Measuring and testing – Fluid pressure gauge – U-tube liquid column
Reexamination Certificate
2000-01-18
2001-10-23
Oen, William (Department: 2855)
Measuring and testing
Fluid pressure gauge
U-tube liquid column
Reexamination Certificate
active
06305228
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressure sensor device and a suction release apparatus, and more particularly to a pressure sensor device which is provided in a pressure generating apparatus for setting the inside of a pressure tube in a negative pressure with a negative pressure-generating valve for generating the negative pressure, and setting the inside of a pressure tube to a positive pressure with a positive pressure-generating valve for generating the positive pressure, the pressure sensor device being provided for detecting the pressure inside the pressure tube.
2. Description of the Related Art
Conventionally, there is proposed a pressure generating system for suctioning work by placing the interior of a pressure tube connected to a work in a negative pressure state (a vacuum state but not a complete vacuum state). Note that the pressure generating apparatus is provided with a pressure sensor device for detecting the pressure (either positive pressure or negative pressure) inside a pressure tube and displaying the pressure detected inside the pressure tube.
In the above pressure generating system, the vacuum generating electro-magnetic valve is opened to place the interior of the pressure tube in a negative pressure state. Namely, the pressure generating system allows compressed air supplied from a compressor (on the primary side) to flow into a diffuser by opening the vacuum generating electro-magnetic valve. Along with this, the interior of the pressure tube is placed in a negative pressure state by cawing the air in the pressure tube (on the secondary side) to flow into the diffuser.
Further, in this pressure generating system, in order to place the interior of the pressure tube in a positive pressure state, the vacuum generating electro-magnetic valve is closed and a vacuum release electro-magnetic valve is opened. Namely, in this pressure generating system, by closing the vacuum generating electro-magnetic valve and opening the vacuum release electro-magnetic valve, compressed air supplied from the compressor (primary side) can be prevented from flowing into the diffuser and can be made to flow into the pressure tube, thereby placing the interior of the pressure tube in a positive pressure state. Note that the term “breakdown” is used because compressed air is made to flow into the interior of the pressure tube thereby breaking down the state of vacuum which had existed in the pressure tube.
However, a sequencer located outside the pressure generating apparatus directly controls the vacuum generating electro-magnetic valve and the vacuum release electro-magnetic valve with the result that a control load of the sequencer is large. In particular, when various types of control have to be performed on the vacuum generating electro-magnetic valve and the vacuum release electro-magnetic valve because of the type of work (the weight and the state of the suction surface), because the sequencer has to perform each of the controls, the control load becomes increasingly larger.
Furthermore, when the pressure sensor device detects the pressure in the pressure tube and the detected positive pressure is a threshold value or greater, a positive pressure state signal is output via a first signal line. On the other hand, when the detected negative pressure is a threshold value or greater, the negative pressure state signal is output via a second signal line. In other words, two signal lines are required to output the pressure (positive pressure and negative pressure) state in the pressure tube.
SUMMARY OF THE INVENTION
The present invention has been made in view of the aforementioned fact, and an object of the present invention is to provide a pressure sensor device which reduces the external control load, and which is capable of reducing to one line the number of signal lines for outputting the state of the pressure inside a pressure tube.
In order to attain the above object, the pressure sensor device according to the first aspect of the present invention is provided in a pressure generating apparatus. The pressure generating apparatus places the interior of a pressure tube in a negative pressure state using a negative pressure-generating valve for generating negative pressure, and places the interior of the pressure tube in a positive pressure state using a positive pressure-generating valve for generating positive pressure. The pressure sensor device detects both positive pressure and negative pressure in the pressure tube.
Input device inputs an instruction signal. In the input instruction signal, a first state change-over from one of a high state having a relatively large value or a low state having a relatively small value to the other of the high state having a relatively large value or the low state having a relatively small value represents an instruction to generate negative pressure, while a second state change-over from the other of the high state having a relatively large value or the low state having a relatively small value to the one of the high state having a relatively large value or the low state having a relatively small value represents an instruction to generate positive pressure. The instruction signal is selectively changeable from a high state to a low state and vice-versa. A change of the instruction signal from one state to the other state is an instruction to generate negative pressure, and a converse change of the instruction signal is an instruction to generate positive pressure.
A control device thus controls the negative pressure-generating valve and the positive pressure-generating valve on the basis of the first state change-over and the second state change-over in an instruction signal input by the input device.
In this manner, since the pressure sensor device controls the negative pressure-generating valve and the positive pressure-generating valve on the basis of the first state change-over and the second state change-over in the instruction signal, the control load of an external device such as a sequencer or the like can be reduced.
Here, the control device may control the negative pressure-generating valve and the positive pressure-generating valve in accordance with an operation mode selected from a plurality of operation modes. In this manner, since the control device of the pressure sensor device controls the negative pressure-generating valve and the positive pressure-generating valve in accordance with the operation mode selected from the plurality of the operation modes, the control load of an external device such as a sequencer or the like can be further reduced.
Furthermore, the control device may open the negative pressure-generating valve on the basis of the first state change-over and may close the negative pressure-generating valve after a predetermined time has passed before the second state change-over and since the value of the negative pressure generated in the pressure tube by the opening of the negative pressure generating valve has reached the threshold value on the negative pressure side or more.
Note that at least one of the above threshold value and the predetermined time may be able to be set.
Furthermore, the control device may open the positive pressure-generating valve when a predetermined delay time has passed after the completion of the second state change-over. Furthermore, the control device may open the positive pressure-generating valve on the basis of the second state change-over. When the value of the positive pressure generated in the pressure tube by the opening of the positive pressure-generating valve has reached the threshold value or more on the positive pressure side, the positive pressure-generating valve may be closed.
A pressure sensor device according to a second aspect of the present invention is provided in a pressure generating apparatus for placing the interior of a pressure tube in a negative pressure state using a negative pressure-generating valve for generating negative pressure and for placing the interior of the pressure tube in
Kagaya Kouki
Kimura Masahito
Sato Yutaka
Knobbe Martens Olson & Bear LLP
Myotoku Co., Ltd.
Oen William
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