CN101813197A

CN101813197A - Flow control valve

Info

Publication number: CN101813197A
Application number: CN200910009222A
Authority: CN
Inventors: 张明亮
Original assignee: Siemens Ltd China
Current assignee: Siemens Ltd China
Priority date: 2009-02-25
Filing date: 2009-02-25
Publication date: 2010-08-25

Abstract

The invention provides a flow control valve, which can be used for flow control in an exhaust gas recirculation pipeline of an internal combustion engine. The flow control valve is provided with a pipe communicating the pipeline, wherein a rotary plate for blocking the pipe is arranged along the vertical direction of the pipe; at least one opening is reserved on the rotary plate; the rotary plate can rotate to the position where the opening and the pipe are superposed; the diameter of the opening is not greater than the outer diameter of the pipe; and a drive mechanism can drive the rotary plate to rotate around the axis of a rotating shaft and the drive mechanism can be a piezoelectric drive mechanism. The flow control valve has the advantages of compact and simple structure, smart size, low energy consumption, low noise and easy and accurate flow adjustment.

Description

Flow control valve

Technical Field

The present invention relates to a flow control valve, and in particular to a flow control valve which can be used in an exhaust gas recirculation line of an internal combustion engine.

Background

In order to reduce harmful gas emissions, an Exhaust Gas Recirculation (EGR) system is generally provided in an internal combustion engine, which recirculates a portion of exhaust gas from an exhaust passage to an intake passage to reduce the emissions of the engine. The EGR system is effective to reduce the combustion temperature of the engine, thereby effectively reducing the content of toxic substances such as nitrogen oxides in exhaust gas.

The EGR system mainly includes an exhaust gas recirculation line for guiding recirculation of exhaust gas of the exhaust passage into the intake passage, and an exhaust gas recirculation valve. An exhaust gas recirculation valve is typically disposed in the recirculation line for controlling the flow of recirculated exhaust gas. A typical egr valve is a valve that is driven by the movement of a valve stem that is driven by a drive means. Common driving methods are: electromagnetic drive, stepper motor drive, dc motor drive, torque motor drive, and the like. However, the existing egr valve has a complex structure, the electromagnetic drive is susceptible to magnetic field interference, the stepping motor drive requires more magnetic poles, and the dc motor drive requires a gearbox to reduce the speed and increase the torque.

US 4473056 a discloses an electric motor driven exhaust gas recirculation valve. The valve body is controlled and operated by a motor. The positioning screw and the steel ball help the rotation of the output shaft of the motor to be converted into the vertical motion of the valve rod, and the structure of the valve rod is complex. US 4840350 a discloses an exhaust gas recirculation valve driven by a torque motor which, although eliminating the lead screw and providing a high flow control accuracy, has its own disadvantages of being inefficient and costly.

A piezoelectric motor is a motor that has appeared in the seventies of the twentieth century and is generally composed of a rotor, a stator, a driving and controlling means. The piezoelectric motor generally uses a piezoelectric sheet and an elastic metal as a stator, applies a high-frequency alternating voltage to the piezoelectric sheet to excite the piezoelectric sheet, and utilizes the inverse piezoelectric effect of the piezoelectric sheet to make the piezoelectric sheet generate alternate periodic stretching deformation, and the elastic metal is linked to generate vibration, so that a rotor in contact with the piezoelectric sheet moves under the action of friction force. The working principle of the piezoelectric motor can be found in "theory and experimental research of rotary traveling wave ultrasonic motor" (the full-text database of the Chinese excellent doctor's academic papers (master), the author Zhao Bing, 2006, 10, 11, 15-20 pages).

Disclosure of Invention

The technical problem to be solved by the invention is to provide a flow control valve to overcome the defects of electromagnetic drive, stepping motor drive, direct current motor drive, torque motor drive and the like.

The invention provides a flow control valve, which is simple in structure, easy to operate and control and high in control precision.

Another specific technical problem to be solved by the present invention is to provide a flow control valve which is not interfered by a magnetic field, has a compact and simple structure, a small volume, is easy to precisely adjust the flow rate, and has a low cost.

More specifically, in one form of the invention, the operating principle of a piezoelectric motor is utilized to provide a drive mechanism for a flow control valve that can be used to control the flow of fluid in a conduit.

In order to solve the above technical problem, in one form of the present invention, there is provided a flow control valve having a pipe through which a fluid passes, wherein a rotary piece for cutting off the pipe is provided in a direction perpendicular to the pipe, the rotary piece having at least one opening, the rotary piece being rotatable to a position at which the opening coincides with the pipe, and the opening having a diameter not larger than an outer diameter of the pipe.

Preferably, the rotary vane is in sealing contact with the duct wall of the duct.

Preferably, the rotary piece and the pipe are hermetically disposed in a housing, and both ends of the pipe protrude outside the housing.

Preferably, the rotating piece can rotate around the axis of a rotating shaft under the drive of a driving mechanism.

Preferably, the driving mechanism includes a stator, at least one piezoelectric device disposed on one of the stator and the rotor, and at least one sheet of friction material compressed between the stator and the rotor by an elastic member.

Preferably, the stator is a housing supporting and accommodating the rotary piece and the duct, and both ends of the duct protrude to the outside of the housing.

Preferably, the elastic member is disposed around a rotation shaft of the rotation piece and presses the rotation piece toward the stator in an axial direction of the rotation shaft.

Preferably, the rotating plate is formed by two opposite fan-shaped parts, the opening is formed in the first fan-shaped part, and the second fan-shaped part is tightly pressed on the friction material plate.

Preferably, the piezoelectric device comprises a piezoelectric sheet and a control circuit.

Preferably, a boss is provided on one of the rotor plate and the stator, the boss being in contact with the friction material plate.

Preferably, the friction material sheet is disposed on the stator, and the piezoelectric device is disposed on the rotating sheet.

In another form of the present invention there is provided a flow control valve for flow control in an exhaust gas recirculation conduit of an internal combustion engine, the flow control valve having a conduit communicating with said conduit, wherein a rotatable plate is provided in a direction perpendicular to said conduit to intercept said conduit, said rotatable plate having at least one aperture therein, said rotatable plate being rotatable to a position in which said aperture coincides with the conduit, said aperture having a diameter no greater than the external diameter of said conduit.

Preferably, the rotating plate is driven by a driving mechanism to rotate around the axis of a rotating shaft, the driving mechanism comprises a stator, at least one piezoelectric device and at least one friction material sheet, the piezoelectric device is arranged on one of the stator and the rotating plate, and the friction material sheet is tightly pressed between the stator and the rotating plate through an elastic piece.

In the present invention, the driving mechanism of the flow control valve can be provided based on the principle of the piezo motor, and thus has advantages of the piezo motor, specifically:

the rotating sheet in the invention is not only a rotor of the piezoelectric driving mechanism, but also a control sheet for controlling the flow of the valve. The flow rate of exhaust gas in the duct is determined by the overlapping area of the openings in the rotor plate and the duct. Because the rotary piece is driven by high-frequency small-amplitude vibration excited by the piezoelectric thin sheet, the flow rate of exhaust gas recirculation can be accurately controlled.

Due to the inherently high torque-to-speed ratio of the piezoelectric drive, the flow control valve of the present invention is able to provide sufficient torque without the need for mechanical components such as a gearbox. The piezoelectric driving has a larger output torque at a low rotating speed, and can directly drive a load, and generally, if a common electromagnetic motor has the characteristic of large output torque at the low rotating speed, a gear speed change mechanism is usually added to reduce the rotating speed; the piezoelectric driving can directly drive the load without the speed reducing mechanism, so that the weight and the occupied volume of the speed reducing mechanism can be reduced, and the problems of vibration, impact, noise and the like caused by a gear speed changing mechanism can be avoided.

The flow control valve is simpler and more compact in structure. In contrast to piezoelectric motors, the rotor of the present invention rotates only in a sector area, rather than continuously as does the rotor of a piezoelectric motor. Piezoelectric motors typically have a piezoelectric device on the stator, and brushes may be avoided. In the invention, the piezoelectric device can be arranged on the stator or the rotating sheet, and the use of electric brushes can be avoided, thereby improving the reliability of the flow control valve.

In a general electromagnetic motor, the holding torque is small, and after the power is cut off, the motor does not stop immediately because the inertial force is larger than the holding torque. The flow control valve of the present invention is driven by traveling wave frictional coupling between the rotor plate and the stator. The rotating plate of the valve of the present invention can maintain a precise position without consuming additional energy due to the large holding torque provided by the friction.

The flow control valve adopts piezoelectric drive, and is free from magnetic field interference and low in noise compared with the existing modes of electromagnetic drive, direct current motor drive and the like.

Drawings

The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention. Wherein,

FIG. 1 is a schematic cross-sectional view of a flow control valve according to an embodiment of the present invention;

FIG. 2a is a schematic view of a rotating plate opening fully coincident with a conduit in accordance with an embodiment of the present invention;

FIG. 2b is a schematic view of the aperture of the rotating plate coinciding with the conduit portion in accordance with one embodiment of the present invention;

figure 2c is a schematic view of the aperture of the rotor plate not coinciding with the pipe in accordance with one embodiment of the present invention.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings. Wherein like parts are given like reference numerals.

FIG. 1 is a schematic cross-sectional view of a flow control valve according to an embodiment of the present invention. As shown in the drawings, the flow control valve 1 of the present embodiment has a pipe 100 for passing a fluid therethrough, a rotary piece 107 provided along a vertical direction of the pipe 100 to intercept the pipe 100, and at least one opening 109 provided in the rotary piece 107 to be rotatable to coincide with the pipe 100, wherein a diameter of the opening 109 is not larger than an outer diameter of the pipe 100.

As can be seen in the figures, the duct 100 is in fact made up of two parts separated by a rotating tab 107, the tab 107 being interposed vertically between the two parts. To prevent fluid from leaking out of the interface between the conduit 100 and the rotary plate 107, the rotary plate 107 is in sealing contact with the conduit wall of the conduit 100. Depending on the nature of the fluid, a sealing device (not shown) may be provided at the interface between the conduit 100 and the rotary plate 107, for example a rubber sealing boot may be provided on the conduit wall. In addition, in order to protect the internal components of the flow control valve 1, the rotary piece 107 and the pipe 100 may be hermetically disposed in a housing 105, and both ends of the pipe 100 may extend outside the housing 105 to be connected to a pipe of a fluid to be controlled, such as an exhaust gas recirculation pipe. The housing 105 may also provide some sealing in the event of a leak at the interface between the conduit 100 and the rotating plate 107.

The rotating piece 107 can be rotated around the axis of a rotating shaft 102 by a driving mechanism 2. Wherein the rotary shaft 102 is supported by the bearing 101 on the housing 105, and the rotary shaft 102 is rotatable about its axis together with the rotary piece 107. Of course, the rotating piece 107 may be mounted on the rotating shaft 102 through a bearing, the rotating shaft 102 is fixedly mounted relative to the housing 105, the rotating piece 107 can rotate around the axis of the rotating shaft 102, and the rotating shaft 102 is kept stationary relative to the rotating piece 107.

The driving mechanism 2 may be a manual driving mechanism, a mechanical transmission mechanism, a stepping motor, or a driving mechanism directly driving the rotary piece 107, such as a piezoelectric driving mechanism shown in fig. 1, which is mounted on the rotary shaft 102.

As shown in fig. 1, the drive mechanism 2 includes a housing 105 as a stator 105', at least one piezoelectric device 12 disposed on a rotor 107, and at least one sheet 108 of friction material. Wherein a sheet 108 of friction material is provided on the housing 105 and is compressed between the housing 105 and the rotary piece 107 by an elastic member 103. The elastic member 103 is disposed around the rotating shaft 102 of the rotating piece 107, and presses the rotating piece 107 toward the housing 105 in the axial direction of the rotating shaft 102 and against the friction material piece 108.

The rotating sheet 107 is provided with a boss on the surface connected with the friction material sheet 108, and the arrangement of the boss reduces the contact area with the friction material sheet 108 on one hand, can also eliminate the contact between the rotating sheet 107 and the shell 105 and is more beneficial to the relative motion between the rotating sheet 107 and the pipeline 100; on the other hand, the arrangement of the bosses can also reduce the rigidity of the rotating piece 107, which is beneficial for the rotating piece 107 to generate elastic vibration under the excitation of the piezoelectric device 12. Of course, it will be understood by those skilled in the art that the above-described bosses may also be provided on the housing 105, i.e., a semi-annular boss covered with a sheet of friction material may be provided on the housing 105.

It is specifically noted that in one embodiment of the present invention, the stator 105' may be a separate component (not shown in fig. 1) having a surface in close contact with the surface of the rotor plate 107. In the preferred embodiment of the present invention shown in fig. 1, the separate stator is omitted, and the housing 105 replaces the separate stator to realize the function of the stator, so that the number of parts of the separate stator can be reduced, and the structure of the flow control valve 1 is simpler and the cost is lower. For convenience of description, the housing 105 mentioned in the following description functions in the same manner as the stator 105'.

The piezoelectric device 12 includes a piezoelectric sheet 106 and a control circuit 104. In one embodiment of the present invention, the piezoelectric sheet 106 is made of a piezoelectric ceramic, such as lead zirconate titanate ceramic or the like. Of course, other piezoelectric materials capable of exciting the rotor to vibrate to rotate the rotor may be used. The control circuit 104 is configured to apply a high-frequency voltage to the piezoelectric sheet 106 to excite the piezoelectric sheet to vibrate, thereby generating a driving force.

Referring to fig. 2a-2c, in a preferred embodiment of the invention, the rotary piece 107 is designed in the shape of two opposing segments. Wherein a first sector is provided with a piezoelectric foil 106 and an opposite second sector is provided with an opening 109. It will be appreciated by those skilled in the art that the rotary plate 107 may be entirely disc-shaped. Of course, the above dual fan-shaped approach may save material and, more importantly, reduce the mass of the rotary piece 107, thereby reducing the inertia of the rotary piece 107 to facilitate more precise control of the position of the rotary piece 107.

Also, in order to reduce the cost, the friction material pieces 108 may be provided within the rotational angle range of the rotary piece 107, not necessarily in the entire circular ring.

In another embodiment of the invention, the piezoelectric device is disposed on the housing 105 and, correspondingly, a sheet of friction material is disposed on the side of the rotating plate 107 that contacts the housing 105. Of course, similarly, the friction material piece 108 only needs to be provided within the angular range in which the rotary piece 107 rotates, and a boss may be provided on the rotary piece 107 or the housing 105, which is not repeated here.

The operation principle and process of the flow control valve 1 of the present invention will be further described with reference to the accompanying drawings.

See fig. 2a-2 c. The piezoelectric sheet 106 generates electrostrictive effect after being applied with high frequency voltage through the control circuit 104, and causes the piezoelectric sheet 106 to expand and contract, thereby exciting the rotary piece 107 to vibrate, and enabling the rotary piece 107 to rotate around the rotating shaft 102 through the friction resistance effect of the friction material piece 108. The principle of action is similar to that of a piezo motor. In the present invention, the rotary piece 107 is a control piece for controlling the flow rate of the pipe 100 as well as a rotor of the piezoelectric driving mechanism, and the rotary piece 107 is also an elastic piece for generating vibration.

Under the control of the control circuit 104, the flow control valve 1 can make the rotary piece 107 rotate to a state that the opening 109 is completely overlapped with the pipeline 100, at this time, the valve is opened to the maximum, and the fluid flow in the pipeline 100 is the maximum, as shown in fig. 2 a; or may be rotated to a position where the opening 109 partially coincides with the conduit 100, wherein the valve is in a partially open position and the flow of fluid in the conduit 100 is reduced, as shown in fig. 2 b; it is also possible to rotate to a position in which the opening 109 is not coincident with the pipe 100, in which the valve is closed, the pipe 100 is shut off and the flow of fluid is zero. In this way, the opening and closing of the pipe 100, and thus the amount of fluid flow in the pipe 100, can be controlled by varying the overlapping area of the opening 109 and the pipe 100.

If the rotation direction of the rotary piece 107 is changed, only the excitation voltages applied to the two poles of the piezoelectric sheet 106 need to be inverted.

The rotating sheet of the flow control valve does not need to rotate continuously like a piezoelectric motor, but only needs to rotate in a reciprocating manner within a limited angle range, so that the friction material sheet can be arranged only within a required range, the material is saved, and the cost is reduced. More importantly, the electric connection of the piezoelectric thin sheet does not need to adopt an electric brush, and the reliability is high.

In the invention, the driving mechanism of the flow control valve is designed based on the principle of a piezoelectric motor, and the driving mode of the existing exhaust gas recirculation valve is not just replaced by the piezoelectric motor.

The flow control valve of the present invention is able to provide sufficient torque without the need for mechanical components such as a gearbox. The weight and the occupied volume of the speed reducing mechanism can be reduced, and the problems of vibration, impact, noise and the like caused by the gear speed changing mechanism can be avoided. The flow control valve has a simpler and more compact structure, can avoid adopting an electric brush, and improves the reliability.

The flow control valve of the present invention is driven by traveling wave friction coupling between the rotor plate and the stator. Since friction provides a large holding torque, the rotating plate of the valve of the present invention can maintain an accurate position without consuming additional energy, reducing overall energy consumption. Compared with the existing modes of electromagnetic driving, direct current motor driving and the like, the magnetic field interference-free electromagnetic driving device is free from magnetic field interference and low in noise.

The flow control valve can be applied to an exhaust gas recirculation system of an internal combustion engine, is used for controlling the flow of exhaust gas recirculation as the exhaust gas recirculation valve, and has the advantages of high control precision, silence and low energy consumption.

The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. Any equivalent alterations, modifications and combinations can be made by those skilled in the art without departing from the spirit and principles of the invention.

Claims

1. A flow control valve having a conduit (100) for the passage of a fluid, characterised in that a rotatable plate (107) is provided for cutting off the conduit (100) in a direction perpendicular to the conduit (100), the rotatable plate (107) having at least one aperture (109) formed therein, the rotatable plate (107) being rotatable to a position in which the aperture (109) coincides with the conduit (100), the aperture (109) having a diameter which is not greater than the external diameter of the conduit (100).

2. A flow control valve according to claim 1, wherein the rotary plate (107) is in sealing contact with a duct wall of the duct (100).

3. A flow control valve according to claim 1, wherein the rotary plate (107) and the duct (100) are sealingly arranged in a housing (105), the duct (100) extending with both ends outside the housing (105).

4. A flow control valve according to claim 1, wherein the rotary plate (107) is rotatable about the axis of a rotary shaft (102) by a drive mechanism (2).

5. A flow control valve according to claim 4, wherein the drive mechanism (2) comprises a stator (105 '), at least one piezoelectric device (12) and at least one piece (108) of friction material, the piezoelectric device (12) being arranged on one of the stator (105 ') and the rotor (107), the piece (108) of friction material being compressed between the stator (105 ') and the rotor (107) by means of a resilient member (103).

6. The flow control valve according to claim 5, wherein the stator (105') is a housing (105) supporting and accommodating the rotary piece (107) and the pipe (100), and both ends of the pipe (100) protrude to the outside of the housing (105).

7. The flow control valve according to claim 5, wherein the elastic member (103) is provided around a rotation shaft (102) of the rotary piece (107) and presses the rotary piece (107) toward the stator (105') in an axial direction of the rotation shaft (102).

8. A flow control valve according to claim 5, wherein the rotating plate (107) is formed by two opposite sectors, the opening (109) being provided in a first sector and the second sector being pressed against the piece (108) of friction material.

9. A flow control valve according to claim 5, wherein the piezoelectric device (12) comprises a piezoelectric foil (106) and a control circuit (104).

10. A flow control valve according to claim 5, wherein one of the rotor (107) and the stator (105') is provided with a boss which abuts the sheet (108) of friction material.

11. A flow control valve according to claim 5, wherein the sheet (108) of friction material is provided on the stator (105') and the piezoelectric device (12) is provided on the rotor (107).

12. A flow control valve for flow control in an exhaust gas recirculation line of an internal combustion engine, the flow control valve (1) having a conduit (100) communicating with said line, characterized in that a rotatable plate (107) is provided in a direction perpendicular to said conduit (100) to intercept said conduit (100), said rotatable plate (107) being provided with at least one opening (109), said rotatable plate (107) being rotatable to a position in which said opening (109) coincides with said conduit (100), said opening (109) having a diameter not greater than the outer diameter of said conduit (100).

13. A flow control valve according to claim 12, wherein the rotor (107) is rotatable about the axis of a shaft (102) by a drive mechanism (2), the drive mechanism (2) comprising a stator (105 '), at least one piezoelectric device (12) and at least one sheet (18) of friction material, the piezoelectric device (12) being disposed on one of the stator (105 ') and the rotor (107), the sheet (108) of friction material being compressed between the stator (105 ') and the rotor (107) by an elastic member (103).

14. The flow control valve according to claim 13, wherein the stator (105') is a housing (105) supporting and accommodating the rotary piece (107) and the pipe (100), and both ends of the pipe (100) protrude to the outside of the housing (105).

15. The flow control valve according to claim 13, wherein the elastic member (103) is provided around a rotation shaft (102) of the rotary piece (107) and presses the rotary piece (107) toward the stator (105') in an axial direction of the rotation shaft (102).

16. A flow control valve according to claim 13, wherein the rotating plate (107) is formed by two opposite sectors, the opening (109) being provided in a first sector and the second sector being pressed against the piece (108) of friction material.

17. A flow control valve according to claim 13, wherein the piezoelectric device (12) comprises a piezoelectric foil (106) and a control circuit (104).

18. A flow control valve according to claim 13, wherein one of the rotor (107) and the stator (105') is provided with a boss which abuts the sheet (108) of friction material.

19. A flow control valve according to claim 13, wherein the sheet (108) of friction material is provided on the stator (105') and the piezoelectric device (12) is provided on the rotor (107).