JPH031060A - Pressure sensor for air conditioner - Google Patents

Abstract

PURPOSE:To minimize the fluctuation range of pressure being controlled, prevent abnormal rise in evaporation temperature of the refrigerant gas, and improve the efficiency of a compressor by a method wherein the displacement of a bellows is continuously converted to electric signals by a differential transformer, the electric signals are compared with an electric signal equivalent to the preset pressure value to control the rotating speed of the compressor. CONSTITUTION:When the inside pressure of a pipe 1 becomes higher than the atmo spheric pressure due to the refrigerant gas in the pipe, a bellows 2 extends and a magnetic core 7 is transferred into a central part of a differential transformer 8. The differential transformer 8 excites an exciting coil by an exciting circuit 91, and rectifies outputs of a detecting coil by a rectifying circuit 92 to submit the output signals. The transfer amount of the magnetic core 7 is determined by the spring constants of a bias spring 5 and the bellows 2, and the pressure P of refrigerant gas in the pipe 1. Therefore, the rectifying circuit 92 outputs the output signals in propor tion to the pressure P of the refrigerant in the pipe 1. Next, outputs of a pressure sensor 20 of an air conditioner are compared with outputs of a pressure setter 21 by a comparator 22, and the deviation signals are input to an inverter controller 23 so as to control the rotating speed of a refrigerating compressor 24.

Description

DETAILED DESCRIPTION OF THE INVENTION A.Objective of the invention [Industrial application field] The present invention continuously changes the rotational speed of a refrigeration compressor using an inverter device, thereby making it possible to steplessly control the cooling and heating capacity. The present invention relates to a pressure sensor for an air conditioner that outputs a signal of refrigerant gas pressure to a control device of the air conditioner.

[Conventional technology]

Conventionally, a pressure sensor used in an inverter control device of an air conditioner mechanically operates a micro switch 66 by displacement according to the refrigerant gas pressure inside a pipe 61, as shown in FIG. It has a structure that outputs and detects pressure, and includes a pressure sensor 41 for detecting upper limit pressure and a pressure sensor 42 for detecting lower limit pressure shown in FIG.
The signal is input to the inverter control device 43 to control the rotation speed of the refrigeration compressor 44. However, when controlling the rotation speed of a refrigeration compressor using such a pressure sensor, there are problems described below.

In the above pressure sensor, the upper limit setting pressure PH is set by the upper limit pressure detection pressure sensor 41, the lower limit setting pressure Pt is set by the lower limit pressure detection pressure sensor 42,
is set to have a predetermined pressure difference PD. Therefore, the controlled pressure P changes within a range PK that slightly exceeds the pressure difference PD, as shown by the dashed line in FIG. If this state exceeds the upper limit set pressure Po, it will cause adverse effects such as an abnormal rise in the evaporation temperature of the refrigerant gas, while if the operating time increases below the lower limit set pressure Pt, the efficiency of the refrigeration compressor will worsen. There was a problem with letting them do it.

[Problem to be solved by the invention]

The present invention continuously converts the value of the controlled pressure P input to the inverter control device that controls the rotation speed of the refrigeration compressor into an electric signal, reduces the range of change in the controlled pressure P, and reduces the evaporation of refrigerant gas. An object of the present invention is to provide a pressure sensor for an air conditioner that prevents an abnormal rise in temperature and improves the efficiency of a compressor.

Margin 1: Configuration of the Invention [Means for Solving the Problems] The present invention provides an inverter-type air conditioner that changes the rotational speed of a refrigeration compressor using an inverter device. Installed on the low pressure side or high pressure side of the compressor, or on both the low pressure side and high pressure side piping,
It has a displacement part that generates displacement according to the refrigerant gas pressure inside the piping, a magnetic core is attached to this displacement part, the displacement of this magnetic core is detected by a differential transformer, and it is continuously converted into an electrical signal. The pressure sensor for an air conditioner operates to control the rotation speed of the compressor by comparing the electric signal with an electric signal corresponding to a preset pressure setting value.

That is, the present invention provides a pressure sensor for an air conditioner that detects refrigerant gas pressure for controlling the rotation speed of a refrigeration compressor using an inverter device. A magnetic core is attached to the tip of the bellows, a coil is attached to the frame opposite to the frame on which the bellows is attached, and in combination with the magnetic core, a differential transformer is constructed, and the displacement of the bellows is controlled by the differential transformer. Continuously converts into electrical signals,
A pressure sensor for an air conditioner is characterized in that the electrical signal is compared with an electrical signal corresponding to a preset pressure value to control the rotation speed of the refrigeration compressor.

[Effect]

An airtight bellows is connected to the piping of the air conditioner and expands and contracts due to internal pressure, and a holder is attached to one end of the bellows, which is pushed by a bias spring fixed to the opposite side of the frame to which the bellows is attached, and the tip of the holder is a non-magnetic A magnetic core is attached to the tip of the shaft, and the magnetic core constitutes a differential transformer together with a differential coil fixed to a frame on the opposite side of the frame to which the bellows is attached. Therefore, when the bellows moves back and forth due to the pressure of the piping input to the bellows, the holder at the tip of the bellows, the non-magnetic shaft, and the magnetic core also move, and the output of the differential transformer changes in proportion to the displacement of the bellows.

Therefore, compared to the conventional system in which a microswitch is turned on and off by the displacement of the bellows, an output proportional to the displacement can be obtained, and control can be performed in proportion to the displacement.

〔Example〕

Embodiments of the pressure sensor of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of an embodiment of the pressure sensor of the present invention.

A pipe 1 connected to the pipe of an inverter type air conditioner is connected to a bellows 2 that expands and contracts depending on internal pressure to form an airtight chamber. One end of the bellows 2 is fixed to a frame 3, and a holder 4 is fixed to the other end of the bellows 2. A bias spring 5 is installed between the holder 4 and the frame 3, and a bias pressure opposite to the pressure of the refrigerant gas is applied to the bellows 2. Further, a shaft 6 made of a non-magnetic material is fixed to the holder 4, and a magnetic core 7 is fixed to the tip thereof. Further, a coil 9 constituting a differential transformer is fixed at a position facing the bellows 2 of the frame 3, and the magnetic core 7 is arranged at the center thereof.

Here, when the internal pressure due to the refrigerant gas in the pipe 1 rises above atmospheric pressure, the bellows 2 expands and the magnetic core 7
moves through the center of the differential trans group.

In the differential transformer base, an excitation circuit 91 excites an excitation coil, and a rectification circuit 92 rectifies the output of the detection coil to output an output signal. The amount of movement of the magnetic core 7 is determined by the bias spring 5, the spring constant of the bellows 2, and the refrigerant gas pressure P inside the pipe 1. Therefore, the output signal of the rectifier circuit 92 is output in proportion to the refrigerant gas pressure P inside the pipe 1.

Next, as shown in FIG. 2, the output of the air conditioner pressure sensor reed of the present invention is compared with the output of the pressure setting device 21 by the comparator 22, and the deviation value signal is sent to the inverter controller 23.
The rotational speed of the refrigeration compressor 24 is controlled by inputting it to the refrigeration compressor 24.

Below is a blank space.0 Effects of the Invention [Effects of the Invention] As stated above, in an air conditioner using the air conditioner pressure sensor of the present invention, the controlled pressure P is as shown by the solid line Pc in FIG. The refrigeration compressor can be stably controlled within the range of Pp near the control target pressure PR, preventing an abnormal rise in the evaporation temperature, and at the same time preventing the refrigeration compressor from operating in a pressure drop state. This improves the operating efficiency of the machine.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a pressure sensor for an air conditioner showing an embodiment of the present invention. FIG. 2 is a block diagram of an air conditioner control device using the air conditioner pressure sensor according to the present invention. FIG. 3 is a diagram showing changes in controlled pressure. FIG. 4 is a block diagram of an air conditioner control device using a conventional air conditioner pressure sensor. FIG. 5 is a block diagram showing the basic configuration of the air conditioner. FIG. 6 is a sectional view of a conventional pressure sensor for air conditioners. 1, 50.61... Piping, 2.62... Bellows,
3.63...Frame, 4.64...Holder, 5
．． 65...bias spring, 6...shaft,
7... Magnetic core, a... Differential transformer, 9... Coil, 91... Excitation circuit, 92... Rectifier circuit, 20
−=Pressure sensor for air conditioner, 21...pressure setting device, 2
2... Comparator, 23... Inverter control device, 24
... Refrigeration compressor, 41 ... Pressure sensor for detecting upper limit pressure, 42 ... Pressure sensor for detecting lower limit pressure, 43.
... Inverter control device, 44 ... Refrigeration compressor, 51
... AC power supply, 52 ... Inverter control device, 53
... Refrigeration compressor, 54 ... Low pressure side pressure sensor 55
...Indoor heat exchanger, 56...Liquid receiver, 57...Expansion valve, 58...Outdoor heat exchanger, 66...Micro switch, 67...Output cable, Pc... Controlled pressure curve when using the pressure sensor according to the present invention. Figure 1 Figure 2 Patent applicant: Tokin Co., Ltd. Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. In an air conditioner pressure sensor that detects refrigerant gas pressure in order to control the rotation speed of a refrigeration compressor using an inverter device, there is a sensor on one side of the frame that is displaced according to the pressure of refrigerant gas inside the piping. A bellows is provided, a magnetic core is attached to the tip of the bellows, a coil is attached to the frame opposite to the frame on which the bellows is attached, and in combination with the magnetic core, a differential transformer is constructed, and the displacement of the bellows is continuously controlled by the differential transformer. A pressure sensor for an air conditioner, characterized in that the rotation speed of the refrigeration compressor is controlled by converting the electrical signal into an electrical signal and comparing the electrical signal with an electrical signal corresponding to a preset pressure setting value.