JP2010084771A - Reciprocating compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reciprocating compressor performing electrically operated backflow control to generate a high operating force with high motion dynamics similarly to hydraulic backflow control while improving known requirements for reducing a structural size and current consumption. <P>SOLUTION: A lift device 3 includes an electric motor 5 as a drive mechanism, and a driven member 6 of the electric motor 5 includes a guide track 7 obliquely extending in the rotating direction for a low-friction rolling member 8. Meanwhile, the rolling member 8 is cooperated in conjunction with the other guide 9 which is provided at a rotation-prevented lift member 10 coupled to a lift gripper 2 while obliquely extending. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reciprocating compressor that performs discharge amount control, and includes a lift gripper disposed on at least one automatic suction valve of the compressor, and the lift gripper is electrically operated. Thus, it relates to a type in which at least one sealing member of the suction valve is opened over a part of the working cycle of the compressor. Furthermore, the present invention relates to a method for controlling the discharge amount in this type of reciprocating compressor.

  "Backflow control" is often performed for the discharge rate control of a reciprocating compressor which preferably operates at a constant rotational speed. In the backflow control, at least one intake valve for each cylinder is opened over a predetermined range of the compression stroke. The pressing force or flow force of the gas pushed back through the opened suction valve can only close the closing member of each suction valve after overcoming a predetermined part of the piston stroke. This is because the closing member is loaded from the opposite side with a counter force set in accordance with a desired discharge amount reduction. The greater this counteracting force, the closer each intake valve closes than during the compression stroke. Thereby, the discharge amount decreases. If a certain counter force is set too large, none of the suction valves will be closed at all. Therefore, the lower limit of the control range in this type of compressor control is derived from the idle operation of the compressor in the meantime and this. In order to avoid all problems and must be limited. In this discharge amount control, the load device for the intake valve to be opened is easily urged in advance either hydraulically or pneumatically, and the change in the appropriate urging pressure affects the discharge amount. Configurations that can be effected are known.

  Further, for example, in reverse flow control for a reciprocating compressor known from EP 694 493 A1, a hydraulic control cylinder that can be loaded and released by a pressure medium periodically during a stroke cycle via a control member is opened in the stroke direction. Acting on the closing member of the suction valve to be operated. As a result, the lift force due to the hydraulic pressure is suddenly reduced at a predetermined piston angle, thereby introducing a reliable and quick closing of the intake valve. A similar discharge rate control known from EP 1400 552 A1 with pneumatic operation has the advantage that the operating pressure can be derived directly by the reciprocating compressor itself. However, due to the relatively high compressibility of the gas to be compressed, the conditions to be precisely defined with respect to the volume to be evacuated and the evacuation time must be observed.

  Furthermore, reciprocating compressors that perform electrically operated backflow control of the type described at the beginning have also been known for a long time. For example, in DE 1251121A or DE 849739B and similar publications, some already dating back to the 30s of the last century, the lift gripper acting on the seal member of the suction valve is moved via an electromagnet attached to the valve cap. The electromagnet is periodically excited by, for example, a collector that rotates in synchronization with the crankshaft of the compressor. A large electromagnet with a correspondingly large current consumption is required, based in part on the extremely large countercurrent forces acting on the sealing element of the suction valve.

EP694946A1 EP1400692A1 DE1251121A DE849739B

  The object of the present invention is to provide a high operating force similar to that of the hydraulic back flow control in a high motion dynamic characteristic, despite the improvement of the known requirements regarding the reduction of the configuration size and current consumption. It is an object to provide a reciprocating compressor with electrically operated back flow control.

  In order to solve the above-described problems, in the reciprocating compressor according to the present invention, which performs discharge amount control, the lift device has an electric motor as a drive device, and the driven member of the electric motor has a rotation direction. A guide track extending in a slanted manner for a low friction rolling member, which is on the other hand provided on a detented lift member coupled to the lift gripper Cooperated with the extended counterpart guide.

  An advantageous embodiment is the invention according to the dependent claims.

  Preferably, the driven member of the electric motor forms a ball circulation type spindle driving device together with the lift member that is prevented from rotating and the rolling member that is disposed between the driven member and the lift member.

  Preferably, the driven member of the electric motor is allowed to rotate only at a limited angle together with the lift member that is prevented from rotating and the rolling member that is disposed between the driven member and the lift member. A swash plate cam driving device is formed.

  Preferably, the electric motor is formed as a brushless DC motor having a permanent magnet mounted on the surface and banded.

  Preferably, the electric motor has a hollow shaft rotor, and a nut of the ball circulation type spindle driving device is incorporated in the hollow shaft rotor.

  Preferably, the hollow shaft rotor has a diameter in the range of 30-50 mm, and the pitch of the ball circulating spindle drive is advantageously in the range of 6-12 mm.

  Preferably, the elements of the rolling pair are at least partly made of ceramic.

  Preferably, an additional spring member is provided for at least one of acceleration and braking of the movement of the lift device.

  Preferably, the electrical control device of the electric motor is provided with a circuit element for braking accompanying power generation and storing and reusing electrical energy regenerated from the braking.

  Preferably, the electric control device for the electric motor is provided with a circuit element for adapting the opening force of the lift device to the countercurrent force acting each time by controlling the energization of the electric motor. .

  In order to solve the above problems, in the method for controlling the discharge amount in the reciprocating compressor according to the present invention, the braking energy that must be applied to brake the drive device of the lift device is supplied to the electric motor. The current generated during braking with power generation and generated during braking is stored and reused.

  An advantageous embodiment is the invention according to the dependent claims.

  Preferably, the opening force of the lift device is adapted to the countercurrent force acting each time by controlling the energization of the electric motor.

  With such a configuration, a relatively small electric motor can be used, and the rotational motion of the electric motor can be easily achieved through a rolling pair extending in an inclined manner, with high operating force and high motion dynamic characteristics. The required opening force or opening movement acting on the lift gripper can be converted.

  It is particularly advantageous that the driven member of the electric motor is a ball circulation type spindle driving device together with the lift member that is prevented from rotating and the rolling member that is disposed between the driven member and the lift member. This is an embodiment of the present invention. This type of drive is known and used in various ways as a nearly friction-free linear drive, resulting in a rotational speed limited only by the length and pitch of the rotation of the electric motor. It is possible to have a relatively wide range of influences on operating force and dynamic characteristics through conversion to linear motion.

  Although it is structurally simpler but lacks in a wide variety of variations, the driven member of the electric motor includes the lift member that is prevented from rotating and the rolling member that is disposed between the driven member and the lift member. It is another advantageous embodiment of the present invention in which a swash plate cam drive device that allows only a limited angle of rotation is formed with the moving member. As a result, only a part of one rotation of the electric motor can be used for the occurrence of linear motion, but with much smaller structural effort and higher operating force instead of a ball as a rolling element There is a possibility that a columnar shape, a truncated cone shape, or a barrel shape that is meaningful to the above will be used.

  In another advantageous form of the invention, the electric motor is formed as a brushless DC motor with a permanent magnet mounted on the surface and banded. This allows high dynamic characteristics in a small structural form. Particularly advantageous in this connection is that the electric motor is formed with a hollow shaft rotor in which the nut of the ball circulating spindle drive is incorporated. This reduces the overall inertia of the rotor or rotary drive.

  In another advantageous form, the hollow shaft rotor has a diameter in the range of 30-50 mm, and the pitch of the ball circulating spindle drive is preferably in the range of 6-12 mm; It has been found to be particularly advantageous for the normal field of use of this type of backflow control in the present invention. This results in a high dynamic characteristic of the lift control as well as a particularly well adapted relationship for high operating forces.

  In another form of the invention, the elements of the rolling pair are at least partially made of ceramic. The extremely high acceleration moments and braking moments that occur in certain situations in electric motor-type drive devices prevent the rolling members from being directly driven by the movement of their guide tracks, causing slip on the bearing track, and thus In some cases, wear may occur. This problem can be solved by the use of ceramic or hybrid bearing devices with ceramic rolling elements and suitable preloads.

  Additional spring members may be provided for at least one of acceleration and braking of the movement of the lift device. This makes it possible to reduce the load on the electric motor type drive device when properly adjusted.

  In another advantageous form of the invention, the electric control device for the electric motor is provided with circuit elements for braking with power generation and for storing and reusing electrical energy regenerated from the braking. It may be. Storage can advantageously take place in a capacitor. The generated and stored current can be used for the next operation process in the same valve or another intake valve of the compressor. As a result, the energy consumption for operating the lift gripper is greatly reduced, and at the same time, the exhaust heat generated in the system is reduced. This reduces the thermal load and avoids cooling problems in the lift device.

  Again, another advantageous form of the invention is useful in which the current lifting force is adapted to the course of the backflow force in order to reduce the unnecessary temperature rise of the lifting device. During the opening of the intake valve, the level of the backflow force depends on the current piston speed known or detectable, for example via a crank angle sensor. The energization of the motor that generates the required opening force can be adapted accordingly.

  The present invention will be described in detail below based on the embodiments schematically shown in the drawings.

It is sectional drawing of the area | region of the suction valve of the reciprocating compressor which performs discharge amount control which concerns on this invention. FIG. 3 is a partial schematic cross-sectional view of an alternative form of an electrically operated lift device for a reciprocating compressor performing discharge rate control according to the present invention. FIG. 5 is a detail view of another alternative form of drive device for a lift device for this type of compressor.

  As shown in FIG. 1, a reciprocating compressor or a reciprocating piston compressor, not shown, has a lift gripper 2 disposed on an automatic intake valve 1 of the compressor. The lift gripper 2 opens two ring-shaped seal members 4 of the suction valve 1 over a controllable part of the compressor work cycle by means of an electrically operated lift device 3. The lift device 3 has an electric motor 5 as a drive device for this purpose. A driven member 6 (formed as a central shaft in the present embodiment) of the electric motor 5 is a guide track 7 for the low-friction rolling member 8 extending in a tilted direction (this embodiment). Is formed as a spiral groove extending so as to surround. On the other hand, the rolling member 8 cooperates with a counter-side guide 9 provided on the lift member 10 that is prevented from rotating and extending at an angle. The lift member 10 is coupled to the lift gripper 2.

  As soon as the electric motor 5 is energized, the driven member 6 of the electric motor 5 rotates. The driven member 6, together with the lift member 10 that is prevented from rotating and the rolling member 8 disposed between the driven member 6 and the lift member 10, is a ball screw type ball circulation type in the present embodiment. A spindle drive (Kugelumlaufspindel-Antrieb) is formed. Thereby, the lift member 10 or the operation plunger 11 of the lift member 10 moves upward or downward as viewed in FIG. Thereby, the lift gripper 2 also moves upwards or downwards and interferes with the otherwise free movement of the seal member 4. Thereby, the sealing member 4 is opened over a controllable part of the compression stroke of the compressor against an automatic operation that would otherwise be performed purely through the pressure ratio before and after the intake valve 1. obtain. This permits, in a known manner, control of the discharge rate of a compressor that operates at a constant rotational speed via “reverse flow control”.

  As shown in FIG. 2, the electric motor 5, which is preferably configured as a brushless DC motor having a permanent magnet bandaged permanent magnet 12 attached to the surface, includes a hollow shaft rotor 13 as a driven member 6. Have as. A nut 14 of a ball circulation type spindle driving device is incorporated in the hollow shaft rotor 13. The hollow shaft rotor 13 preferably has a diameter in the range of about 30-50 mm. The pitch of the ball circulation type spindle drive formed by the nut 14, the rolling member 8 and the lift member 10 which is prevented from rotating is preferably in the range of 6 to 12 mm. The hollow shaft rotor 13 is supported by a stator housing 15 via a bearing 16. The stator that cooperates with the banded permanent magnet 12 is designated 17.

  As shown in FIG. 3, the driven member 6 of the electric motor 5 is restricted in combination with the lift member 10 that is prevented from rotating and the rolling member 8 that is disposed between the driven member 6 and the lift member 10. A swash plate cam drive with an inclined ramp is allowed, which only allows rotation of the specified angle. This also makes it possible to use, for example, a columnar, frustoconical or barrel-shaped rolling member 8. The columnar, frustoconical or barrel-shaped rolling member 8 can transmit a larger axial force.

  The rolling pair elements 6, 7, 8, 9, 10 of the ball circulation type spindle driving device or the swash plate cam driving device may be at least partially made of ceramic. This, combined with a suitable preloading of the drive device, avoids the risk of sliding of the rolling element 8 during highly dynamic operation and thus damage to the rolling element guide resulting therefrom.

  For acceleration and / or braking of the movement of the lifting device 2, an additional spring member 18, as shown here only schematically, may be provided.

  As shown schematically only in FIG. 1, the electrical control device 19 of the electric motor 5 includes a circuit element 20 for braking with power generation and for storing and reusing electrical energy regenerated from the braking. May be provided. This avoids unnecessary temperature rise of the lifting device or the need for additional cooling. Furthermore, the control device 19 may be provided with another circuit element 21 for controlling the energization of the electric motor 5 to adapt the opening force of the lift device 3 to the backflow force acting each time. This also helps to reduce unnecessary heat loss.

DESCRIPTION OF SYMBOLS 1 Suction valve 2 Lift gripper 3 Lift apparatus 4 Seal member 5 Electric motor 6 Driven member 7 Guide track 8 Rolling member 9 Opposite side guide 10 Lift member 11 Operating plunger 12 Permanent magnet 13 Hollow shaft rotor 14 Nut 15 Stator housing 16 Bearing 17 Stator 18 Spring member 19 Control device 20 Circuit element 21 Circuit element

Claims (12)

  A reciprocating compressor for controlling a discharge amount, comprising a lift gripper (2) disposed on at least one automatic suction valve (1) of the compressor, wherein the lift gripper (2) is electrically In the type in which at least one seal member (4) of the suction valve (1) is opened over a part of the working cycle of the compressor by the operated lift device (3), the lift device (3) An electric motor (5) is provided as a driving device, and a driven member (6) of the electric motor (5) extends along a guide track (7) extending in a rotating direction with a low friction rolling member (8). ) And the rolling member (8), on the other hand, is provided on a non-rotating lift member (10) which is coupled to the lift gripper (2) and extends in a tilting manner. It is characterized by cooperating with (9) Reciprocating compressors.   The driven member (6) of the electric motor (5) has the lift member (10) which is prevented from rotating, and the rolling member disposed between the driven member (6) and the lift member (10). The compressor according to claim 1, which forms a ball circulation type spindle driving device together with (8).   The driven member (6) of the electric motor (5) has the lift member (10) which is prevented from rotating, and the rolling member disposed between the driven member (6) and the lift member (10). The compressor according to claim 1, together with (8), forming a swash plate cam drive device that permits only a limited angle of rotation.   The compressor according to any one of claims 1 to 3, wherein the electric motor (5) is formed as a brushless DC motor with a permanent magnet (12) mounted on the surface and banded.   The said electric motor (5) has a hollow shaft rotor (13), The nut (14) of the said ball | bowl circulation type spindle drive device is integrated in this hollow shaft rotor (13). The compressor according to claim 4, wherein 2 or claim 2 is cited.   6. The hollow shaft rotor (13) has a diameter in the range of 30-50 mm, and the pitch of the ball circulating spindle drive is preferably in the range of 6-12 mm. Compressor.   Compressor according to any one of the preceding claims, wherein the elements (6-10) of the rolling pair are at least partly made of ceramic.   The compressor according to any one of the preceding claims, wherein an additional spring member (18) is provided for at least one of acceleration and braking of the movement of the lifting device (3).   The electric control device (19) of the electric motor (5) is provided with a circuit element (20) for braking accompanied by power generation and for storing and reusing electrical energy regenerated from the braking. The compressor according to any one of claims 1 to 8.   A circuit for adapting the opening force of the lift device to the countercurrent force acting each time by controlling the energization of the electric motor (5) to the electric control device (19) of the electric motor (5). The compressor according to any one of claims 1 to 9, wherein an element (21) is provided.   11. A method for controlling a discharge amount in a reciprocating compressor according to claim 1, wherein braking energy that must be applied to brake the drive device of the lift device (3) is applied to the electric motor. (5) A method for controlling a discharge amount in a reciprocating compressor, characterized by storing and reusing a current generated by braking accompanied by power generation and generated during braking.   12. Method according to claim 11, wherein the opening force of the lifting device (3) is adapted to the countercurrent force acting each time by controlling the energization of the electric motor (5).

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