DE10104405A1 - Piston machine control process involves making opening of induction valve dependent on pressure difference - Google Patents

Abstract

The control process involves measuring the pressure difference between the stage induction and the internal pressure of the cylinder, and opening the induction valve when the pressure difference reaches a preset magnitude for the first time, and closing it when it reaches a preset magnitude for the last time.

Description

Piston compressors are mostly self-sufficient Valves controlled by gas pressure differences are used.

The main components of these valves are basically the valve seat and catcher, one or more Other locking elements, usually a plate or rings, and damper and spring organs. With regulated suction valves, the valve continues to be lifted off operated gripper.

This not inconsiderable number of parts becomes a periodic lifting movement subjected, and depending on the stroke of the closing elements and the density and pressure of the Gases are dynamically heavily loaded, which leads to restrictions in service life Breaks in the closing, damper and spring elements.

Furthermore, the design of the spring elements must be optimal on one working point be coordinated, but what with fluctuating operating conditions, or by rotation Payment scheme leads to adjustment problems, since there is no way to leg flow of the spring forces in the valves.

In addition, the valves in the delivery quantity control by dynamic pressure or Reverse flow heavily loaded via a lifting gripper.

Disadvantages are the cross sections limited by the stroke, by the geometry of the Valve large damaged areas, the masses of the moving parts, the existing spring forces, as well as the deflection of the gas with automatically operating valves, what ultimately leads to considerable pressure losses.

The invention is therefore based on the object of a device and a method for Control of a piston machine, in particular a compressor or a To create a vacuum pump, which is independent of fluctuating operating conditions conditions and speed changes can be operated, as well as influencing the To improve the delivery quantity so that the aforementioned disadvantages are avoided.

According to the invention, this object is achieved by a device and a method with the Features solved from claims 1 and 2.

Methods according to the prior art are

• 1. EP 0 694 693 B1 known, but it is a suction valve which works automatically depending on the pressure and only for delivery quantity control via a stroke movement of a control piston is influenced on a lifting claw.
• 2. DE 40 02 856 A1 known, the gas exchange valve in a lifting movement offset, and not rotated.
• 3. DE 34 00 970 A1 known, the valve slotted disc depending on Crankshaft is operated.
• 4. DE-OS 19 11 617 known, this method depending on Crankshaft is operated.
• 5. DE 37 10 824 A1 known, the control disc depending on Crankshaft is operated.
• 6. DE 198 27 301 A1 known, the rotary disc in a combustion chamber of an internal combustion engine is rotated by an electric drive device.

The invention relates to a device and a method for controlling a Piston machine with a rotary slide valve, which is independent of the position the crankshaft is actuated by an actuator.

The rotary slide valve contains only one closing element, which is rotatably arranged, and therefore does not require any lifting movement. In addition, the suspension is provided by the Forced control not required. This allows the valve to be operated independently of the Density and the pressure of the gas, changing operating conditions as well as variable Speeds are operated.

Due to the forced control, the large flow cross-sections and the straight flow the gas through the valve results in small pressure drops, which ultimately leads to Reduction of the valve diameter and thus also a reduction in mass can contribute.

In contrast to EP 0 694 693 B1, it is advantageous that there is none in the case of regulated suction valves Lifting gripper is used, and the high actuating forces to overcome the currents force are not required because the opening and closing of the valves at one Pressure equilibrium is carried out.

This advantage of opening and closing with a pressure balance is transferred also on uncontrolled suction valves and pressure valves, which is ultimately in one reflects low energy expenditure.

By positively controlling the valves on one derived from the process Pressure equilibrium, the system is governed by the detection of the rotation moments of the valves to be controlled adaptively, whatever to optimal efficiencies leads even with fluctuating operating conditions of the piston machine.

Further features and advantages of the invention result from the following description Exercise of a preferred embodiment with reference to the accompanying drawings. It shows:

Fig. I shows a 2d section of the device according to the invention

Fig. II Frame 1 pV diagram showing the pressure curves for the acquisition of the differential pressures between Stufensaug- and cylinder pressure, as well as Stufenend- and cylinder pressure.

Fig. II Image 2 is recorded, the pressure curve for the part-load range, wherein the volume is shown reduced.

Fig. 3d III a section of the device according to the invention

This is a new type of valve and a method for the positive control thereof, consisting of a valve seat ( 1 ) which is provided with channels for the gas to flow through, and a rotatable closing member ( 2 ). On the side of the valve seat ( 1 ) to be sealed, the channels are provided with seat strips which, on the one hand, result in better tightness due to a higher surface pressure between the seat and the closing element, and on the other hand contribute to the fact that the closing element ( 2 ) rotates Residues from the gas can be wiped off the seat rails. For this purpose, it is possible to treat the closing element ( 2 ), which is not subject to a lifting movement in the sense of a classic compressor valve, and the seat strips to give a high degree of wear resistance and chemical resistance to abrasive and aggressive gases.

Furthermore, the channels are conical, which narrow to the seat strips. As a result, the gas can flow through the channel without deflection at the closing element, which would not be possible with a cylindrical shape of the channel.

A drive shaft ( 11 ), which is attached in the center of the closing element ( 2 ) via a sliding bush ( 4 ) and is guided through a ceramic bearing ( 5 ) in the valve seat ( 1 ), is via a lower elastomer coupling ( 10 ) to damp the stepwise or pivoting movement, actuated by an actuator ( 13 ).

The actuator ( 13 ), consisting of at least one control cylinder ( 14 ) for generating the rotary movement, is preferably controlled by a 2/2 piezoelectric or 3/2 way valve to achieve a high clock frequency and short switching times in connection with the drive ,

The stage suction and stage end pressure as well as the cylinder interior are measured pressure, which is divided into a suction phase and a compression phase, continuously detected.

The point in time for the suction valve is calculated by a controller for the first time a pressure equilibrium between the stage suction and cylinder pressure established.

This point in time is used to open the suction valve, the torque of the closing element ( 2 ) to be actuated being determined simultaneously by a sensor. Due to the inertia of the valve, however, it is opened with a delay, the pressure difference increasing due to the passage of time, and thus the torque being increased. For the next revolutions of the crankshaft, therefore, the opening time of the suction valve is advanced or postponed by a predetermined time period Δt until the torque reaches its minimum.

At the end of the suction phase, a controller calculates the point in time at which a pressure equilibrium is finally established between the step suction and cylinder pressure. This point in time is used to close the suction valve, at the same time the torque of the closing element ( 2 ) to be actuated is determined by a sensor and the procedure is continued as before.

The same procedure applies to the pressure valve in the compression phase, whereby the pressure equilibrium between the stage end pressure and the internal cylinder pressure and last determined, and the same for opening and closing the pressure valves Procedure as used for the suction valves.

The bottom dead center of the piston (180 ° crank angle for the suction valve) and the top dead center of the piston (360 ° crank angle for the pressure valve) are used.

Furthermore, the valves can be prestressed by a pressure medium via the actuators ( 13 ) in order to open or close with a predetermined torque before reaching the pressure equilibrium.

The delivery quantity control is achieved after the pressure equilibrium has been reached for the last time the suction valve is not closed, but over at least a portion of the ver sealing stroke kept open, the intake quantity being pushed out again does not correspond to the delivery volume to be compressed.

Only then is the suction valve closed and the compression phase can start with use a reduced gas volume.

In order to achieve a defined starting position of the actuator ( 13 ), the control piston ( 15 ) is preferably equipped with a return spring ( 16 ). As a result, the actuator ( 13 ) can be moved into an end position by the return spring ( 16 ) when the system is switched off, as a result of which the suction valve rotates into an open position.

LIST OF REFERENCE NUMBERS

Out

FIG.

I:

1

valve seat

2

closing member

3

center screw

4

bush

5

ceramic bearings

6

Lower pane

7

Upper disc

8th

feather

9

lead nut

10

Lower elastomer coupling

11

drive shaft

12

Upper elastomer coupling

13

actuator

14

control cylinder

15

spool

16

Reset spring
Out

FIG.

II:
p _s

Stufensaugdruck
p _d

Stufenenddruck
p _s-cyl

Cylinder internal pressure (suction side)
p _d-cyl

In-cylinder pressure (pressure side)
Δp _s1-cyl

first pressure equilibrium between internal cylinder pressure (suction side) and step suction pressure
Δp _s2-cyl

last pressure equilibrium between cylinder pressure (suction side) and step suction pressure
Δp _d1-cyl

first pressure equilibrium between internal cylinder pressure (pressure side) and final stage pressure
Δp _d2-cyl

last pressure equilibrium between internal cylinder pressure (pressure side) and final stage pressure

Claims (10)

1. Device and method for controlling a piston engine, with a rotary slide valve for the inlet of a gas into the working space of the piston engine, which is actuated independently of the position of the crankshaft of the piston engine by an actuator ( 13 ), characterized in that during the suction phase the differential pressure between the stage suction (p _s ) and the _internal cylinder pressure (p _s-cyl ) is measured and the suction valve is opened when the differential _pressure (Δp _s1-cyl ) reaches a predetermined value for the first time, and is closed when the differential _pressure ( Δp _s2-cyl ) has reached a predetermined value for the last time. 2. Device and method for controlling a piston machine, with a rotary slide valve for the outlet of a gas from the working space of the piston machine, which is operated independently of the position of the crankshaft of the piston machine by an actuator ( 13 ), characterized in that during the compression phase the differential pressure between the stage end (p _d ) and the cylinder internal pressure (p _d-cyl ) is measured and the pressure valve is opened when the differential pressure (Δp _d1-cyl ) reaches a predetermined value for the first time, and is closed when the differential pressure (Δp _d2-cyl ) has reached a predetermined value for the last time. 3. Device and method for the continuous control and regulation of a piston engine according to claim 1 and 2, characterized in that when the pressure equilibrium is first reached between the stage suction (p _s ) and the cylinder pressure (p _s-cyl ) and between the stage end (p _d ) and _internal cylinder pressure (p _d-cyl ) the torque of the suction or pressure valve to be actuated is determined by a measuring sensor, and the time for opening the respective valve is advanced or postponed by a time period Δt until the torque reaches its minimum reached, and the optimal efficiency of the piston machine is reached. 4. Device and method for the continuous control and regulation of a piston engine according to claim 1 and 2, characterized in that the last time the pressure equilibrium between the stage suction (p _s ) and the cylinder pressure (p _s-cyl ) and between the stage end ( p _d ) and _internal cylinder pressure (p _d-cyl ), the torque of the suction or pressure valve to be actuated is determined via a measuring sensor, and the time for closing the respective valve is advanced or postponed by a time period Δt until the torque reaches its minimum , and the optimum efficiency of the piston machine is reached. 5. A method for controlling a piston machine according to claims 1 to 4, characterized in that the valves via the actuators ( 13 ) are biased by a pressure medium to a predetermined torque to open or close the valves before reaching the pressure equilibrium. 6. The method according to claim 1 and 2 for backflow control of a piston machine by keeping at least one suction valve open over at least one part area of the compression stroke, characterized in that at the end of each the suction valve by means of a predetermined value closed, and the compression process is initiated. 7. The method according to claim 1 and 2 for the intake control of a Kolbenma machine by closing at least one suction valve over at least a portion of the intake stroke, characterized in that at the end of each by a predetermined value open part of the suction valve closed, and the Intake process is interrupted. 8. Device and method for moving a closing member ( 2 ) of a rotary slide valve according to claims 1 to 7, characterized in that the actuator ( 13 ) from a drive shaft ( 11 ) which is provided with at least two segmented gears, and from at least two Control cylinders ( 14 ), which transmits a rotary or swivel movement to the closing element ( 2 ) of the rotary slide valve by simultaneous or mutual control. The pistons ( 15 ) of the control cylinder ( 14 ) are biased by return springs ( 16 ) so that when the system is switched off there is a defined starting position, and as a result the suction valve basically turns to an open position. 9. valve with a rotatable closing member ( 2 ) for controlling a piston machine according to claims 1 to 8, characterized in that the valve seat ( 1 ) is provided with channels for the flow of gas, which are provided on the side to be sealed with seat strips, the channels being cylindrical or conical, and tapering to the seat strips when conical. A given play of the closing element ( 2 ) in the axial direction is impaired by a spring ( 8 ). So that the spring ( 8 ) is not subject to wear during the rotational movement, at least two disks ( 6 ) and ( 7 ) made of a wear-resistant, preferably ceramic material are present on the side facing away from the seat strips, of which a lower disk ( 6 ) on the valve seat is fixed. The upper washer ( 7 ), with the Fe ( 8 ), which is located between the upper washer ( 7 ) and a guide nut ( 9 ), is fixed to the guide nut ( 9 ) to be rotated with the closing member ( 2 ) are, whereby the friction during the rotation of the locking member ( 2 ) between the discs ( 6 ) and ( 7 ) is shifted. 10. Device and method according to claims 1 to 9 for control and control of a piston machine, characterized in that the device and the method is preferably on a compressor or a vacuum pump Find application.