WO2016192974A1

WO2016192974A1 - Compressor with a movable oil suction apparatus and a control method

Info

Publication number: WO2016192974A1
Application number: PCT/EP2016/060984
Authority: WO
Inventors: Husnu Kerpicci; Yasam UZUN; Emrah SALMAN
Original assignee: Arcelik Anonim Sirketi
Priority date: 2015-06-02
Filing date: 2016-05-17
Publication date: 2016-12-08

Abstract

The present invention relates to a hermetic type compressor (1) comprising a main motor (2) composed of a stator (3) and a rotor (4); a crankshaft (5) that transfers the movement received from the rotor (4); a piston-rod mechanism (6); a cylinder block (7) that bears the crankshaft (5) and the piston-rod mechanism (6); a casing (8) wherein the oil for lubrication of the movable components and the bearings (Y) is placed; a vertical channel (9) that opens into the crankshaft (5), and a oil suction apparatus (10) that is positioned in the channel (9).

Description

COMPRESSOR WITH A MOVABLE OIL SUCTION APPARATUS AND A CONTROL METHOD

The present invention relates to a compressor, the lubrication of which is improved by means of an oil suction apparatus that is actuated by an auxiliary motor, independently from the crankshaft, and the control method thereof.

In household appliances, preferably in cooling devices, the circulation of the refrigerant fluid used for the refrigeration cycle is provided by a compressor. In hermetic compressors used in cooling devices, the delivery of the lubricating oil to the bearings formed by the movable surfaces is provided by means of an oil suction apparatus. At the stopping time of the compressor, the oil in the crankshaft and the bearings trickles towards the lower casing with the effect of gravity. When the compressor operates again, this situation results in mechanical losses and dry friction in the bearings until the oil suction apparatus sucks the oil in the lower casing again and delivers to the bearings. Furthermore, since sufficient oil cannot be sucked by the oil suction apparatus at low compressor speeds, the required lubrication cannot be provided in the movable components of the compressor and the bearings. This situation adversely affects the efficiency of the compressor, resulting in abrasion and the reduction in expected product life span in movable components and the bearings due to the generated friction.

In the state of the art United States Patent Application No. US2002170779, an oil suction apparatus is disclosed, that is rotated in the reverse direction of the crankshaft by means of the gears. In this embodiment known in the technique, the rotational speed of the oil suction apparatus cannot be controlled independently from the rotational speed of the crankshaft.

The aim of the present invention is the realization of a compressor, wherein lubrication of the movable components and the bearings is improved, and of the control method thereof.

The compressor realized in order to attain the aim of the present invention, explicated in the first claim and the respective claims thereof, comprises a crankshaft that transfers the movement received from the main motor, a cylindrical oil suction apparatus that can rotate around its axis, that is placed inside through the end of the crankshaft immersed into the oil in the casing, the side surface of which is in helical geared shape. The compressor furthermore comprises an auxiliary motor that enables the crankshaft to be rotated in the reverse direction and an electronic control card that provides the controlling of the main motor and the auxiliary motor independently from one another.

By means of the terminal disposed on the compressor casing, the energy and control signals received from the main power supply and the control card are delivered to the auxiliary motor by a cable. In the control card, separate drive and inverter circuits are disposed for the main motor and the auxiliary motor, the motors are enabled to be controlled independently and also in variable speeds.

In the compressor, the auxiliary motor shaft is connected to the oil suction apparatus by means of a pin. The auxiliary motor is housed by means of a ring and a ball bearing disposed in the connection apparatus that provides the connection of the oil suction apparatus to the stator of the main motor. The auxiliary motor is placed into the compressor by means of being seated on the springs disposed on the upper surface of the casing base that attenuate the vibrations in the axial direction.

In the control method of the compressor, when the operate command is delivered to the compressor, the main motor is not operated for a certain predetermined time and the auxiliary motor is operated during this time. When the time is over, the auxiliary motor is stopped and the main motor is operated.

In another compressor control method, the auxiliary motor is activated when the speed of the main motor decreases below a predetermined critical rpm and when the speed of the main motor increases above the said critical rpm, the auxiliary motor is stopped.

Thus, by controlling the auxiliary motor, the oil is enabled to be received by means of the oil suction apparatus and an auxiliary motor that can be controlled independently of the crankshaft movement, in other words of the operation of the compressor, the movable components of the compressor and the bearings are enabled to be lubricated either before the compressor operates or at low compressor speeds the compressor operates, at the predetermined speeds.

By means of the present invention, the amount of oil supplied for the lubrication of the movable components is increased at low main motor speeds before the main motor start-up. When the speed of the main motor increases, the auxiliary motor can be deactivated and the power delivered to the compressor can be decreased since compressor lubrication process reaches a sufficient level. Since sufficient lubrication can be performed at the initial start-up moment by operating the auxiliary motor before the compressor operates, the time required for sucking the oil from the lower casing and delivering the same to the bearings decreases and a sufficient amount of oil can be delivered to the bearings during this time.

The model embodiments related to the compressor and the control method realized in order to attain the aim of the present invention are illustrated in the attached figures, where:

Figure 1 – is the cross-sectional view of the compressor of the present invention.

Figure 2 – is the schematic view of the compressor and the control card of the present invention.

Figure 3 – is the front exploded view of the casing, the crankshaft, the oil suction apparatus, the connection apparatus and the auxiliary motor.

Figure 4 – is the exploded perspective view of the casing, the crankshaft, the oil suction apparatus, the connection apparatus and the auxiliary motor.

Figure 5 – is the front view of the oil suction apparatus and the auxiliary motor.

Figure 6 – is the front view of the crankshaft, the auxiliary motor and the ball bearing.

Figure 7 – is the perspective view of the crankshaft, the connection apparatus, the auxiliary motor, the ring and the ball bearing in the mounted stated.

The elements illustrated in the figures are numbered as follows:

Compressor
Main motor
Stator
Rotor
Crankshaft
Piston – rod mechanism
Cylinder block
Casing
Channel
Oil suction apparatus
Auxiliary motor
Control card
Terminal
Cable
Main motor drive circuit
Auxiliary motor drive circuit
Main motor three phase inverter
Auxiliary motor three phase inverter
Switched-mode power supply (SMPS)
Rectifier
Microcontroller
Auxiliary motor shaft
First hole
Second hole
Pin
Connection apparatus
Foot
Arm
Ring
Ball bearing
Radial resilient member
Axial resilient member

Y: Bearing

P: Power supply unit

The hermetic type compressor (1) comprises a main motor (2) composed of a stator (3) and a rotor (4); a crankshaft (5) that transfers the movement received from the rotor (4); a piston-rod mechanism (6); a cylinder block (7) that bears the crankshaft (5) and the piston-rod mechanism (6); a casing (8) wherein the oil for lubrication of the movable components like the main motor (2), the crankshaft (5), the piston-rod mechanism (6) and the bearings (Y) is placed; a vertical channel (9) that opens from the lower end of the crankshaft (5) that is immersed into the oil in the casing (8) into the crankshaft (5) in the axial direction, and a cylindrical oil suction apparatus (10), the outer periphery of which is in helically geared structure, that is positioned in the channel (9) one inside the other and concentrically with respect to the crankshaft (5), and that extends from the lower end of the crankshaft (5) into the channel (9) .

The compressor (1) of the present invention comprises
- an auxiliary motor (11) that is connected to the oil suction apparatus (10) and that enables the oil suction apparatus (10) to be rotated independently from the crankshaft (5) and in the reverse direction of the crankshaft (4) and
- a control card (12) that enables the main motor (2) and the auxiliary motor (11) to be driven and the auxiliary motor (11) to be controlled independently from the main motor (2).

In an embodiment of the present invention, the compressor (1) comprises the variable speed main motor (2) and the variable speed auxiliary motor (11). The auxiliary motor (11) can be operated at variable speeds for increasing/decreasing oil suction, at the preferred times, for example when the rpm (speed) of the compressor (1) main motor (2) and hence when the oil suction performance is low. Since the auxiliary motor (11) can be controlled independently from the main motor (2), the auxiliary motor (11) can be operated when the main motor (2) is at a stop position before start-up.

The compressor (1) furthermore comprises a terminal (13) that is disposed on the casing (8) and that provides electrical connection with the control card (12) and the power source (P), and a cable (14) that is connected to the terminal (13) and that provides the energization of the auxiliary motor (11) (Figure 1).

During the operation of the compressor (1), at the operation and stop times of the main motor (2), the auxiliary motor (11) rotates the oil suction apparatus (10) disposed inside the crankshaft (5) in the reverse direction of the rotational movement of the crankshaft (5) with the energy received by means of the terminal (13) and the cable (14). The oil suction apparatus (10) is disposed concentrically inside the crankshaft (5) so as to rotate independently from the crankshaft (5). Thus, the oil in the casing (8) can be conveyed through the oil suction apparatus (10) independently from the movement of the main motor (2). When the main motor (2) stops or rotates at low speeds when sufficient oil cannot be pumped, the movable components and the bearings (Y) are effectively lubricated by means of the oil suction apparatus (10) that is activated by the auxiliary motor (11).

The control card (12) comprises a main motor drive circuit (15), an auxiliary motor drive circuit (16), a main motor three phase inverter (17) and an auxiliary motor three phase inverter (18) that enable the main motor (2) and the auxiliary motor (11) to be controlled independently from each other. The control card (12) furthermore comprises a switched mode power supply (SMPS) (19), a rectifier (20) and a microcontroller (12) that are used in controlling the main motor (2) and the auxiliary motor (11) (Figure 2).

In an embodiment of the present invention, the compressor (1) comprises an auxiliary motor shaft (22) that transmits the rotational movement of the auxiliary motor (11) to the oil suction apparatus (10), a first hole (23) arranged at the lower end of the oil suction apparatus (10), a second hole (24) arranged at the upper end of the auxiliary motor shaft (22) and a pin (25) that enables the oil suction apparatus (10) to be mounted to the auxiliary motor shaft (22) by being passed through the first hole (23) and the second hole (24) (Figure 3, Figure 4). The auxiliary motor (11) is operated with the energy received from the terminal (13) and cable (14) connection and the oil suction apparatus (10) connected to the auxiliary motor shaft (22) by the pin (25) is rotated inside the channel (9) in the reverse direction of the crankshaft (5).

In another embodiment of the present invention, the compressor (1) comprises a connection apparatus (26) that enables the oil suction apparatus (10) and the auxiliary motor (11) to be positioned at the lower side of the main motor (2) concentrically with the crankshaft (5) (Figure 3, Figure 4, Figure 7).

The connection apparatus (26) comprises at least two feet (27) fixed to the stator (3) or the casing (8), at least two arms (28) that extend from each foot (27) towards the oil suction apparatus (10), a ring (29) disposed between the arms (28) and at the lower side of the crankshaft (5) and concentric with the crankshaft (5) and whereto the ends of the arms (28) are fastened, and a ball bearing (30) that is disposed inside the ring (29) and that bears the auxiliary motor shaft (22). The auxiliary motor shaft (22) is mounted to the hub of the ball bearing (30) and the ball bearing (30) is mounted into the ring (29). Thus, the auxiliary motor (11) connected to the oil suction apparatus (10) is positioned at the lower side of the crankshaft (5) and concentrically with the crankshaft (5).

In another embodiment of the present invention, the connection apparatus (26) comprises more than one radial resilient member (31), for example springs, that provides the connection between the arms (28) and the ring (29) and that attenuates the vibrations affecting the auxiliary motor (11) in the radial direction.

In another embodiment of the present invention, the compressor (1) comprises at least one axial resilient member (32), for example a spring, that enables the auxiliary motor (11) to be fixed to the base of the casing (8) and that attenuates the vibrations affecting the auxiliary motor (11) in the axial direction. The axial resilient members (32) are disposed between the auxiliary motor (11) and the casing (8), fitted on the oppositely located protrusions (not shown in the figures) below the auxiliary motor (11) and on the upper surface of the base of the casing (8). The radial resilient members (31) and the axial resilient members (32) minimize the effect of the compressor (1) vibrations on the auxiliary motor (11) and hence on the oil suction apparatus (10).

The control method executed by the control card (12) for the control of the compressor (1) of the present invention explicated above comprises the following steps :
- operating the auxiliary motor (11) for a predetermined time period (T1) when the compressor (1) is operated before the main motor (2) starts to operate,
- stopping the operation of the auxiliary motor (11) when the said time period (T1) is over, and
- operating the main motor (2).

The predetermined time period (T1) during which the auxiliary motor (11) is operated before the compressor (1) starts operating is long enough for providing the required lubrication for the compressor (1). In this embodiment, when the operate compressor (1) command is received by the control card (12), first the auxiliary motor (11) is activated and only the auxiliary motor (11) is operated during lubrication time, after this duration the auxiliary motor (11) is stopped and the main motor (2) is operated.

In another embodiment of the present invention, in the control method executed by the control card (12) for controlling the compressor (1), when the speed of the main motor (2) becomes lower than a predetermined critical rpm (Rpm_x), the auxiliary motor (11) is activated. When the speed of the main motor (2) falls below the critical rpm (Rpm_x), the rpm of the auxiliary motor (11) is determined depending on the rpm of the main motor (2). In this embodiment, the rpm of the auxiliary motor (11) is increased or decreased in reverse proportion with the rpm of the main motor (2).As the rpm of the main motor (2) decreases, the rpm of the auxiliary motor (11) is increased and as the rpm of the main motor (2) increases, the rpm of the auxiliary motor (11) is decreased.

In this embodiment, as an example:

If the rpm of the main motor (2) is lower than half of the predetermined critical rpm (Rpm_x) ,

The rpm of the auxiliary motor (11) is calculated by the first formula (2∝) / ((Rpm_x) / (RPM_max )),

If the rpm of the main motor (2) is higher than half of the predetermined critical rpm (Rpm_x) ,

The rpm of the auxiliary motor (11) is calculated by the second formula (∝) / ((Rpm_x) / (RPM_max )). .

In this embodiment,

α symbolizes the nominal rpm (speed) of the auxiliary motor (11),

RPM_max symbolizes the maximum rpm (speed) of the main motor (2).

When the speed of the main motor (2) falls below the predetermined critical rpm (Rpm_x), the control card (12) determines whether or not the speed is below the half of the critical rpm (Rpm_x). If the speed of the main motor (2) is below the half of the critical rpm (Rpm_x), then the auxiliary motor (11) is operated at the speed calculated according the above described first formula. If the speed of the main motor (2) is above the half of the critical rpm (Rpm_x), then the auxiliary motor (11) is operated at the speed calculated according the above described second formula.

If the speed of the main motor (2) is above the predetermined critical operating rpm (Rpm_x), then the auxiliary motor (11) is stopped.

By means of the control method of the present invention, at high main motor (2) speeds wherein the lubrication process is performed without problems, the speed of the auxiliary motor (11) is decreased or altogether stopped thus saving energy.

By means of the present invention, especially in inverter compressors (1) that can operate at variable speeds, the amount oil supplied for lubrication of the movable components and the bearings (Y) is increased at low speeds of the main motor (2). When the speed of the main motor (2) increases, the auxiliary motor (11) is deactivated and the power delivered to the compressor (1) can be decreased since compressor lubrication process reaches a sufficient level. Since sufficient lubrication can be performed at the initial start-up moment by operating the auxiliary motor (11) before the main motor (2) starts to operate, the time required for sucking the oil from the lower casing (8) and delivering to the bearings (Y) decreases and a sufficient amount of oil can be delivered to the bearings (Y) during this time. In the situation the main motor (2) of the compressor (1) changes to start-up position from the stop position and at low cooling requirement in the cooling device, the risk of operating without oil or insufficient lubrication is minimized.

Claims

A compressor (1) comprising a main motor (2) composed of a stator (3) and a rotor (4); a crankshaft (5) that transfers the movement received from the rotor (4); a piston-rod mechanism (6); a cylinder block (7) that bears the crankshaft (5) and the piston-rod mechanism (6); a casing (8) wherein the oil for lubrication of the movable components and the bearings (Y) is placed; a vertical channel (9) that opens into the crankshaft (5) in the axial direction, and a cylindrical oil suction apparatus (10), the outer periphery of which is in helically geared structure, that is positioned in the channel (9) one inside the other and concentrically with respect to the crankshaft (5), characterized in that

- an auxiliary motor (11) that is connected to the oil suction apparatus (10) and that enables the oil suction apparatus (10) to be rotated independently from the crankshaft (5) and in the reverse direction of the crankshaft (4) and

- a control card (12) that enables the main motor (2) and the auxiliary motor (11) to be driven and the auxiliary motor (11) to be controlled independently from the main motor (2).
A compressor (1) as in Claim 1, characterized in that the variable speed main motor (2) and the variable speed auxiliary motor (11).
A compressor (1) as in Claim 1, characterized in that a terminal (13) that is disposed on the casing (8) and that provides electrical connection with the control card (12) and the power source (P), and a cable (14) that is connected to the terminal (13) and that provides the energization of the auxiliary motor (11).
A compressor (1) as in Claim 1, characterized in that the control card (12) comprising a main motor drive circuit (15), an auxiliary motor drive circuit (16), a main motor three phase inverter (17) and an auxiliary motor three phase inverter (18) that enable the main motor (2) and the auxiliary motor (11) to be controlled independently from each other.
A compressor (1) as in Claim 4, characterized in that the control card (12) comprising a switched mode power supply (SMPS) (19), a rectifier (20) and a microcontroller (12) that are used in controlling the main motor (2) and the auxiliary motor (11).
A compressor (1) as in Claim 1, characterized in that an auxiliary motor shaft (22) that transmits the rotational movement of the auxiliary motor (11) to the oil suction apparatus (10), a first hole (23) arranged at the lower end of the oil suction apparatus (10), a second hole (24) arranged at the upper end of the auxiliary motor shaft (22) and a pin (25) that enables the oil suction apparatus (10) to be mounted to the auxiliary motor shaft (22) by being passed through the first hole (23) and the second hole (24).
A compressor (1) as in Claim 1, characterized in that a connection apparatus (26) that enables the oil suction apparatus (10) and the auxiliary motor (11) to positioned at the lower side of the main motor (2) to be concentric with the crankshaft (5), comprising at least two feet (27) fixed to the stator (3) or the casing (8), at least two arms (28) that extend from each foot (27) towards the oil suction apparatus (10), a ring (29) disposed between the arms (28) and at the lower side of the crankshaft (5) and concentric with the crankshaft (5) and whereto the ends of the arms (28) are fastened, and a ball bearing (30) that is disposed inside the ring (29) and that bears the auxiliary motor shaft (22).
A compressor (1) as in Claim 6, characterized in that the connection apparatus (26) comprising more than one radial resilient member (31), for example springs, that provides the connection between the arms (28) and the ring (29) and that attenuates the vibrations affecting the auxiliary motor (11) in the radial direction.
A compressor (1) as in Claim 6, characterized in that at least one axial resilient member (32) that enables the auxiliary motor (11) to be fixed to the base of the casing (8) and that attenuates the vibrations affecting the auxiliary motor (11) in the axial direction.
A control method executed by the control card (12) for a compressor (1) as in any one of the above claims, comprising the following steps:

- operating the auxiliary motor (11) for a predetermined time period (T1) when the compressor (1) is operated before the main motor (2) starts to operate,

- stopping the operation of the auxiliary motor (11) when the said time period (T1) is over, and

- operating the main motor (2).
A control method as in Claim 10, comprising the step of:

- activating the auxiliary motor (11) when the speed of the main motor (2) falls below a predetermined critical rpm (Rpm_x).
A control method as in Claim 11, comprising the step of:

- increasing/decreasing the rpm of the auxiliary motor (11) in reverse proportion to the rpm of the main motor (2) when the speed of the main motor (2) falls below the critical rpm (Rpm_x).
A control method as in Claim 10, comprising the step of:

- stopping the auxiliary motor (11) when the speed of the main motor (2) exceeds the predetermined critical operating rpm (Rpm_x).