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Title:
POSITION ACTUATOR HAVING PNEUMATIC VENTILATION
Document Type and Number:
WIPO Patent Application WO/2018/025072
Kind Code:
A1
Abstract:
A position actuator includes a cylinder housing forming a fluid chamber having a first portion and a second portion, a movable main piston disposed in the cylinder housing between the first portion and the second portion, and a piston rod firmly attached to the main piston and extending through one end of the cylinder housing. The position actuator also includes a ventilation device disposed in the chamber and cooperating with the main piston to ventilate air between either one of the first portion and the second portion and one of the first portion and the second portion to atmosphere.

Inventors:
VESTGÅRD, Bård (Parkveien 10, 3413 Lier, 3413, NO)
LJØSNE, Knut Tore (Toppåsveien 71, 1262 Oslo, 1262, NO)
Application Number:
IB2016/054757
Publication Date:
February 08, 2018
Filing Date:
August 05, 2016
Export Citation:
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Assignee:
KONGSBERG AUTOMOTIVE AS (Dyrmyrgata 48, P.O. Box 62, 3601 Kongsberg, 3601, NO)
International Classes:
F15B11/12; F15B15/14; F15B15/20; F16H61/30
Domestic Patent References:
WO2008063104A12008-05-29
Foreign References:
US4308018A1981-12-29
FR2889566A12007-02-09
DE102006018733B32007-10-18
US20030136254A12003-07-24
US6196077B12001-03-06
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Claims:
WHAT IS CLAIMED IS:

1. A position actuator comprising:

a cylinder housing forming a fluid chamber having a first portion and a second portion; a movable main piston disposed in said cylinder housing between said first portion and said second portion;

a piston rod firmly attached to said main piston and extending through one end of said cylinder housing; and

a ventilation device disposed in said chamber and cooperating with said main piston to ventilate air between either one of said first portion and said second portion and one of said first portion and said second portion to atmosphere.

2. A position actuator as set forth in claim 1 wherein said ventilation device includes a ventilation passage extending through said main piston and communicating with said first portion and said second portion.

3. A position actuator as set forth in claim 2 wherein said ventilation passage includes a restriction having a diameter less than a diameter of a remainder of said ventilation passage.

4. A position actuator as set forth in claim 2 wherein said ventilation device includes a valve disposed in said ventilation passage.

5. A position actuator as set forth in claim 4 wherein said valve comprises a valve member extending axially and having a first enlarged end cooperating with one axial end of said ventilation passage and a second enlarged end cooperating with another axial end of said ventilation passage.

6. A position actuator as set forth in claim 5 wherein said valve member includes a flange extending radially outward from said first enlarged end to act as either one of a stop and to close said ventilation passage.

7. A position actuator as set forth in claim 4 wherein said valve comprises a ball and a spring to bias said ball.

8. A position actuator as set forth in claim 1 wherein said housing includes a first port communicating with said first chamber to receive pressurized air.

9. A position actuator as set forth in claim 8 wherein said housing includes a second port communicating with said second chamber and atmosphere.

10. A position actuator as set forth in claim 1 including a secondary piston disposed in said second chamber of said housing between said main piston and another end of said cylinder housing.

1 1. A position actuator as set forth in claim 10 including a coupling member coupling said secondary piston to said piston rod.

12. A position actuator as set forth in claim 10 wherein said housing includes a third port communicating with said second chamber to receive pressurized air.

13. A three-position actuator comprising:

a cylinder housing forming a fluid chamber having a first portion and a second portion; a movable main piston disposed in said cylinder housing to form said first portion on one side of said main piston and said second portion on an opposed side of said main piston;

a piston rod firmly attached to said main piston and extending through one end of said cylinder housing;

a push ring disposed in said first portion between said main piston and said one end of said cylinder housing; and

a ventilation device disposed in said chamber and cooperating with said main piston to ventilate air between either one of said first portion and said second portion and one of said first portion and said second portion to atmosphere.

14. A three-position actuator as set forth in claim 13 wherein said ventilation device includes a ventilation passage extending through said main piston and communicating with said first portion and said second portion.

15. A three-position actuator as set forth in claim 14 wherein said ventilation passage includes a restriction having a diameter less than a diameter of a remainder of said ventilation passage.

16. A three-position actuator as set forth in claim 14 wherein said ventilation device includes a valve disposed in said ventilation passage.

17. A three-position actuator as set forth in claim 16 wherein said valve comprises a valve member extending axially and having a first enlarged end cooperating with one axial end of said ventilation passage and a second enlarged end cooperating with another axial end of said ventilation passage.

18. A three-position actuator as set forth in claim 17 wherein said valve member includes a flange extending radially outward from said first enlarged end to act as either one of a stop and to close said ventilation passage.

19. A three-position actuator as set forth in claim 16 wherein said valve comprises a ball and a spring to bias said ball.

20. A three-position actuator comprising

a cylinder housing forming a fluid chamber having a first portion and a second portion; a movable main piston disposed in said cylinder housing to form said first portion on one side of said main piston and said second portion on an opposed side of said main piston; a piston rod firmly attached to said main piston and extending through one end of said cylinder housing;

a push ring disposed in said first portion between said main piston and said one end of said cylinder housing;

a secondary piston disposed in said second chamber of said housing between said main piston and another end of said cylinder housing;

a coupling member coupling said secondary piston to said piston rod; and

a ventilation device disposed in said chamber and cooperating with said main piston comprising a ventilation passage extending through said main piston and communicating with said first portion and said second portion to ventilate air between either one of said first portion and said second portion and one of said first portion and said second portion to atmosphere.

21. A transmission unit comprising:

at least one shift rail for actuating at least one gear;

at least one actuator cooperating with the at least one shift rail; and

said at least one actuator comprising a cylinder housing forming a fluid chamber having a first portion and a second portion, a movable main piston disposed in said cylinder housing between said first portion and said second portion, a piston rod firmly attached to said main piston and extending through one end of said cylinder housing, and a ventilation device disposed in said chamber and cooperating with said main piston to ventilate air between either one of said first portion and said second portion and one of said first portion and said second portion to atmosphere.

22. A transmission unit as set forth in claim 21 wherein said ventilation device includes a ventilation passage extending through said main piston and communicating with said first portion and said second portion.

23. A transmission unit as set forth in claim 22 wherein said ventilation passage includes a restriction having a diameter less than a diameter of a remainder of said ventilation passage.

24. A transmission unit as set forth in claim 22 wherein said ventilation device includes a valve disposed in said ventilation passage.

25. A transmission unit as set forth in claim 24 wherein said valve comprises a valve member extending axially and having a first enlarged end cooperating with one axial end of said ventilation passage and a second enlarged end cooperating with another axial end of said ventilation passage.

26. A transmission unit as set forth in claim 25 wherein said valve member includes a flange extending radially outward from said first enlarged end to act as either one of a stop and to close said ventilation passage.

27. A transmission unit as set forth in claim 24 wherein said valve comprises a ball and a spring to bias said ball.

28. A transmission unit as set forth in claim 21 wherein said housing includes channel communicating with said first chamber and atmosphere.

29. A transmission unit as set forth in claim 28 wherein said housing includes second channel communicating with said second chamber and atmosphere.

Description:
POSITION ACTUATOR HAVING PNEUMATIC VENTILATION

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention relates generally to position actuators for powertrains and, more specifically, to a position actuator having pneumatic ventilation for a powertrain of a vehicle.

2. Description of Related Art

[0002] It is known to provide a pneumatically actuated three-position actuator for actuating components in a powertrain such as gears and clutches in a transmission. An example of such a three-positon actuator is disclosed in U.S. Patent Application Publication No. 2003/0136254 to Hirano et al. In this patent publication, the three-positon actuator includes a housing, a movable internal piston disposed in a chamber within the housing, and a piston rod extending axially from the piston through one end of the housing. For such a three-position actuator, a partition wall divides a housing into two pressure chambers. Typically, air is used to regulate pressure during stroke of the internal piston to move the shift rail to synchronize engagement and disengagement of the gear. However, it can be difficult to control a speed of the internal piston to move the shift rail into synchronization or blocking positions, into an end stop position, and into a neutral position.

[0003] Attempts have been made to reduce shift shock by using air to automatically control shifting. An example of an automatic shift control device for an electronic pneumatic shift system is disclosed in U.S. Patent No. 6,196,077 to Lee. In this patent, a shift control device includes a first cylinder and a second cylinder. Air is supplied to and exhausted from the first cylinder and the second cylinder by operation of a magnetic valve assembly which operates according to signals output from the ECU. However, this valve assembly is disposed external to the shift control device and is relatively complex and costly, which is undesired.

[0004] Therefore, it is desirable to provide a position actuator having a mechanism for controlling a speed profile of a shift rail into synchronization or blocking positions, into an end stop position, and into a neutral position. Thus, there is a need in the art to provide a position actuator having pneumatic ventilation that meets this desire.

SUMMARY OF THE INVENTION

[0005] Accordingly, the present invention provides a position actuator having pneumatic ventilation for control of air piston velocity profile in gear shift actuators for a transmission of a vehicle.

[0006] In one embodiment, the present invention provides a position actuator including a cylinder housing forming a fluid chamber having a first portion and a second portion, a movable main piston disposed in the cylinder housing between the first portion and the second portion, and a piston rod firmly attached to the main piston and extending through one end of the cylinder housing. The position actuator also includes a ventilation device disposed in the chamber and cooperating with the main piston to ventilate air between either one of the first portion and the second portion and one of the first portion and the second portion to atmosphere.

[0007] One advantage of the present invention is that the position actuator has pneumatic ventilation for controlling a speed profile of a shift rail into synchronization or blocking positions, into an end stop position, and into a neutral position. Another advantage of the present invention is that the position actuator includes a ventilation device mounted inside a main piston of the position actuator. Yet another advantage of the present invention is that the position actuator includes a relatively low cost ventilation device. Still another advantage of the present invention is that the position actuator includes a ventilation device, typically a valve, which under certain conditions of position and/or pressure differential, the valve will ventilate air from one chamber to the other or to atmosphere.

[0008] Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a fragmentary elevational view of a position actuator having pneumatic ventilation, according to one embodiment of the present invention, illustrated in operational relationship with a portion of a powertrain.

[0010] FIG. 2 is an enlarged fragmentary elevational view of the position actuator having pneumatic ventilation of FIG. 1 illustrated in a first operational position.

[0011] FIG. 3 is a view similar to FIG. 2 illustrating the position actuator having pneumatic ventilation in a second operational position.

[0012] FIG. 4 is a view similar to FIG. 2 illustrating the position actuator having pneumatic ventilation in a third operational position.

[0013] FIG. 5 is a view similar to FIG. 2 illustrating the position actuator having pneumatic ventilation in a fourth operational position. [0014] FIG. 6 is a view similar to FIG. 2 illustrating the position actuator having pneumatic ventilation in a fifth operational position.

[0015] FIG. 7 is a view similar to FIG. 2 illustrating the position actuator having pneumatic ventilation illustrated in a sixth operational position.

[0016] FIG. 8 is a view similar to FIG. 2 illustrating the position actuator having pneumatic ventilation illustrated in a seventh operational position.

[0017] FIG. 9 is a view similar to FIG. 2 illustrating the position actuator having pneumatic ventilation illustrated in an eighth operational position.

[0018] FIG. 10 is a view similar to FIG. 2 illustrating ; the position actuator having pneumatic ventilation in a ninth operational position.

[0019] FIG. 11 is a view similar to FIG. 2 illustrating ; the position actuator having pneumatic ventilation illustrated in a tenth operational position.

[0020] FIG. 12 is a view similar to FIG. 2 illustrating ; the position actuator having pneumatic ventilation illustrated in an eleventh operational position.

[0021] FIG. 13 is a view similar to FIG. 2 illustrating ; the position actuator having pneumatic ventilation illustrated in a twelfth operational position.

[0022] FIG. 14 is an enlarged fragmentary elevational view of another embodiment, according to the present invention, of the position actuator having pneumatic ventilation of FIG. 2.

[0023] FIG. 15 is an enlarged fragmentary elevational view of yet another embodiment, according to the present invention, of the position actuator having pneumatic ventilation of FIG. 2. [0024] FIG. 16 is a graph of ventilation for the position actuator of FIGS. 1 through 15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS)

[0025] As disclosed in FIGS. 1 through 13, one embodiment of a position actuator 10, according to the present invention, having pneumatic ventilation is shown as a pneumatic shift or position actuator for moving components of a vehicle powertrain (not shown) such as gears and clutches in an automized transmission or an automatic manual transmission. In the embodiment illustrated in FIG. 1 , the position actuator 10 is used to move a shift rail 1 1 to engage and disengage at least one gear in the transmission. It should be appreciated that the positon actuator 10 may be used in other embodiments for the vehicle other than the powertrain. It should also be appreciated that the position actuator 10 may be a two-position actuator or a three-position actuator.

[0026] Referring to FIGS. 2-13, the positon actuator 10 includes a cylinder housing 12 extending axially. The cylinder housing 12 is generally cylindrical in shape with a generally circular cross-section. The cylinder housing 12 has a wall 14 forming a fluid chamber 16 therein. The chamber 16 has a first portion 18, a second portion 20, and a third portion 21. The first portion 18 has a diameter greater than a diameter of the second portion 20 and the second portion 20 has a diameter greater than a diameter of the third portion 21. The cylinder housing 12 also extends axially between a first end 22 and a second end 24 and has a first shoulder or step 26 disposed axially between the first portion 18 and the second portion 20 to form an axial stop for a push ring 52 to be described and a second shoulder or step 27 disposed axially between the second portion 20 and the third portion 21. The cylinder housing 12 includes an opening or aperture 28 extending axially through the first end 22 and fluidly communicating with the first portion 18 of the chamber 16. The aperture 28 allows a piston rod 38 to be described to extend through the first end 22 of the cylinder housing 12. It should be appreciated that the cylinder housing 12 may have any suitable shape. It should also be appreciated that the ends 22 and 24 may be end covers.

[0027] The positon actuator 10 also includes a movable internal main piston 30 disposed in the second portion 20 of the chamber 16. The main piston 30 is generally cylindrical in shape. The main piston 30 has a diameter less than a diameter of the second portion 20 of the cylinder housing 12 to allow the main piston 30 to be movable axially in the second portion 20 of the chamber 16 of the cylinder housing 12. The main piston 30 includes a central aperture 32 extending axially therethrough to receive a piston rod 38 to be described. The central aperture 32 may include a reduced diameter portion 33. The main piston 30 has a reduced diameter portion 34 at one end. The reduced diameter portion 34 has a diameter less than a diameter of the main piston 30. The main piston 30 also has one or more grooves 36 extending circumferentially and radially therein and spaced axially to receive one or more seals 80 to be described. In one embodiment, the main piston 30 is integral, unitary, and one-piece. It should be appreciated that the seals 80 engage the wall 14 of the cylinder housing 12 and prevent airflow past the main piston 30.

[0028] The position actuator 10 further includes a piston rod 38 connected to and extending axially from the main piston 30 for actuation of a component such as the shift fork 11. The piston rod 38 has a first portion 40 extending axially through the aperture 28 and into the central aperture 32 and a second portion 42 extending axially from the first portion 40 and into the reduced diameter portion 33 of the central aperture 32 of the main piston 30. The first portion 40 has a first diameter and the second portion 42 has a second diameter less than the first diameter. In one embodiment, the piston rod 38 is integral, unitary, and one-piece. It should be appreciated that a seal is disposed in the cylinder housing 12 about the piston rod 38 and prevent airflow past the piston rod 38. It should also be appreciated that one end of the first portion 40 is coupled to the shift rail 1 1 via an aperture 43 extending diametrically therethrough.

[0029] The position actuator 10 also includes at least one port or channel, generally indicated at 44, in the wall 14 of the cylinder housing 12. The at least one port 44 extends radially into the wall 14 of the cylinder housing 12. In one embodiment, the at least one port 44 includes a first port 46, a second port 48, a third port 50, and a fourth port 52. The first port 46 extends radially inward into the wall 14 of the cylinder housing 12 on one side of the main piston 30 to allow fluid such as air to communicate with the first portion 18 of the chamber 16 between the main piston 30 and the first end 22 of the cylinder housing 12. The second port 48 extends radially inward into the wall 14 of the cylinder housing 12 on another side of the main piston 30 to allow fluid to communicate with the second portion 20 and third portion 21 of the chamber 16 at the second step 27 of the cylinder housing 12. The third port 50 is disposed axially between the first channel 46 and the second channel 48 and extends radially inward into the wall 14 of the cylinder housing 12 to allow fluid to communicate with the first portion 18 and the second portion 20 of the chamber 16 at the first step 26 of the cylinder housing 12. The fourth port 51 extends radially inward into the wall 14 of the cylinder housing 12 on one side of a secondary piston 60 to be described to allow fluid such as air to communicate with the third portion 21 of the chamber 16 between the secondary piston 30 and the second end 24 of the cylinder housing 12. It should be appreciated that the port 44 may have any suitable shape. It should also be appreciated that the first and second ports 46 and 48 are working ports and the third and fourth ports 50 and 51 are venting ports. It should further be appreciated that valves (not shown) for raising and lowering the pressure of the fluid may be provided for the chamber 16.

[0030] The position actuator 10 further includes a push ring 52 disposed axially in the first portion 18 of the chamber 16 between the main piston 30 and the first end 22 of the cylinder housing 12. The push ring 52 includes a central aperture 54 extending axially therethrough to receive the reduced diameter portion 34 of the main piston 30. The push ring 52 has a reduced diameter portion 56 at one end. The reduced diameter portion 56 has a diameter less than a diameter of the push ring 52. The push ring 52 has at least one groove 58 extending circumferentially and radially therein to receive at least one seal 80 to be described. In one embodiment, the push ring 52 is integral, unitary, and one-piece. It should be appreciated that the seal 80 engages the wall 14 of the cylinder housing 12 and prevents airflow past the push ring 52. It should also be appreciated that the push ring 52 forms a floating piston and is movable axially relative to the main piston 30.

[0031] The position actuator 10 further includes a secondary or balancing piston

60 disposed axially in the third portion 21 of the chamber 16 between the main piston 30 and the second end 24 of the cylinder housing 12. The secondary piston 60 includes a central cavity 62 extending axially therein to receive a connector 70 to be described. The secondary piston 60 has a reduced diameter portion 64 at one end. The reduced diameter portion 64 has a diameter less than a diameter of the secondary piston 60. The reduced diameter portion 64 has a flange 66 at one axial end extending radially inward to engage the connector 70. The secondary piston 60 has at least one groove 68 extending circumferentially and radially therein to receive at least one seal 80 to be described. In one embodiment, the connector 70 is integral, unitary, and one-piece. It should be appreciated that the seal 80 engages the wall 14 of the cylinder housing 12 and prevents airflow past the secondary piston 60.

[0032] The position actuator 10 includes a connector 70 disposed axially between the main piston 30 and the secondary piston 60. The connector 70 is generally cylindrical in shape and extends axially. The connector 70 has an aperture 72 extending axially therethrough with a cavity 74 at one end thereof to receive a fastener (not shown) to fasten the connector to the second portion 42 of the piston rod 38. The connector 70 includes a first flange 76 extending radially outwardly at one axial end to engage the main piston 30 and a second flange 78 extending radially outwardly at the other axial end and disposed in the central cavity 62 of the secondary piston 60 to cooperate with the flange 66 of the reduced diameter portion 64 of the secondary piston 60. It should be appreciated that the secondary piston 60 is free to move within the stroke boundaries defined by the connector 70.

[0033] The position actuator 10 also includes a seal 80 disposed in the groove 36 of the main piston 30, the groove 58 of the push ring 52, and the groove 68 of the secondary piston 60. The grooves 36, 58, and 68 are generally annular and rectangular in shape, but may have any suitable shape. The grooves 36 extend radially inwardly into a wall of the main piston 30 and the reduced diameter portion 34, the groove 58 extends radially inwardly into a wall of the push ring 52, and the groove 68 extends radially inwardly into a wall of the secondary piston 60. The seal 80 is generally annular in shape. In one embodiment, the seal 80 has a generally rectangular in shape. The seal 80 is made of a flexible elastomeric material such as rubber. The seal 80 is integral, unitary, and one-piece. It should be appreciated that the seal 80 may be any suitable type of seal such as a lip seal, o-ring, etc. [0034] The position actuator 10 further includes a ventilation device, generally indicated at 82, disposed in the chamber 16 and cooperating with the main piston 30 to ventilate air either in or from the chamber 16 such as between either the first portion 18 and the second portion 20, the first portion 18 to atmosphere, or the second portion 20 to atmosphere. In one embodiment, the ventilation device 82 includes a ventilation passage 84 extending through the main piston 30 and communicating with the first portion 18 and the second portion 20 to ventilate air either between the first portion 18 and the second portion 20, from the first portion 18 to atmosphere, or from the second portion 20 to atmosphere. The ventilation passage 84 has a cavity 86 at one axial end to communicate with the first portion 18 and a cavity at the other axial end to communicate with the second portion 20. The ventilation device 82 may include a valve 88 disposed in the ventilation passage 84. The valve 88 is a valve member that extends axially and has a first enlarged end 90 cooperating with the cavity 86 of the ventilation passage 84 and a second enlarged end 92 cooperating with the axial end of the cavity 87 of the ventilation passage 84. The valve 88 may include a flange 94 extending radially outward from the first enlarged end 90 to act either as a stop or to close the ventilation passage 84. In one embodiment, the valve 88 is integral, unitary, and one-piece. It should be appreciated that the valve 88 may meet other objects such as the first end 22 of the cylinder 14 and the secondary piston 60 to decide opening and closing positions of the valve 88. It should also be appreciated that the ventilation device 82 may ventilate air from the first portion 18 through the first channel 46 and from the second portion 20 through the second channel 48. It should further be appreciated that the ventilation device 82 may ventilate air from the first portion 18 and from the second portion 20 to atmosphere. [0035] As illustrated in FIG. 2-13, the positon actuator 10 has a first area Al , a second area A2, a third area A3, and a fourth area A4 of the chamber 16 of the cylinder housing 12. The first area Al is defined by the diameter of the central aperture 54 of the push ring 52 minus the diameter of the first portion 40 of the piston rod 38, the second area A2 is defined by the diameter of the second portion 20 minus the diameter of the third portion 21 , the third area A3 is defined by the diameter of the push ring 52 minus the diameter of the central aperture 54 of the push ring 52, and the fourth area A4 is defined by a diameter of the third portion 21 of the chamber 16.

[0036] In operation of the position actuator 10, as illustrated in FIG. 2, the main piston 30 has a first, middle or neutral operational position. Initially, the valve 88 of the ventilation device 82 may be either open or closed. When airflow enters through the first channel 46 into the first portion 18 of the chamber 16 and airflow enters through the second channel 48 into the second portion 20 of the chamber 16 and pressurizes the first portion 18 and the second portion 20, the valve 88 may either close or stay open. It should be appreciated that neither position of the valve 88 affects the function as the forces on the main piston 30 are decided by the third area A3 and the fourth area A4, which will receive the same pneumatic pressure. It should also be appreciated that, at simultaneous pressurization of the first portion 18 and second portion 20, the valve 88 closes.

[0037] Referring to FIG. 3, the main piston 30 has a second or engaged operational position. When airflow enters through the first channel 46 into the first portion 18 of the chamber 16 and pressurizes the first portion 18, the valve 88 of the ventilation device 82 closes and the main piston 30 moves toward the second end 24 to a synchronization position. [0038] Referring to FIG. 4, the main piston 30 has a third or synchronization operational position. When the main piston 30 moves into the synchronization position, the valve 88 of the ventilation device 82 meets the end and stops.

[0039] Referring to FIG. 5, the main piston 30 has a fourth operational position.

During synchronization, the valve 88 of the ventilation device 82 stays in the closed position.

[0040] Referring to FIG. 6, the main piston 30 has a fifth operational position.

After synchronization, the valve 88 of the ventilation device 82 opens.

[0041] Referring to FIG. 7, the main piston 30 has a sixth operational position.

During end of stroke, the valve 88 of the ventilation device 82 is open and connects the first portion 18 and second portion 20 of the chamber 16 to avoid excessive acceleration into an end stop position.

[0042] Referring to FIG. 8, the main piston 30 has a seventh operational position.

At a small distance from the end stop position, the valve 88 of the ventilation device 82 closes, and cushioning by the second portion 20 of the chamber 16 occurs, and a hard end stop of the main piston 30 is avoided.

[0043] Referring to FIG. 9, the main piston 30 has an eighth or engaged operational position. In the engaged position, the main piston 30 is ready for two sided pressurization in the chamber 16 for the main piston 30 to enter the neutral position.

[0044] Referring to FIG. 10, the main piston 30 has a ninth operational position.

When airflow enters through the second channel 48 into the second portion 20 of the chamber 16 and pressurizes the second portion 20, the valve 88 closes and the main piston 30 moves toward the first end 22 to cause the shift rail 11 to synchronize to engage the gear. It should be appreciated that with the valve 88 closed, full forces are available on the entire driving side of the main piston 30. It should also be appreciated that, in this position, dogs (not shown) of the transmission are disengaged and pressure on both sides of the main piston 30 is close to being equal.

[0045] In neutral, the main piston 30 is pressurized from both sides, and the valve

88 of the ventilation device 82 may open, thus not affecting the function as the forces on the main piston 30 are decided by A3 and A4, which shall see the same pneumatic pressure anyway. It should be appreciated that, as the main piston 30 moves toward the first end 22 and engages, the valve 88 of the ventilation device 82 closes.

[0046] Referring to FIG. 11, the main piston 30 has a tenth operational position.

After synchronization of the shift rail 11 to shift the gear, the main piston 30 continues to move toward the first end 22 of the cylinder housing 12 to a third position to cause the shift rail 11 to engage the gear and the valve 88 opens.

[0047] Referring to FIG. 12, the main piston 30 has an eleventh operational position. In this position, the main piston 30 continues to move toward the first end 22 to a fourth or cushion position. The flange 94 acts as an end stop upon engaging the first end 22 and the valve 88 starts to close to allow for cushion of the main piston 30.

[0048] Referring to FIG. 13, the main piston 30 has a twelfth or engaged operational position. When the gear is engaged, the valve 88 is closed. The main piston 30 is ready to disengage the gear by two sided simultaneous pressurization when airflow enters through the first channel 46 into the first portion 18 of the chamber 16 and airflow enters through the third channel 50 into the first portion 18 of the chamber 16 and pressurizes the first portion 18 of the chamber 16. [0049] Referring to FIG. 14, another embodiment, according to the present invention, of the position actuator 10 is shown. Like parts of the position actuator 10 have like reference numerals and like parts of the ventilation device 82 of FIGS. 2-13 have like reference numerals increased by one hundred (100). In this embodiment, the position actuator 10 includes a ventilation device, generally indicated at 182, disposed in the chamber 16 and cooperating with the main piston 30 to ventilate air either in or from the chamber 16 such as between either the first portion 18 and the second portion 20, the first portion 18 to atmosphere, or the second portion 20 to atmosphere. In one embodiment, the ventilation device 182 includes a ventilation passage 184 extending through the main piston 30 and communicating with the first portion 18 and the second portion 20 to ventilate air either between the first portion 18 and the second portion 20, from the first portion 18 to atmosphere, or from the second portion 20 to atmosphere. The ventilation passage 184 has a restriction 185 formed as a reduced diameter between the axial ends that acts as the valve 188 disposed in the ventilation passage 184. It should be appreciated that the operation of the position actuator 10 is similar to that of FIGS. 1-13.

[0050] Referring to FIG. 15, yet another embodiment, according to the present invention, of the position actuator 10 is shown. Like parts of the position actuator 10 have like reference numerals and like parts of the ventilation device 82 of FIGS. 2-13 have like reference numerals increased by two hundred (200). In this embodiment, the position actuator 10 further includes a ventilation device, generally indicated at 282, disposed in the chamber 16 and cooperating with the main piston 30 to ventilate air either in or from the chamber 16 such as between either the first portion 18 and the second portion 20, the first portion 18 to atmosphere, or the second portion 20 to atmosphere. In one embodiment, the ventilation device 282 includes a ventilation passage 284 extending through the main piston 30 and communicating with the first portion 18 and the second portion 20 to ventilate air either between the first portion 18 and the second portion 20, from the first portion 18 to atmosphere, or from the second portion 20 to atmosphere. The ventilation passage 284 has a cavity 287 at one axial end to communicate with the second portion 20. The ventilation device 282 includes a valve 288 formed by a ball 294 and a spring 296 disposed in the cavity 287 to open and close the ventilation passage 284. In one embodiment, the ball 294 is generally spherically shaped and the spring 296 is of a coil type that extends axially. The spring 296 has one end contacting the ball 294 to bias the ball 294 to close the ventilation passage 284 and another end cooperating with the end of the cavity 287 such that the spring 296 remains disposed in the cavity 287. It should be appreciated that, when the air pressure in the first portion 18 is greater than the air pressure in the second portion 20, the air in the ventilation passage 284 will move the ball 294 against the spring 296 and open the ventilation passage 284. It should also be appreciated that, when the air pressure in the first portion 18 is less than the air pressure in the second portion 20, the spring 294 will move the ball 294 against the end of the cavity 287 and close the ventilation passage 284.

[0051] Referring to FIG. 16, a graph, generally shown at 300, shows typical movement of the rail 11 (gear) from a neutral position via synchronization to a gear engaged position. The graph 300 includes a vertical axis 302 in distance such as millimeters and a horizontal axis 304 in time such as seconds. The graph 300 also includes a solid line 306 that illustrates a normal approach to gear synchronization and gear engagement, with a steep slope (risk of hard stops) going into gear synchronization and gear engagement. The graph 300 further includes a dotted line 308 that illustrates position dependent ventilation between the first portion 18 and the second portion 20 of the position actuator 10, damped and with a smaller slope. It should be appreciated that the slope is the derivative of position such as speed. It should also be appreciated that the target is to increase speed in the non-risky region while reducing speed in the risky gear and synchronization regions.

[0052] Accordingly, the present invention provides a ventilation device 82, 182,

282 inside a main piston 30 of the shift or position actuator 10, which based on piston position and/or chamber pressure ventilates an amount of air (with resulting change in chamber pressures and velocity) either into an opposite chamber or atmosphere. It should be appreciated that the target of the present invention is to tune the velocity profile of the main piston 30 to a more desirable one in terms of particularly synchronizing and engaging a gear, reaching an in-gear and stop positions, and reaching a middle neutral position for the position actuator 10.

[0053] The present invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation.

[0054] Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, the present invention may be practiced other than as specifically described.




 
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