KR20090048359A - Pumping unit and corresponding heating device - Google Patents

Abstract

The unit (1) has a single staged dry vacuum pump (2) e.g. single staged bilobed root pump, including a compression stage body (13) provided with gas inlet and outlet (15, 17). A heating unit has removable heating resistors (24, 29) arranged at the inlet and the outlet, respectively, in planes that are parallel between them and are perpendicular to directions (19, 21) of gas to be pumped to heat the body by thermal diffusion between the inlet and the outlet, where the resistors are in the form of circular arc shaped bands.

Description

Pumping unit and corresponding heating device {PUMPING UNIT AND CORRESPONDING HEATING DEVICE}

The present invention relates to a pumping unit comprising a dry single stage vacuum pump such as a Roots rotating-lobe pump. The invention also relates to a corresponding heating device.

Dry vacuum pumps are used, in particular, for the production of semiconductors, flat screens or photovoltaic substrates, with a negligible amount of abrasive powder.

Among existing vacuum pumps, there is a distinction between single stage pumps with only one compression stage, so that the gas to be pumped is moved between the gas inlet and the gas outlet. For example, rotary lobe pumps, also known as "Roots" pumps with two or three lobes (double lobes, triple lobes) are known.

Generally speaking, the root rotary-lobe pump has two rotors that are the same in cross section and rotate in opposite directions within the stator. As these rotors rotate, the sucked gas is trapped in the open space found between the rotor and the stator and then escapes through the outlet. The pump operates without any mechanical contact between the rotor and the pump body, which can result in oil not being completely present from the compression chamber.

If these pumps have no mechanical contact between the stator and lobe rotor, but operate with very small clearances between them, these pumps may be used for contaminating processes such as semiconductor processes, more specifically for low pressure chemical vapor deposition (LPCVD), Special configuration, especially with regard to temperature, when used in chemical vapor deposition (CVD) processes including atomic layer deposition (ALD), metal-organic chemical vapor deposition (MOCVD) and plasma enhanced chemical vapor deposition (PECVD) processes need.

These processes preferably use gases in which condensation into powder or solidification is maintained. This is because a significant accumulation of powder on the moving part of the compression stage causes the pump to stop very quickly, especially through mechanical interruption. For this reason, it is important to leave a functional gap inside the compression stage of the pump to ensure maximum operating life. Reducing the rate at which the pump is stopped due to powder generation processes is important to ensure that the manufacturing process is running smoothly.

One solution to achieve this consists in maintaining the gas at a high temperature sufficient to preserve the type of gas that can initiate or condense chemical reactions in the compression stage.

However, this practice is not always possible with single stage pumps. In particular, in semiconductor processes such as LPCVD, the thermal energy released by compression is not always sufficient to keep the temperature of the pump body sufficiently high as a result of low pressure values and flow rate values.

In order to improve this disadvantage, it is known to thermally insulate the main body of the pump using an insulation or a heating lid as described, for example, in Japanese Patent Application Laid-Open No. 2007-262906. The heating sheath is defined as a metal wire sandwiched between the fabric layers. However, these covers have the disadvantage of being bulky and expensive. In addition, the efficiency and heating uniformity of the heating shroud depends on how the heating shroud is mounted, and poor contact between the shroud and the pump body may create a low temperature region where gas can condense.

Therefore, the pump is often provided with a casing at a predetermined angle, and its lid is almost impossible to accurately adjust.

Moreover, in addition to the requirement to maintain the gas circulating in the pump at a predetermined temperature, there is also a need to cool not only the lubricant but also certain specific functional areas of the pump such as bearings, gears and motors.

Thus, it should be noted that the heating shroud is not always suitable, especially for small single stage pumps, since it makes cooling of the functional area less efficient. Therefore, cooling results in a temperature profile on the pump body that even slightly encourages the production of deposits.

Accordingly, it is an object of the present invention to describe a pumping unit capable of keeping the functional area and the lubricant at a low temperature while at the same time the heating is optimized to prevent mechanical malfunctions, such as mechanical interruption.

To this end, the object of the invention comprises a compression stage casing having a gas inlet and a gas outlet, the inlet flange outlet and the outlet flange joint respectively located at the gas inlet and gas outlet, and heating means for heating the vacuum pump. It is a pumping unit having a dry single stage vacuum pump having a.

According to the invention, said heating means are respectively arranged at said gas inlet and gas outlet perpendicular to the direction of the gas to be pumped in planes parallel to each other to heat the body of the pump by heat diffusion between said gas inlet and gas outlet. It has two heating resistors.

According to another feature of the pumping unit,

The heating resistor is centered about an axis which defines the general direction in which the gas circulates;

The pumping unit has at least one heating resistor in the shape of an arc strip arranged at the inlet flange outlet and the outlet flange joint such that the compression end casing can be heated by heat diffusion between the gas inlet and the gas outlet;

Said flanges are arranged in parallel planes such that the two heating resistors are arranged perpendicular to the direction of the gas to be pumped in a plane parallel to each other;

The at least one heating resistor has a plurality of holes for attaching the heating resistor to the inlet flange joint and / or the outlet flange joint;

The heating resistor is attached to the inlet flange joint and / or the outlet flange joint by a retaining screw and a spacer disposed between the head of the heating resistor and the retaining screw;

At least one heating resistor is integrated in the inlet flange joint and / or the outlet flange joint;

The pumping unit has a circuit for cooling the motor 3, two oil pans 5, 6 and bearings 7, 9, said cooling circuit first comprising the motor 3, oil pans 5, 6. And a thermal gradient between the bearings 7, 9 and then between the compression end casing 13;

The pumping unit has a temperature sensor and a temperature controller, which can control the power of the heating resistor to control the temperature of the compression stage casing of the pump.

Another object of the present invention is a heating device for a dry single stage vacuum pump, comprising a compression stage casing having a gas inlet and a gas outlet, each having an inlet flange joint and an outlet flange joint at the gas inlet and gas outlet.

According to the present invention, the heating device is provided with two gas outlets and two gas outlets respectively disposed perpendicular to the direction of the gas to be pumped in planes parallel to each other to heat the body of the pump by heat diffusion between the gas inlet and the gas outlet. A heating resistor is provided.

In one variant, at least one heating resistor is arcuate strip shaped.

In another variant, the at least one heating resistor has a plurality of holes so that it can be attached to the inlet flange joint and / or the outlet flange joint of the pumping unit described above.

The heating device is advantageously provided with a temperature controller and a temperature sensor capable of controlling the power of the heating resistor.

Other advantages and features will become apparent upon reading the detailed description of the invention as well as the accompanying drawings.

According to the present invention, it is possible to provide a pumping unit capable of keeping the functional area and the lubricating oil at a low temperature while optimizing heating to prevent mechanical malfunctions, such as mechanical interruption.

1 shows a pumping unit 1 with a dry single stage vacuum pump 2, an inlet flange joint 16 and an outlet flange joint 18.

The vacuum pump 2 has a motor 3, two oil pans 5, 6, two bearings 7, 9 and a compression stage 11.

The motor 3, oil pans 5, 6 and bearings 7, 9, in particular, utilize liquid circulating between the oil pans 5, 6 and the bearings 7, 9, such as water at room temperature. It is cooled by the cooling circuit 12.

The compression stage 11 has a compression stage casing 13 in which two rotors (not shown) can rotate inside.

The compression stage casing 13 has a gas inlet 15 disposed above the compression stage 11 and a gas outlet 17 disposed below the compression stage 11 (FIG. 1).

In operation, the gas to be pumped can be sucked from the gas inlet 15 of the compression stage 11 (arrow 19) towards the gas outlet 17 (arrow 21).

The inlet flange joint 16 is arranged at the inlet 15 of the vacuum pump 2, and the outlet flange joint 18 is arranged at the outlet 17 of the vacuum pump 2.

The outlet flange joint 18 has an outlet flange 28 which connects the outlet 17 of the pump 2 to a vacuum line intended to be connected to the inlet of the main vacuum pump.

In general, a high flow rate single stage vacuum pump 2 is used when the flow rate is sequentially connected to a main vacuum pump (not shown) capable of releasing gas pumped to atmospheric pressure.

The inlet flange joint 16 has an inlet flange 26 which connects the inlet 15 of the pump 2 to a gas intake vacuum line, for example starting from the process chamber.

Of course, the invention also applies to any type of dry single stage vacuum pump having a rotary lobe, such as a single stage root pump having two or more lobes.

According to one embodiment of the invention, the pumping unit 1 is a first heating resistor which is part of a strip shape of an arc arranged in the outlet flange joint 18 so as to heat the compression end casing 13 by heat diffusion. (24; see FIG. 2).

In this way, the surface heated by the heating resistor 24 has its maximum in the gas flow paths (arrows 19, 21) at the outlet 17 (FIG. 1).

Moreover, the axial form factor in the direction of the pumped gas flows 19 and 21 can be minimized to connect the inlet of the main pump as close as possible to the single stage vacuum pump, thereby reducing the shape factor of the pumping array. Can be.

The compression stage casing 13 is heated at the outlet 17, which is the most important area of the pump 2, assuming that the gas in this area is high pressure and thus more condensed.

It is also ensured that the heating resistors 24 are always arranged in the same way on the pump, which depends on how the contact amount between the heating resistors 24 and the outlet flange joint 18 is installed, as in the case of the prior art. It doesn't depend.

In addition, heating through electrical resistance allows the compression stage casing 13 of the pump 2 to reach a predetermined operating temperature rapidly, reducing the time required for starting the vacuum pump 2.

Advantageously, as shown in FIGS. 3 and 4, the heating resistor 24 is disposed in the outlet flange 28 of the outlet flange joint 18. The heating resistor is also advantageously arranged to be in contact with the surface corresponding to the outlet flange 28.

The corresponding surface of the outlet flange 28 has approximately the same dimensions as the surface of the heating register 24 to optimize the surface to be heated.

The pumping unit 1 further comprises a second heating resistor 29 arranged at the gas inlet 15 to enable the compression stage casing 13 to be heated by heat diffusion between the inlet 15 and the outlet 17. Equipped.

In one variant shown in FIG. 1, the pumping unit 1 also allows the compression end casing 13 to be heated by heat diffusion between the inlet 15 and the outlet 17. And a second heating resistor 29 arranged in the shape of an arc strip.

Advantageously, the first heating resistor 24 is arranged at the outlet 17 and the second heating resistor 29 is arranged at the inlet flange 28 and in contact with the corresponding surface of the flange 26. desirable.

In this way, the targeted heating is achieved through heat diffusion between the inlet 15 and the outlet 17. Therefore, since the pump 2 has only one compression stage 11, the compression stage casing 13 is heated in all the regions where the gas circulates, so that the compression stage casing 13 is a gas so as not to condense the gas. It is guaranteed that it is heated anywhere it circulates.

In addition, in the region where gas does not circulate, the pump 2 is cooled normally to satisfy both the requirement for heating the compression stage casing 13 and the requirement for cooling the target functional region. In this way, a thermal gradient is maintained first between the motor 3 and the oil pans 5, 6 and then between the compression stage casing 13.

It is also ensured that the heating profile can be controlled and regenerated.

Advantageously, as shown in FIG. 1, the flange joints 16, 18 are arranged in parallel planes such that both heating resistors 24, 29 are arranged in planes parallel to each other and in the direction of the gas to be pumped. Are arranged perpendicular to (19, 21).

Thus, the heating resistors 24, 29 are arranged on both sides of the gas circulating in the compression stage 11 and are symmetrical in the compression stage casing 13 along the axis 25 of the pumped gas flows 19, 21. To achieve a typical thermal profile.

Preferably, the second heating resistor 29 is also shaped like an arc of a strip, so as to optimize the surface to be heated like the first heating resistor 24 disposed at the outlet 17.

The heating resistors 24, 29 are centered about an axis 25, preferably a linear axis, which defines the general direction 19, 21 in which the gas flows.

Moreover, the heating resistors 24, 29 may be attached to the inlet flange joint 16 and / or the outlet flange joint 18. In this manner, the at least one heating resistor 24, 29 has a plurality of holes that attach the heating resistor 24, 29 to the inlet flange joint 16 and / or the outlet flange joint 18.

2 to 4 show four holes 31 corresponding to four holes for attaching the outlet flange 28 to attach the heating resistor 24 to the outlet flange joint 18 via the retaining screw 30. A heating resistor 24 is shown.

It is advantageous for the pumping unit 1 to have a plurality of spacers 27. Preferably, at least one ring-shaped spacer 27 is arranged around each hole 31.

The spacer 27 is disposed between the heating resistor 24 and the head of the retaining screw 30 to ensure that thermal contact can be regenerated between the resistor 24 and the flanges 26, 28.

In addition, the spacers 27 can limit the movement of the retaining screws 30, thereby preventing them from colliding with the heating resistors 24, 29 when the retaining screws are attached to the flanges 26, 28.

The heating resistors 24, 29 can be formed, for example, by resistor wires molded in an electrically insulating sheath, the heating resistors being attached to the surface opposite the surface facing the flange joint 16 or 18, For example silicon.

By arranging the retaining plate to clamp the heating resistors 24, 29 against the flange joints 16, 18, the heat transfer between the heating resistors 24, 29 and the flange joints 16, 18 can be further optimized. .

In this way, detachable heating resistors 24 and 29 are achieved that can be easily replaced in case of failure.

Alternatively, at least one heating resistor (not shown) is integrated into the inlet flange joint 16 and / or the outlet flange joint 18.

In the case of the heating resistors 24, 29 attached or integrated to the flange joints 16, 18, the standard single stage vacuum pump 2 without the need to improve the vacuum pump 2 or its inlet 15 or outlet 17. ) Can be installed.

Advantageously, the values of the heating resistors 24, 29 are selected to enable the temperature of the compression stage casing 13 to be maintained at 50 ° C. to 120 ° C.

In addition, the pumping unit 1 is advantageously configured to have a temperature sensor and a temperature controller (not shown), said temperature controller in particular measuring the sensor so as to control the temperature of the compression stage casing 13 of the pump 2. The power of the heating resistors 24 and 29 can be controlled through the controller.

To achieve this, a temperature sensor, such as a K or R type thermocouple or a platinum resistance thermometer, contacts the heating resistors 24, 29 or the casing body 13, advantageously in contact with the flange joint surfaces 16 and / or 18. Is arranged to.

Preferably, the temperature sensor is integrated into the heating resistors 24, 29 by welding or the like.

The temperature controller can also adjust the temperature of the heating resistors 24, 29 using conventional PID control loops.

In the case of a temperature controller, it is possible to absorb temperature fluctuations that occur as the process proceeds.

This fluctuation can result from a drop in the speed of the pump 2, thereby lowering the temperature, which can be caused by a decrease in the pressure or flow of gas at the inlet 15. Conversely, this variation can result from an increase in heating power in the flow of the medium pump.

Temperature control makes it possible to avoid overheating of the body 13 of the pump 2, which not only uses high energy but also the functional areas 3, 5, 6 of the pump 2 which must be kept at a lower temperature. , 7, 8, 9).

Thus, the location of the heating resistors 24, 29 has been studied to ensure symmetry in the heat profile of the pump body to prevent deposits and to avoid stopping the pump. This ensures that the required temperature in the compression stage casing 13 of the pump 2 is achieved while efficient cooling is possible in the functional regions 3, 5, 6, 7, 8, 9. In particular, the cooling of the bearings 7, 9 should ensure a temperature low enough to ensure that the ball bearings are kept in working order.

Moreover, when the temperature of the casing 13 of the pump 2 is stable, this minimizes the thermal fluctuations of the main body 13 of the pump 2 which may be harmful.

Further, temperature control can keep the temperature of the compression stage casing 13 high, including during the maintenance state of the pump 2 when the pump 2 is stopped, and may occur when the vacuum pump 2 is restarted. Limit the risk of outages.

This precise temperature control is only possible by specially configuring the heating resistors 24, 29 to have the area to be heated. Thus, the pumping unit 1 is arranged parallel to the outlet flange joint 18 and the inlet flange joint 16 and perpendicular to the direction of the gas to be pumped, and is preferably the first heating resistor, preferably in the shape of an arc strip. 24 and a second heating resistor 29, it is possible to heat the compression stage casing 13 through heat diffusion, which is heated in a controlled manner.

1 is a side view of the pumping unit of the present invention,

2 is a perspective view of one of the heating resistors of the present invention;

3 and 4 are respectively a top perspective view and a bottom perspective view of the outlet flange in one embodiment;

Explanation of symbols for the main parts of the drawings

1: pumping unit 2: vacuum pump

3: motor 5, 6: oil pan

7, 9: bearing 11: compression end

12 cooling circuit 13 compression stage casing

15 gas inlet 16 inlet flange joint

17 gas outlet 18 outlet flange joint

24, 29: heating resistor

Claims (10)

A pumping unit having a dry single stage vacuum pump (2) comprising a compression stage casing (13) having a gas inlet (15) and a gas outlet (17), each of which is provided at the gas inlet (15) and the gas outlet (17). In the pumping unit, comprising: an inlet flange joint 16 and an outlet flange joint 18, and heating means for heating the vacuum pump, The heating means is adapted perpendicularly to the directions 19, 21 of the gas to be pumped in planes parallel to each other to heat the compression end casing 13 by heat diffusion between the gas inlet 15 and the gas outlet 17. Characterized by having two heating resistors 24, 29 arranged at the gas inlet 15 and the gas outlet 17, respectively. Pumping unit. The method of claim 1, The heating resistors 24, 29 are centered about an axis 25 which defines the general direction 19, 21 in which the gas circulates. Pumping unit. The method according to claim 1 or 2, The at least one heating resistor 24, 29 has a circular arc strip shape disposed at the outlet flange joint 18 and the inlet flange joint 16. Pumping unit. The method of claim 3, wherein The at least one heating resistor 24, 29 has a plurality of holes 31 for attaching the heating resistors 24, 29 to the inlet flange joint 16 and / or the outlet flange joint 18. Pumping unit. The method of claim 4, wherein The heating resistors 24, 29 are provided with an inlet flange joint 16 by a retaining screw 30 and a spacer 27 disposed between the heating resistors 24, 29 and the head of the retaining screw 30. And / or attached to the outlet flange joint 18 Pumping unit. The method according to any one of claims 1 to 3, At least one heating resistor is integrated with the inlet flange joint 16 and / or the outlet flange joint 18. Pumping unit. The method according to any one of claims 1 to 6, A circuit for cooling the motor 3, the two oil pans 5, 6 and the bearings 7, 9, which first comprises the motor 3, the oil pans 5, 6 and the bearing 7. , 9) and then to ensure a thermal gradient between the compression stage casing 13 Pumping unit. An inlet flange joint 16 and an outlet flange joint 18 which comprise a compression stage casing 13 having a gas inlet 15 and a gas outlet 17, respectively located at the gas inlet 15 and the gas outlet 17. And a heating device for heating a single stage vacuum pump, comprising: a heating means for heating the vacuum pump, The gas inlet 15 perpendicular to the directions 19, 21 of the gases to be pumped in planes parallel to each other to heat the compression stage casing 13 by heat diffusion between the gas inlet 15 and the gas outlet 17. ) And two heating resistors 24, 29 arranged at the gas outlet 17, respectively. Heating device. The method of claim 8, The at least one heating resistor 24, 29 has a circular arc strip shape. Heating device. The method of claim 9, At least one heating resistor 24, 29 is provided with a plurality of holes 31 so that it can be attached to the inlet flange joint 16 and / or the outlet flange joint 18 of the pumping unit 1. Heating device.

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