 0Kg/ ^cm2 . If the oil pressure increases slightly and exceeds the specified value with the pressure side indicated,
The fixed resistance circuit movable terminal 27 is separated from the terminal 35 and comes into contact with the electrode plate 36, and the oil pressure gauge 37 is set so that the pointer of the oil pressure gauge 37 can swing greatly toward the positive pressure side beyond the scale of 0 kg/cm ² . To prevent the pointer from swinging below the scale 0Kg/ ^cm2 , set the scale 0Kg/ ^cm2.
Provide a pointer stopper at the position. Thereby, even if the accuracy of the oil pressure gauge 37 is the same as before, the oil pressure gauge 37 can be made to indicate the oil pressure of 0 kg/cm ² .

With the above configuration, when the hydraulic pressure is low, the board 29 is tilted rearward, and both the movable terminals 26, 2
7 to the rear side, and move the fixed resistance circuit movable terminal 2.
7 is brought into contact with the terminal 35 of the warning lamp 34 to light up the warning lamp 34. However, when the pressure increases, the engine oil entering from the pressure introduction path 22 pushes up the diaphragm 24, and as a result, the board 29 is pushed up by the push pin. 23 and rotates forward, both the movable terminals 26, 2
7 also rotates forward. As a result, the fixed resistance circuit movable terminal 27 is separated from the terminal 35, and the electrode plate 36 is separated from the terminal 35.
come into contact with.

Here, assuming that the resistance value of the variable resistor 32 is Rv and the resistance value of the fixed resistor 38 is Rc, the circuit resistance R between the oil pressure gauge 37 and the earth 40 is the contact between the fixed resistance circuit movable terminal 27 and the terminal 35. When the warning lamp 34 is turned on,
It is equal to the resistance value Rv of the variable resistor 32, R=Rv, and when the fixed resistance circuit movable terminal 27 is separated from the terminal 35 and is in contact with the electrode plate 36, R=
1/(1/Rv+1/Rc), the circuit resistance R
The larger the resistance value Rv of the variable resistor 32 is, the more the ratio is influenced by the resistance value Rc of the fixed resistor 38.

Therefore, when the oil pressure V is high and the resistance value Rv is small, the effect of adding the fixed resistor 38 is small;
When the oil pressure V is low and the resistance value Rv is large, the effect of adding the fixed resistor 38 is large.

Therefore, when the terminal 35 leaves the terminal 35 and begins to come into contact with the electrode plate 36, the circuit resistance between the oil pressure gauge 37 and the ground 40 suddenly decreases, the circuit current i flowing to the oil pressure gauge 37 suddenly increases, and the oil pressure gauge 37 The pointer can be made to swing significantly, and therefore the increase in the oil pressure V can be clearly known. Furthermore, when the oil pressure V further increases, the influence of the resistance value Rc becomes smaller, and the pointer of the oil pressure gauge 37 begins to swing approximately in proportion to the resistance value Rv.

Incidentally, as a method of making the low-pressure side swing largely, there was a method of using a conical spring as the spring 25 that presses the diaphragm 24, but in this case, the scales on the high-pressure side would be close to each other, as shown in Fig. 6C. Therefore, it is undesirable. In this regard, according to the present invention,
This does not occur because the scale of the oil pressure gauge 37 can be set at approximately equal intervals as shown in FIG. 6B, similar to the conventional one (see FIG. 6A).
Further, in the above embodiment, the terminal 35 of the warning lamp 34 and the electrode plate 36 are cut off by leaving a space between them, but the resistance may be increased at that portion.

FIG. 7 shows the hydraulic pressure V generated in the pressure introduction path 22,
This is a graph comparing the circuit current i flowing through the oil pressure gauge 38 in the case of the present invention and the conventional case, where the solid line a represents the circuit current i in the case of the present invention, and the dotted line b represents the circuit current i in the case of the present invention. The ruled line portion represents the portion affected by the fixed resistor 38 when the fixed resistor Rc is made larger than the variable resistor Rv. c represents the circuit current i in the case of the conical spring method.

As described above, according to the present invention, in order to display the displacement of the pressure of the object to be sensed (hydraulic pressure in the embodiment), a series of scales including a specified value of pressure and a position on the scale corresponding to the pressure are indicated. a sensing circuit for moving the pointer;
The indicator has a movable terminal that moves in response to the displacement of the pressure of the object to be sensed, and a variable resistor whose resistance value decreases as the pressure increases due to the movement of the movable terminal. connect in series,
Between this variable resistor and the display, a series connection circuit of a fixed resistor and a switch is connected in parallel with the variable resistor.
This switch consists of a movable terminal for a fixed resistance circuit that moves in response to the displacement of the pressure of the object to be sensed, and an electrode plate on which the movable terminal for the fixed resistance circuit comes into contact with and separates from it.
When the pressure of the object to be sensed is below a specified value, the movable terminal for the fixed resistance circuit separates from the electrode plate to open the series connection circuit, forming a series resistance circuit using the variable resistor;
At a high pressure exceeding this specified value, the movable terminal for the fixed resistance circuit comes into contact with the electrode plate, closing the series connection circuit and creating a parallel resistance circuit of the variable resistor and the fixed resistor. ,for example,
When used as an oil pressure gauge, which is an oil pressure sensor, when there is no pressure such as oil pressure generated and the pressure is 0 kg/cm ² , the pointer of the pressure gauge will accurately point to 0 kg/cm ² . Even if the pressure increases slightly, the needle remains at 0.
Set the pointer at a sufficient distance from Kg/cm ² .

Further, according to the present invention, when the fixed resistance circuit is opened, the switch closes an alarm circuit such as a warning lamp provided in parallel with the fixed resistance circuit, so that the fixed resistance circuit and the alarm circuit are closed. Since it is formed with a changeover switch that switches between the two modes, when the lamp goes out, the needle swings significantly, clearly indicating that the pressure has increased. Therefore, the driver can easily confirm that the pressure of the object to be sensed has increased.

[Brief explanation of drawings]

Fig. 1 is a side sectional view showing a conventional oil pressure sensor, Fig. 2 is a circuit diagram of the same as above, Fig. 3 is a side sectional view showing an oil pressure sensor according to the present invention, and Fig. 4 is an enlarged view of the main parts of the same. , Fig. 5 is the same circuit diagram as above, Fig. 6 A, B, and C are comparison diagrams showing the scale status of the oil pressure gauge according to the present invention and the display board of the conventional product, and Fig. 7 shows the generated oil pressure and the oil pressure gauge. FIG. 2 is a graph diagram comparing the relationship between the present invention and the conventional one, showing the relationship with the circuit current. a is an oil pressure sensor, 26 is a variable resistance movable terminal,
27 is a movable terminal for a fixed resistance circuit, 32 is a variable resistor, 36 is an electrode plate, and 38 is a fixed resistor.

Claims (1)

[Claims] 1. In order to display the displacement of the pressure of the object to be sensed, a display device is provided which has a series of scales including predetermined pressure values and a pointer indicating the position on the scale corresponding to the pressure. The sensing circuit that moves the pointer has a movable terminal that moves in response to the displacement of the pressure of the object to be sensed, and as the pressure increases due to the movement of this movable terminal, the resistance value decreases. A variable resistor that changes as follows is connected in series with the display device, and a series connection circuit of a fixed resistor and a switch is connected in parallel with the variable resistor between the variable resistor and the display device. It consists of a movable terminal for a fixed resistance circuit that moves in response to the displacement of the pressure of the target object, and an electrode plate that connects and separates the movable terminal for the fixed resistance circuit. The movable terminal separates from the electrode plate to open the series connection circuit, forming a series resistance circuit using the variable resistor, and at a high pressure exceeding this specified value, the movable terminal for the fixed resistance circuit comes into contact with the electrode plate, opening the series connection circuit. A sensor for an automobile, characterized in that it is provided in a changeover switch that is closed to form a parallel resistance circuit of the variable resistor and the fixed resistor. 2. The switch is configured to close an alarm circuit such as a warning lamp installed in parallel with the fixed resistance circuit when the fixed resistance circuit is opened, thereby switching between the fixed resistance circuit and the alarm circuit. The automotive sensor according to claim 1, characterized in that it is formed of a changeover switch. 3. The switch has a fixed resistance circuit movable terminal that moves on a conductor connected to a fixed resistance, and the fixed resistance circuit movable terminal moves in response to the displacement of the pressure of the object to be sensed. The movable terminal for the fixed resistance circuit is provided separately from the movable terminal of the variable resistor that moves, and is configured to interlock with the movable terminal of the variable resistor, and is automatically fixed when the movable terminal for the fixed resistance circuit is detached from the conductor. The automotive sensor according to claim 1, characterized in that the resistor circuit is configured to be open.