JP7474033B2 - air compressor - Google Patents

Description

The present invention relates to an air compressor.

It is known that a screw compressor in which a compression mechanism and an electric motor are housed inside a casing has a terminal assembly installed on the top surface of the casing and a terminal case that houses it, and condensed water generated inside the terminal case is discharged to the outside through a through hole and a drain tube, as described in Patent Document 1, etc.

In addition, a portable air compressor used at construction sites and the like is known that, when work is completed, allows the compressed air remaining in the air tank to be removed by an air duster unit attached to the end of the pressure reducing valve, making it possible to effectively use the air for cleaning tools, etc. This configuration is described in Patent Document 2 and elsewhere.

JP2008-274910 Patent Publication 2014-70583

Portable air compressors are mainly used by carpenters at construction sites to drive nails. Compared to general compressors, these compressors are more likely to be used in semi-outdoor environments. Therefore, the control board may be damaged by various external factors such as rainwater from rainfall, dust from wood and gypsum, or condensation inside the compressor due to use in a high humidity environment. To prevent water droplets and dust from entering from the outside, all sides of the control board can be covered with a casing, but when the mounted elements generate heat, the heat is trapped inside the casing, so there is a possibility that the element's specified temperature will be exceeded and it will be damaged. For this reason, the casing for the control circuit has an open section. If rainwater or dust enters the compressor from the air intake of the compressor, it may enter the casing from the open section of the control board casing and accumulate in the control cover at the bottom of the casing. Water droplets generated by condensation may also accumulate in the control cover. In such cases, it is necessary to remove water droplets and dust from inside the control case to protect the board.

In order to expel trapped water droplets and dust to the outside, compressed air is taken out from inside the tank, and the trapped water droplets and dust inside the control cover are expelled to the outside, preventing damage to the circuit board.

This invention can prevent damage to the control board of a portable compressor caused by external factors such as water droplets and dust, leading to improved product reliability.

An example of a cross-sectional view of a portable air compressor according to a first embodiment of the present invention. FIG. 1 is a top view of an external appearance of a compressor according to a first embodiment of the present invention. 1 is a cross-sectional view of a compressor according to a first embodiment of the present invention; FIG. 1 is a block diagram of a compressor according to a first embodiment of the present invention. 1 is a block diagram showing an example of a compressor configuration according to a first embodiment of the present invention; A flowchart showing an example of an operation of the compressor with an air blow mechanism at the start of operation in the first embodiment of the present invention. FIG. 13 is a diagram showing an example of the configuration of the control group 30 and the control case 32 after the shape change in the third embodiment of the present invention. FIG. 1 is a diagram showing an example of the arrangement of an in-line filter according to the first embodiment of the present invention.

The following describes the embodiment with reference to the drawings.

First, the structure of the portable air compressor according to the first embodiment of the present invention will be described below with reference to Figures 1, 2, and 3.

Figure 1 is an example of a cross-sectional view of a portable air compressor. Figure 1 is composed of a compressor body 1 that compresses air to a large extent, a motor 6 that drives the compressor body 1, and a cooling fan 10 that cools the compressor body 1 and the motor 6.

The compressor body 1 is made up of a crankcase 1A that covers the compressor body 1 and the motor 6, a high-pressure side cylinder 18A and a low-pressure side cylinder 18B that are attached to the crankcase 1A, and a bearing housing 5 that is fitted to the crankcase 1A on the side opposite the motor 6.

A shaft (rotating shaft) 6A of a motor 6 passes through the crankcase 1A and is supported by a bearing 3 arranged in the crankcase 1A and a bearing 4 arranged in a bearing housing 5.

Eccentrics 16A, 16B and balance 17 are fixed to the center of shaft 6A by key 12 and rotate together with shaft 6A. Connecting rod sets 14A, 14B are rotatably connected to eccentrics 16A, 16B via bearings 15A, 15B. Piston rings 13 are provided on the outer periphery of the piston of connecting rod set 14A to seal and compress the air in the working chamber.

A high pressure cylinder 18A and a low pressure cylinder 18B are attached to the crankcase so as to face each other with the crankcase in between. A flange 19 for mounting the cylinder 18 is provided on the crankcase 1A, and the cylinder 18 is provided with an air valve 20, a cylinder head 21, and a through bolt 22 for connecting the cylinder head 21 to the cylinder 18. The cylinder 18 , the air valve 20, and the cylinder head 21 are fixed to the flange 19 by the through bolt 22 to form a compression chamber 23.

The motor 6 has a stator 2, a shaft 6A, a key 7, a rotor 8, and a washer 9. The stator 2 is directly fixed to one end of the crankcase 1A, and the rotor 8 is attached to one end of the shaft 6A via a key 7. The rotor 8 is fixed in the axial direction by the washer 9 and a fan shaft 11 for mounting a cooling fan 10.

The cooling fan 10 supplies cooling air to the inside of the cooling cover 26, and cools the components of the tank-integrated air compressor, such as the compressor body 1 and the storage tanks 24, 25. The cooling fan 10 is attached to the end of the shaft 6A by a fan shaft 11, and rotates as the shaft 6A rotates.

2 shows a top view of the portable air compressor. The compressor body 1 is disposed on top of the storage tanks 24 and 25, and is covered by a cooling cover 26. After the power is turned on, the compressor body 1 operates by pressing a switch disposed on an operation unit 29.

The operation of the compressor body 1 in this embodiment will be described. In this embodiment, when the shaft 6A rotates due to the drive of the rotor 8, the eccentric 16 causes the connecting rod set 14 and the piston ring 13 to reciprocate in the compression chamber 23. During the intake stroke from top dead center to bottom dead center, the piston ring 13 draws air into the compression chamber 23 through the cylinder head 21 and air valve 20, and conversely, during the exhaust stroke toward top dead center, the intake air is compressed and exhausted through the air valve 20 and cylinder head 21. The air exhausted through the cylinder head 21 is stored in the storage tanks 24, 25.

Next, the control of the compressor body 1 by the control group 30 in this embodiment will be described with reference to FIG. 3. FIG. 3 is a cross-sectional view of a portable air compressor. In this embodiment, the compressor body 1 is disposed above the two storage tanks 24, 25, and the control group 30 that controls the operation of the tank-integrated air compressor is disposed between the two storage tanks 24, 25.

A control case 32 for protecting the control group 30 is attached to the bottom of the control group 30. The tank-integrated air compressor employs a pressure operation control method, and the control group 30 controls operation according to the pressure sensed by a pressure sensor 31 attached to the storage tank 24.

Next, the embodiment and operation of the present invention will be described with reference to Figures 2, 4, 5, and 6. A normal pressure reducing valve 33 and a high pressure reducing valve 34 are attached to the storage tank 24, and a normal pressure gauge 35 and a high pressure pressure gauge 36 are attached to each of them. Furthermore, normal pressure couplers 37 and high pressure couplers 38 are attached in pairs, and the user can take out the compressed air from the storage tanks 24 and 25 by attaching a corresponding hose and nail gun to the end of the coupler. In the present invention, as shown in Figure 4, an air blow mechanism 45 for inside the control cover is provided at the lower part of the normal pressure reducing valve 33, which is composed of a T-shaped joint 39, a pressure reducing valve 40, a solenoid valve 41, and an in-line filter 43.

The control flow of the air blow mechanism 45 is shown in Fig. 6. In this embodiment, when a user starts work, he or she inserts the plug into an outlet to turn on the compressor ("power on") and starts operation of the compressor main body 1 with the operation unit 29 ("operation SwON"), thereby starting the operation of the compressor ("compressor operation start").

After the compressor starts operating, the solenoid valve 41 attached to the pressure reducing valve 40 is opened ("solenoid valve open") for a certain period of time (e.g., about 3 seconds) immediately after operation, and air is blown through the in-line filter 43.

After a certain period of time has elapsed, the solenoid valve is closed ("Solenoid valve closed"), and normal operation is started. In normal operation, it is determined whether the pressure in the storage tanks 24, 25 exceeds the target pressure ("Tank pressure > target pressure"), and if it does not exceed the target pressure ("No"), the determination continues, and if it exceeds the target pressure ("Yes"), the compressor is stopped ("Compressor stopped").

After the compressor is stopped, it is determined whether the pressure in the storage tanks 24, 25 has fallen below the restart pressure P0 ("Tank pressure < restart pressure"), and if it has not fallen below that pressure ("No"), the determination continues, and if it has fallen below that pressure ("Yes"), the compressor is restarted ("Restart").

The control group 30 has an area in a memory unit (not shown) for storing the number of restarts, and upon restart, the control group 30 increments this number.

It then determines whether the number of restarts is a predetermined value ("Number of restarts = N x 10"), and if it is not the predetermined value ("No"), it returns to the determination of "Tank internal pressure > target pressure", and if it is the predetermined value ("Yes"), it opens the solenoid valve for a certain period of time (e.g., about 1 second) ("Solenoid valve open"), and after the certain period of time it closes the solenoid valve ("Solenoid valve close"), and returns to the determination of "Tank internal pressure > target pressure".

The above operation allows water droplets and dust trapped inside the control case at the start of work to be expelled to the outside.

Here, if the exhaust air contains a lot of moisture, the in-line filter 43 will absorb moisture, losing its filtering effect and increasing the moisture content of the air blown into the control group 30. To avoid this, it is necessary to dry the in-line filter 43 by utilizing the heat of the storage tank 24 adjacent to the in-line filter 43.

The storage tank 24 is prone to becoming hot because high-temperature compressed air is stored therein after compression, and the control group 30 generates heat due to the increase in current caused by driving the compressor. Therefore, by placing an in-line filter 43 between the control group 30 and the storage tank 24, the in-line filter 43 can be heated to a high temperature as shown in FIG. 8, and the heat can be transferred to the desiccant in the in-line filter 43 , causing it to dry.

However, this compressor is mainly used at construction sites, where dust from wood, gypsum, etc., and water droplets from sudden rainfall may enter during work. Therefore, depending on the total number of restarts (for example, the 10th, 20th, ...), the solenoid valve is controlled to open at a specified restart, thereby appropriately discharging water droplets and dust that have entered during work. This prevents damage to the control board caused by water droplets and dust that have become mixed in during work.

The target pressure and restart pressure can be changed depending on the operating mode of the compressor. By setting the restart pressure higher than standard operation, it is possible to prevent compressed air from running out when usage is high, and by setting the target pressure lower than standard operation, it is possible to improve quietness when usage of compressed air is low.

A second embodiment of the present invention will be described with reference to Figures 3 and 7. In a portable compressor capable of discharging water droplets and dust from within the control case 32 to the outside under certain circumstances by means of an air blow mechanism 45 attached to the lower part of the normal pressure reducing valve 33, the shape of the control case 32 is changed to facilitate directing the water droplets inside in any direction. In the first embodiment, when the control case 32 is attached between the storage tanks 24 and 25 together with the control group 30, the bottom surface of the control case 32 is configured to be parallel to the ground.

In this case, if there is no air blow from the air blow mechanism 45, the water droplets and dust trapped inside the control case 32 will be discharged to some extent due to the vibration caused by the operation of the compressor, and will only be discharged outside the control case 32 if the compressor is tilted by the user lifting it, and water droplets and dust will tend to accumulate inside the case during periods when air is not being blown. Therefore, by designing the bottom surface of the control case 32 to be inclined relative to the horizontal plane, it is possible to make it easier for water droplets trapped inside the control case 32 to move in a specific direction.

As shown in Figure 7, for example, by tilting the bottom surface of the control case 32 by about 5 degrees with respect to the ground from upwind to downwind of the air blow mechanism, water droplets can be made to flow more easily in one direction. By using the air blow mechanism in this way, the direction of the tilt makes it easier to move water droplets and dust, and the product can be protected from water droplets and dust.

As for the layout inside the control case 32, as shown in Figure 7, although the power cord is waterproofed, it is best to keep it from getting wet as much as possible. By arranging these parts at the top of the inclined surface, the risk of the power cord becoming wet and causing a short circuit can be reduced. This is similar to the first embodiment, but safety can be further improved by arranging the main components of the control board in the area at the top left of Figure 7, where the effect of air blowing to expel foreign objects is high.

The material of the control case 32 may be changed to further improve the water droplet discharge effect achieved by inclining the bottom surface of the control case 32. For example, attaching a resin plate to the bottom surface or making the control case 32 itself out of resin increases water repellency, making it easier to move water droplets. Alternatively, using a highly hydrophilic material such as resin for the bottom surface can make it easier for water droplets to be discharged during periods when air is not being blown.

The control case can be made of resin, making it lighter and changing its shape, allowing it to be fitted into the part that holds the control board in place with a claw-like shape. Alternatively, a water-repellent coating can be applied to the inside of an aluminum sheet metal case, providing the same effect as using resin, making it possible to protect the control board at low cost.

Reference Signs List 1 Compressor body 2 Stator 3, 4 Bearing 5 Bearing housing 6 Motor 6A Shaft 10 Cooling fan 13 Piston ring 14 Connecting rod set 16 Eccentric 18 Cylinder 20 Air valve 21 Cylinder head 24, 25 Storage tank 26 Cooling cover 29 Operation unit 30 Control set 31 Pressure sensor 32 Control case
33 Normal pressure reducing valve 34 High pressure reducing valve 35 Normal pressure pressure gauge 36 High pressure pressure gauge 37 Normal pressure coupler 38 High pressure coupler 39 T-joint 40 Pressure reducing valve 41 Solenoid valve 42 Elbow 43 In-line filter 44 Discharge pipe 45 Air blow mechanism

Claims (7)

A compressor body,
a tank for storing the gas compressed by the compressor body;
A control group for controlling the compressor body;
an air blowing mechanism having one end connected to the tank and the other end facing the control group;
The air blow mechanism has an electromagnetic valve whose opening and closing is controlled by the control group,
The control group opens the solenoid valve for a predetermined period of time when the compressor body is restarted. The compressor according to claim 1, further comprising a pressure reducing valve between the solenoid valve and the tank. The compressor according to claim 2, further comprising a filter downstream of the solenoid valve. 2. The compressor according to claim 1, wherein the control group opens the solenoid valve for a predetermined period of time when the compressor body is started. 2. The compressor of claim 1, wherein the protective member below the control set is not a horizontal surface . The compressor according to claim 5, wherein the upper surface of the protective member is water-repellent. The compressor according to claim 5, in which the protective member is made of resin.

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