JPS63295939A - Manometer - Google Patents

Abstract

PURPOSE:To enable the switching of several kinds of unit displays in a manometer by an output signal of a microcomputer, by providing the manometer with externally adjustable variable resistors. CONSTITUTION:A swelled part 16 formed on a base sections 14 of a manometer 10 is fitted into a fluid pipeline, while a screw is inserted through inclined holes 30 and 32 to mount the base section 14 along on a female threaded part. Then, a cover member 12 integrated with first - third printed circuit boards 38-72 or the like is fitted into the base section 14. As a result, a fluid pipeline comes to communicate with a semiconductor pressure sensor 39 and the manometera 10 is fastened on the fluid pipeline. Then, a control 18, namely, a variable resistor RV1 is adjusted from outside to set a desired fluid pressure. To switch pressure unit of the manometer 10, the resistor RV1 is connected to a microcomputer 64 and an voltage value involved in a set angle of the resistor RV1 is judged and processed to switch pressure units continuously. This enables the switching of several kinds of unit displays of the manometer 10.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a pressure needle capable of switching pressure unit display;
More specifically, by connecting a variable resistor to the input terminal of an analog/digital converter (hereinafter referred to as A/D converter) of a one-chip microcomputer, and adjusting the variable resistor, the A/D converter Adjust the voltage input to
The present invention relates to a pressure gauge that is connected to a microcomputer and whose unit display is controlled based on the input voltage, and which enables switching between a plurality of types of units.

[Background of the Invention] Pressure fluid, for example pressurized air, is supplied to an actuator, and a pressure gauge is inserted into the pressure fluid line to check whether the actuator is being driven at a normal pressure. It is generally done in five. in this case,
If abnormally low (or abnormally high) pressure fluid is supplied, it is expected that the actuator itself or the various devices driven by this actuator will be damaged, or that it will cause a dangerous situation for nearby workers. be done. Therefore, various pressure gauges have been developed and used in fluid supply systems.

By the way, the unit of pressure displayed on the pressure gauge is k
g f /cmz is commonly used, but this k
In addition to “gf/c+w”, other units of pressure include Psi,
There are KPa, MPa, bar, etc., and they are selected and used depending on the country or field. In order to accommodate each of these pressure units, manufacturers have conventionally produced several types of pressure gauges individually according to customer requirements.

However, producing different pressure gauges because their units are different in order to detect the pressure of substantially the same fluid results in a small volume of production, which significantly reduces production efficiency. As a result, this causes an increase in manufacturing costs.

Therefore, in order to solve this problem, a pressure gauge has been adopted in which, for example, a switch with one circuit and five contacts is provided on the panel surface of the pressure system so that the pressure unit can be changed by the user. That is, as shown in FIG. 1, each contact is connected to a different input port I0 to 4 of the one-chip microcomputer 2, and each time the five-contact switch 4 is operated, the input port I is changed. ~■4 is the address and the unit displayed on the unit display section 8 in the display 6 is kg f
7cm”, PSI, KPa 5MPa and ba
This is the method of switching to r, etc.

However, in the pressure unit switching method according to this method, the shape of the 1-circuit 5-contact switch is large, so there is the disadvantage that the volume occupied by the pressure gauge (not shown) incorporating it is extremely large. . Moreover, the absolute amount of 1-circuit 5-contact switches on the market is small, so the cost is high.
Furthermore, in order to utilize the five input ports of the one-chip microcomputer 2, the microcomputer 2
There is an inconvenience in that the degree of freedom in setting is severely restricted. In addition, six lead wires are required for one circuit, five-contact switch, including the ground wire, which increases the number of wiring steps and significantly limits the freedom of routing the wires defined on the printed circuit board. This has caused a significant increase in manufacturing costs.

[Object of the Invention] The present invention has been made to overcome the above-mentioned disadvantages. The sliding terminal is connected, and the fixed terminal of this variable resistor is connected to a DC power supply, and by adjusting the variable resistor, the voltage input to the microcomputer is adjusted, thereby controlling the output of this microcomputer. To provide a pressure gauge which is capable of switching the unit display of a pressure gauge among a plurality of types by a signal, is small in size, and has a low manufacturing cost.

[Means for Achieving the Object] In order to achieve the above object, the present invention includes a semiconductor pressure sensor disposed inside a housing, a passage for introducing pressure fluid into the pressure sensor, and The pressure gauge is equipped with a display section that digitally displays the fluid pressure on one side of the housing, and extracts the fluid pressure detected by the pressure sensor as an electrical signal and displays it on the display section, and the pressure gauge is connected to the pressure gauge from the outside. An adjustable variable resistor is provided, a DC voltage is applied between the fixed terminals of the variable resistor, and the voltage output from the sliding terminal is weighted for each pressure unit by adjusting the variable resistor. It is characterized in that it is configured to be divided and digitally displayed on the display unit in a different pressure unit for each voltage division.

[Embodiments] Next, preferred embodiments of the pressure gauge according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, reference numeral 10 designates a pressure gauge according to the invention. This pressure gauge 10 consists of a rectangular cover member 12 and a base portion 14 that is attached to the cover member 12 and screwed onto a fluid conduit (not shown). In this case, the base portion 14
A cylindrical bulge 16 is defined in the cylindrical bulge 16 for introducing pressure fluid into the main body of the second pressure gauge 10 from the fluid conduit.

A pressure setting knob 18 is provided on the front side of the cover part 2.
, a digital display, here a liquid crystal display 20, a pushbutton switch 22 that is pressed to digitally display the set pressure, and fluid being supplied below the set pressure as described later. The light emitting element 24 emits light as an alarm indication when the user selects the unit of pressure PSI, K.
A knob 26 for setting Pa, kg f 7cm'', MPa and bar in desired units is incorporated.

FIG. 3 shows the internal structure of the pressure gauge IO as an exploded perspective view. That is, the bottom surface of the integrally molded base part 14 is provided with an inclined hole part 30.32 for screwing into a female screw part of a fluid conduit (not shown) and fixing the base part 14, and A passage 34 is formed along the axial direction of the bulge 16 into which pressure fluid is introduced. In addition, the base part 1
4 is formed with curved protrusions 36a to 36d for engaging the cover member 12. Reference numeral 38 is a first printed circuit board disposed parallel to the base portion 14, and the first printed circuit board 38 is used for a semiconductor pressure sensor 39 and for amplifying a pressure detection signal related to the pressure sensor 39. Operational amplifier A.

including.

Here, details of the pressure sensor 39 are shown in longitudinal sectional views in FIGS. 4a and 4b. A protrusion 40 is defined in the pressure sensor 39, a passage 42 communicating with the passage 34 defined in the base part 14 is defined in the protrusion 40, and this passage 42 is connected to a pedestal made of glass. It is in communication with a passageway 48 defined in 46 . A sensor chip 50 constituting the pressure sensor 39 is disposed on the upper part of the pedestal 46, and this sensor chip 5
0 is provided with a chamber 52 for surrounding the pressure fluid supplied from the passage 48 (see FIG. 4). A conductive wire 54 is connected to the sensor chip 50, and this conductive wire 54 is electrically connected to a terminal 56. A cover member 58 made of synthetic resin such as polyester is fixed to the open upper end of the pressure sensor 39 to protect the sensor chip 50. Note that the terminal 56 of the pressure sensor 39 is electrically connected to the first printed circuit board 38 for relaying the electrical signal of the pressure sensor 39, as shown in FIG.

A pattern connector 60 defined by a printed pattern is formed at one end of the surface of the first printed circuit board 38 to which the operational amplifier A is attached, and the output signal of the first printed circuit board 38 is transmitted through the pattern connector 60 and the side surface. is connected to the second printed circuit board 6 via a prismatic first connector 62 surrounded on approximately three sides by a flexible printed pattern 61.
A second printed circuit board 66 containing a microcomputer 64 is supplied through a pattern connector (not shown) defined on the back side of the second printed circuit board 66 . In this case, the second printed circuit board 66
A variable resistor RV t for pressure setting, a variable resistor RV for pressure unit setting, and a light emitting diode D+ as an alarm are arranged. A pattern connector 68 is defined above the second printed circuit board 66, and a third printed circuit board 72 is provided with an LCD driver IC (not shown) via the pattern connector 68 and a second prismatic connector 70. connected to. A pattern connector 74 is defined above the third printed circuit board 72, and by connecting the pattern connector 74 to a pattern connector (not shown) defined on the back surface of the liquid crystal display 20, the liquid crystal display 20 It communicates with the sensor 39. Note that the second
A pushbutton switch 22 for displaying the set pressure is arranged above the printed circuit board 66.

Based on such a configuration, the first printed circuit board 38, the second
The printed circuit board 66 , the third printed circuit board 72 , and the liquid crystal display 20 are surrounded by an inner cover member 78 , are integrated, and face the cover member 12 . The pressure unit setting variable resistors Rv! are installed in the holes 18a, 20a, 22a, 24a and 26a defined in the cover member 12, respectively. knob 18, liquid crystal display 20, button switch 22
, a protruding lens member 80 made of plastic or the like disposed on the inner cover member 78, and a pressure setting variable resistor RV.

A knob 26 is attached. In this case, a hook portion 82 with a bent tip is provided around the lower end of the cover member 12.
a to 82d are formed, and the hook portions 82a to 82
d and the pattern protrusions 36a to 36d defined on the base portion 14 are engaged, and the pressure gauge 10 shown in FIG. 2 is assembled.

Next, FIG. 5 shows an electric circuit incorporated in the first to third printed circuit boards 38, 66 and 72, and its structure will be explained.

First, the output side of the bridge circuit B, which is connected to the constant current circuit (2) and includes the equivalent resistance R1 of the pressure sensor 39 related to the sensor chip 50, is connected to the operational amplifier A, and the analog output signal vS of this operational amplifier A+ is sent to the microcomputer 64. will be introduced in In this case, the variable resistor RV3 that constitutes the amplifier circuit related to the operational amplifier AI is the operational amplifier A.

is inserted as a feedback resistor. In addition, variable resistor RV,
is for adjusting the balance point of the resistors constituting the bridge circuit B.

The microcomputer 64 includes a RAM 100° register 102, and in addition to the analog output signal vS as its output signal, a variable resistor RV for setting a desired fluid pressure by adjusting from the outside, and the variable resistor RV. , when the set pressure value displayed on the liquid crystal display 20 reaches the desired value, the R
A button switch 76 to be stored in AM100,
The variable resistor R■2 for switching the pressure unit and the output signal ■S of the operational amplifier A1 are introduced and the output is 0UT.
PUT, an operational amplifier A2 to be closed and taken out to the outside, a transistor TR that becomes conductive when the pressure exceeds the set pressure value, 0UTPUT, which takes out the pressure displayed on the liquid crystal display 20 as a BCD output, and an alarm display. A light emitting diode DI is connected thereto.

The pressure gauge according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, the cylindrical bulge 16 defined on the base portion 14 of the pressure gauge 10 is fitted into a fluid pipe (not shown), and a screw is inserted into the inclined hole 30, 32 to open the fluid pipe. Only the base part 14 is attached to the female screw part formed in the. Next, the cover member 12, in which the first printed circuit board 38 to the third printed circuit board 72, etc. constituting the pressure gauge IO are integrally assembled, is fitted into the base portion 14. As a result, the fluid conduit and the passage 42 of the semiconductor pressure sensor 39 come into communication. In this way, the pressure gauge IO is fixed to the fluid line.

Knob 18 is then used to adjust the pressure switch mechanism;
That is, the desired fluid pressure is set by externally adjusting the variable resistor RV. At the same time, the variable resistor RV is adjusted to set the output of the bridge circuit B to a zero value in advance.

Next, a method for switching the pressure unit of the pressure gauge according to the main part of the present invention will be explained with reference to FIG.

Figure 6a shows the variable resistor RV for pressure unit setting.

This is a unit switching circuit diagram schematically representing the unit setting variable resistor RV, in which one end of the re-fixing terminal is connected to the power supply + and the other end is grounded, and the sliding terminal is connected to the microcomputer 64. Connected to the A/D converter input terminal. In this case, the relationship between the setting angle .theta. of the variable resistor RV and the output voltage (2) is expressed as shown in FIG.

That is, the vertical axis represents the output voltage ■ with respect to the set angle θ on the horizontal axis, and in this case, the set angles θ1 to θ are expressed in pressure units Psi, KPa, kg f/cm", -M, respectively.
to correspond to Pa and bar, and the variable resistor RV
, the output voltage width V, to
0. And R.A.
The output voltage V taken into M100 is compared with a reference voltage written in advance in a ROM (not shown), for example, a voltage having a threshold level at 172 of the output voltage, and the display 20 is displayed according to the corresponding value. Setting unit display 105 is set. That is, the pressure unit can be continuously switched by rotating and adjusting the variable resistor RV.

After such a preparatory step, pressure fluid is introduced into the fluid conduit.
For example, introducing air. As a result, the balance of bridge circuit B is broken, and a differential voltage is generated between its terminals, which is introduced into operational amplifier A. The output signal ■S amplified by the operational amplifier A+ is introduced into the microcomputer 64.

Next, the operation of the control circuit made up of the microcomputer 64 will be explained with reference to the flowchart of FIG.

After initial setting (STP1), input signals are taken in from each port (STP2).

At this time, it is determined whether the button switch 22 is turned on (STP3). When the button switch 22 is turned on, the pressure setting data related to the pressure switch function is numerically displayed on the display 20 (STP4).

On the other hand, when the button switch '22 is OFF, the fluid pressure value data and setting value data are stored in the RAM 100 within the microcomputer 64. That is, the analog output voltage vS of the operational amplifier A is digitized and stored in the RAM 100, while the value set by the variable resistor RV t is also stored in the RAM 100.
(STP5).

In such a state, the pressure value data stored in the RAM 100 is output to the BCD cylinder output terminal (S
TP6). Similarly, the pressure value data is stored in RAM1.
00 and displayed on the display 20 (STP
7). Furthermore, the pressure value data is converted from a digital signal to an analog signal and sent to the operational amplifier A3 at 0UTP.
UT, and is outputted (STP8). Next, after taking in the latch information stored in the memory from the previous cycle (STP9), this output is latched, and it is determined whether it is latched or not. That is, if the output from the alarm terminal 106 is latched, and if the result of this determination is YES, the process moves to a routine that only displays the output value data (STPIO). On the other hand, if it is not latched, the process moves to the next step. In this case, it is determined whether the pressure value data is greater than the set value data (STPII
), when the pressure value data is larger than the set value, the output transistor TR is turned off (STP12). On the other hand, when the pressure value data is smaller than the set value, the pressure value data is smaller than the set value data for a predetermined period of time. To make sure it's small,
The set number of times data is taken out from the RAM 100 and transferred to the register 102 (S T PI3). Then, from the set number of times data, the number of times is decremented by 5TP1.
4) When the pressure reaches 0 (STP15), turn on the output transistor TR (STP16). In this case, an alarm signal is output from the terminal 106 to notify the operator that the pressure value is smaller than the set value. Notify. The output of this alarm signal is latched and stored in memory, allowing the operator to take appropriate actions, such as stopping an actuator (not shown), for example (STP17).

On the other hand, if the pressure value data is greater than the set value, the transistor is turned off and the process returns to step 2.

[Effects of the Invention] As described above, according to the present invention, a variable resistor is connected to a microcomputer in order to switch the pressure unit of a pressure gauge, and the voltage value related to the setting angle of the variable resistor is determined and processed. Accordingly, the pressure unit is continuously switched. Therefore, the unit of the pressure gauge can be easily changed from the outside, for example, by a user. On top of that,
You can easily visually check the display of analog setting values set by turning various knobs and the current pressure value.
Furthermore, it is also possible to digitally display the set values as required. Furthermore, if the current pressure value of the pressure fluid is smaller than this set value, it is also possible to act as a pressure switch, for example, by energizing a relay and stopping the operation of the actuator. Furthermore,
This pressure gauge can integrate a pressure gauge function and a pressure switch function, and can be manufactured in a simple structure and small size. Therefore, the occupied area can be extremely reduced, the space can be used effectively, and the operation can be simplified, and since it is a digital display, the reading error of the pressure gauge itself can be reduced. Various remarkable effects can be obtained.

Although the present invention has been described above by citing preferred embodiments, the present invention is not limited to these embodiments (
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is a conventional pressure unit switching method. FIG. 2 is an explanatory external perspective view of a pressure gauge according to the present invention. FIG. 3 is an exploded perspective view of a pressure gauge according to the present invention. FIGS. 4 a and b is a longitudinal cross-sectional explanatory diagram of a pressure sensor disposed in the pressure gauge shown in Figure 3, Figure 5 is a block diagram of an electric circuit incorporated inside the pressure gauge according to the present invention, and Figure 6a is a diagram shown in Figure 5. Among the electric circuits shown, a schematic explanatory diagram relating to the pressure unit switching circuit, Figure 6 or an explanatory diagram illustrating the operation related to the pressure unit switching circuit shown in Figure 6a, and Figure 7 is the diagram shown in Figure 5. 2 is a flowchart provided for the electric circuit shown in FIG.

Claims (1)

[Claims] (1) A semiconductor pressure sensor is disposed inside a casing, a passage for introducing pressure fluid to the pressure sensor is exposed, and a display section for digitally displaying fluid pressure is provided on one surface of the casing, A pressure gauge that extracts fluid pressure detected by a pressure sensor as an electrical signal and displays it on the display section, the pressure gauge having a variable resistor that can be adjusted from the outside, and a fixed terminal of the variable resistor. By applying a DC voltage between them and adjusting the variable resistor, the voltage output from the sliding terminal is weighted and divided into pressure units, and a digital display is displayed on the display section in different pressure units for each voltage division. A pressure gauge characterized in that it is configured to display.