JPH0113830Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an auto-relief device for a compressor, which is a protection device for an oil-lubricated compressor used in construction machinery and the like. Some compressors are oil-lubricated, in which lubricating oil is mixed in and circulated within the compressor and air tank in order to lubricate each part and cool down the heat of compression. In this type of compressor driven by a prime mover, when the prime mover stops, air pressure causes the compressor to fill with oil, causing an accident in which the compressor is damaged when the compressor is next started. Therefore, conventionally, when the prime mover is an engine, the air tank pressure is released by a switching valve after detecting a drop in engine oil pressure due to a drop in engine speed, or via a relay connected to the N terminal of the motor as a prime mover. Measures are taken to detect engine stoppage and release the air tank pressure using an electromagnetic switching valve.

On the other hand, when a compressor is mounted on a construction machine or the like, it is necessary to use a single prime mover to drive various equipment such as a hydraulic pump, and a transfer is often used to take a plurality of output shafts from the prime mover. Furthermore, in order to improve maintainability and suppress the starting torque of the prime mover, a clutch is often installed between the prime mover and the transfer, or between the transfer and the compressor drive shaft. In such a case, if the clutch is disengaged while the compressor is running, problems similar to those caused when the engine is stopped will occur.

In order to solve this problem, the present invention was devised to detect the rotation speed of the compressor with a rotation sensor installed on the drive shaft of the compressor, and if the rotation speed is less than the set rotation speed, the signal is transmitted to the air. The present invention aims to provide an auto-relief device for a compressor that transmits air pressure in an air tank to the atmosphere from a circuit and releases it to the atmosphere to prevent damage to the compressor at the next startup.

Therefore, the compressor auto-relief device of the present invention is an oil-lubricated compressor protection device that supplies lubricating oil separated into gas and liquid from an air tank to the compressor in order to lubricate each part of the compressor and cool down the heat of compression. , an air circuit connected from the compressor to an external load via an air tank, a rotation sensor disposed on the compressor drive shaft, and an air bleed means connected to the rotation sensor to bleed air from the air circuit when the rotation decreases. The main point is that the system is equipped with the following.

Further, with the above-described configuration, the air pressure in the air tank is released to the atmosphere as the rotational speed of the compressor decreases, so even if the compressor stops, oil will not fill up in the compressor due to air pressure.

Embodiments of the present invention will be described in detail below with reference to the drawings.

The drawing is a circuit diagram showing an embodiment of the present invention.

1 is a prime mover, 2 is a clutch, 3 is a transfer connected to the prime mover 1 via the clutch 2, 4 is a compressor connected to the transfer 3, 5 is connected to the compressor 4, and is also connected to an external load (not shown). An air tank, 6 a pressure regulating valve, and 7 a safety valve.

8 is a lubricating oil pump connected to the compressor 4, 9 is a check valve, and 10 is a cooler, which circulates lubricating oil between the compressor 4 and the air tank 5. Note that 11 is an air cleaner.

12 is an air tank 5 and an external load (not shown)
A switching valve 13 is an auto-relief valve installed in a circuit branched from the air circuit between The solenoid of valve 13 is connected to a power source via prime mover start switch 14 and auto-relief controller 15.

Reference numeral 16 denotes a rotation sensor of the magnetic pickup, which is disposed near the compressor drive shaft and connected to the auto-relief controller 15.

Next, to explain its function and effect, when the prime mover start switch 14 is turned on, the electromagnetic switching valve 13 is powered on and energized via the auto-relief controller 15, and the switching valve 13 changes from the illustrated position to the right port position. It is shut off to prevent pilot pressure from being applied. The prime mover 1 is driven, and the clutch 2
When the driving force is transmitted to the compressor 4, the compressor 4 and lubricating oil pump 8 are driven, and the air and lubricating oil are separated in the air tank 5, and the air is connected to the air circuit, pressure regulating valve 6, etc. to the external load circuit. In this case, a switching valve 12 and an electromagnetic switching valve 1 are provided in a circuit branched from the air circuit.
At 3, the pressurized air is cut off. Note that lubricating oil is circulated between the compressor 4 and the air tank 5.

When it becomes necessary to disengage the clutch 2, the rotation of the compressor drive shaft decreases when the clutch 2 is disengaged, and the rotation sensor 16 detects this and issues a command signal to the auto-relief controller 15 to decrease the rotation. Based on this command signal, the auto-relief controller 15 cuts off the power to the solenoid of the electromagnetic switching valve 13, switches the electromagnetic switching valve 13 to the illustrated port position, and applies pilot pressure to the switching valve 12 with pressurized air from the air circuit. Add. This pilot pressure causes the switching valve to switch from the illustrated port position to the right port position, and the pressurized air in the air circuit is released to the atmosphere by the switching valve, and the pressure in the air circuit and air tank 5 is released. Since the pressure of the lubricating oil is released, it is not pushed into the rotor of the compressor 4, and damage to the rotor is prevented.

In short, according to the present invention, an air circuit is connected from the compressor to an external load via an air tank, a rotation sensor is installed on the compressor drive shaft, and the air circuit is connected to the rotation sensor to bleed air from the air circuit when the rotation speed decreases. Since the compressor is equipped with an air bleed means, the air can be bleed as the rotation of the compressor decreases, thereby preventing the compressor from being filled with oil at the next startup and preventing damage to the compressor rotor.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Prime mover, 2... Clutch, 3... Transfer, 4... Compressor, 5... Air tank, 8... Lubricating oil pump, 12... Switching valve, 13
...Auto relief controller, 16...Rotation sensor.

Claims (1)

[Scope of utility model registration request] In a protection device for an oil-lubricated compressor, in which gas-liquid separated lubricating oil is supplied from an air tank to the compressor in order to lubricate each part of the compressor and cool the heat of compression, the compressor is connected to an external load via the air tank. An auto-relief device for a compressor, comprising an air circuit, a rotation sensor disposed on a compressor drive shaft, and an air bleed means connected to the rotation sensor to bleed air from the air circuit when the rotation decreases. .