WO2017176261A1

WO2017176261A1 - Solenoid for solenoid-actuated valve in automatic transmission

Info

Publication number: WO2017176261A1
Application number: PCT/US2016/026200
Authority: WO
Inventors: Kevin A. SCHNEIDER; Garrett R. Holmes
Original assignee: Borgwarner Inc.
Priority date: 2016-04-06
Filing date: 2016-04-06
Publication date: 2017-10-12

Abstract

A solenoid (56) for a solenoid-actuated valve (26) for use in an automatic transmission (14) includes a flux tube (68), a pole piece disposed axially from the flux tube (68) to form a magnetic air gap (80) therebetween, and an alignment component (58) overmolded to the flux tube (68) and pole piece (74) to provide a non-magnetic air gap (92) between the flux tube (68) and the pole piece (74).

Description

SOLENOID FOR SOLENOID-ACTUATED VALVE IN AUTOMATIC

TRANSMISSION

BACKGROUND OF INVENTION

1. Field of Invention

[0001] The present invention relates generally to solenoid-actuated valves and, more specifically, to a solenoid for a solenoid-actuated valve in an automatic transmission.

2. Description of the Related Art

[0002] Conventional vehicles known in the art typically include an engine having a rotational output that provides a rotational input into a transmission such as an automatic transmission for a powertrain system of the vehicle. The transmission changes the rotational speed and torque generated by an output of the engine through a series of predetermined gearsets to transmit power to one or more wheels of the vehicle, whereby changing between the gearsets enables the vehicle to travel at different vehicle speeds for a given engine speed.

[0003] In addition to changing between the gearsets, the automatic transmission is also used to modulate engagement with the engine, whereby the transmission can selectively control engagement with the engine so as to facilitate vehicle operation. By way of example, torque translation between the engine and the automatic transmission is typically interrupted while the vehicle is parked or idling, or when the transmission changes between the gearsets. In conventional automatic transmissions, modulation is achieved via a hydrodynamic device such as a hydraulic torque converter. However, modern automatic transmissions may replace the torque converter with one or more electronically and/or hydraulically actuated clutches (sometimes referred to in the art as a "dual clutch" automatic transmission). Automatic transmissions are typically controlled using hydraulic fluid, and include a pump assembly, one or more hydraulic solenoid-actuated valves, and an electronic controller. The pump assembly provides a source of fluid power to the solenoid-actuated valves which, in turn, are actuated by the controller so as to selectively direct hydraulic fluid throughout the automatic transmission to control modulation of rotational torque generated by the output of the engine. The solenoid- actuated valves are also typically used to control hydraulic fluid for torque translation to change between the gearsets of the automatic transmission, and may also be used to control hydraulic fluid used to cool and/or lubricate various components of the transmission in operation.

[0004] It is known to provide a solenoid for a solenoid-actuated valve having a three- piece pole tube. To avoid a magnetic short-circuit, a non-magnetic ring between two magnetic pole pieces is welded. To achieve a high force level of an electromagnetic actuator, it is essential that a radial air gap between the pole tube and a magnet armature is as low as possible. Further, small eccentricities can result in an unbalanced magnetic field and it is important to arrange the components concentric to each other. Thus, there is a need in the art to provide a solenoid for a solenoid-actuated valve that increases magnetic efficiency for use in an automatic transmission.

SUMMARY OF THE INVENTION

[0005] The present invention provides a solenoid for a solenoid-actuated valve for use in an automatic transmission including a flux tube, a pole piece disposed axially from the flux tube to form a magnetic air gap therebetween, and an alignment component overmolded to the flux tube and pole piece to provide a non-magnetic air gap and alignment between the flux tube and the pole piece. [0006] One advantage of the present invention is that a new solenoid for a solenoid- actuated valve is provided for use in an automatic transmission. Another advantage of the present invention is that the solenoid includes a flux tube, alignment tube (overmolded component), and pole piece. Yet another advantage of the present invention is that the solenoid includes an overmolded component and the overmolding process provides precision alignment between the flux tube and pole piece and also eliminates the need for a precision component to give alignment. Still another advantage of the present invention is that the solenoid, by implementing this overmold technology, increases magnetic efficiency by creating a permanent gap between the upper and lower tube called a bridge area, which is filled with polymer based material that has very low magnetic permeability (similar to air) and this means less force is wasted, therefore more can be used for work within the solenoid. A further advantage of the present invention is that the solenoid increases magnetic system efficiency because no flux is wasted in the bridge area due to saturation. Yet a further advantage of the present invention is that the solenoid eliminates the need to have an additional precision component due to a three- piece design. Still a further advantage of the present invention is that the solenoid eliminates the possibility of magnetic mud getting trapped between the bobbin and the flux tube. Another advantage of the present invention is that the solenoid eliminates at least one assembly step. Yet another advantage of the present invention is that the solenoid increases the force output and reduces a can thickness, making the can cheaper and more form friendly. Still another advantage of the present invention is that the solenoid provides less critical outside features of the flux tube and pole piece, therefore other manufacturing processes can be used to reduce the net cost of the parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Other objects, features, and advantages of the present invention will be readily appreciated as the same becomes better understood after reading the subsequent description taken in connection with the accompanying drawings wherein:

[0008] Figure 1 is a schematic view of a vehicle with a powertrain system including a solenoid-actuated valve, according to the present invention;

[0009] Figure 2 is a cross-sectional view of one embodiment of the solenoid-actuated valve of Figure 1 with a valve member in a first operational position;

[0010] Figure 3 is a view similar to Figure 2 illustrating the solenoid-actuated valve with the valve member in a second operational position;

DETAILED DESCRIPTION OF THE INVENTION

[0011] Referring now to the figures, where like numerals are used to designate like structure unless otherwise indicated, a vehicle is schematically illustrated at 10 in Figure 1. The vehicle 10 includes an engine 12 in rotational communication with an automatic transmission 14 of a powertrain system. The engine 12 generates rotational torque which is selectively translated to the automatic transmission 14 which, in turn, translates rotational torque to one or more wheels, generally indicated at 16. To that end, a pair of continuously-variable joints 18 translates rotational torque from the automatic transmission 14 to the wheels 16. It should be appreciated that the automatic transmission 14 of Figure 1 may be of a type employed in a conventional "transverse front wheel drive" powertrain system for the vehicle 10. It should also be appreciated that the engine 12 and/or automatic transmission 14 could be of any suitable type, configured in any suitable way sufficient to generate and translate rotational torque so as to drive the vehicle 10, without departing from the scope of the present invention.

[0012] The automatic transmission 14 multiplies the rotational speed and torque generated by an output of the engine 12 through a pulley assembly 22. In one embodiment, a forward-reverse gearset 20 is disposed between the engine 12 and the pulley assembly 22. The pulley assembly 22 includes an input or primary pulley (not shown) having a fixed sheave (not shown) and a displaceable or movable sheave (not shown), with a primary sheave servo chamber (not shown) positioned to admit and discharge fluid and thus adjust the position of movable sheave. The pulley assembly 22 also includes a secondary or output pulley (not shown) having an axially fixed sheave (not shown) and an axially displaceable or movable sheave (not shown), with a secondary sheave servo chamber (not shown) positioned to admit and discharge fluid to change the effective diameter of the pulley. The pulley assembly 22 further includes a belt or chain (not shown) intercoupling the pulleys. The output of secondary pulley is passed to a differential assembly (not shown), which passes output drive to the joints 18, in turn, to the wheels 16 of the vehicle. It should be appreciated that this drive train, from the engine 12 to the joints 18 is completed when fluid under pressure is admitted into the starting clutch servo chamber.

[0013] In addition, the automatic transmission 14 is also used to modulate engagement with the engine 12, whereby the transmission 14 can selectively control engagement with the engine 12 so as to facilitate vehicle operation. By way of example, torque translation between the engine 12 and the automatic transmission 14 is typically interrupted while the vehicle 10 is parked or idling, or when the transmission 14 changes between gears of the gearset 20. In the automatic transmission 14, modulation of rational torque between the engine 12 and transmission 14 is achieved via a hydrodynamic device such as a hydraulic torque converter (not shown, but generally known in the art). An example of an automatic transmission 14 is disclosed in U.S. Patent No. 4,712,453 to Haley, the disclosure of which is hereby incorporated by reference in its entirety. It should be appreciated that the automatic transmission 14 is adapted for use with vehicles such as automotive vehicles, but could be used in connection with any suitable type of vehicle.

[0014] Irrespective of the specific configuration of the powertrain system, the automatic transmission 14 is typically controlled using hydraulic fluid. Specifically, the automatic transmission 14 is cooled, lubricated, and actuated, and modulates torque using hydraulic fluid. To these ends, the automatic transmission 14 typically includes an electronic controller 24 in electrical communication with one or more hydraulic solenoid-actuated valves 26 (see Figure 1) used to direct, control, or otherwise regulate flow of fluid throughout the transmission 14, as described in greater detail below. In order to facilitate the flow of hydraulic fluid throughout the automatic transmission 14, the vehicle 10 includes at least one or more pumps, generally indicated at 28, to supply pressurized fluid to the transmission 14. It should be appreciated that the pump 28 provides pressurized hydraulic fluid to the solenoid-actuated valves 26.

[0015] Referring now to Figure 2, one embodiment of a solenoid-actuated valve 26, according to the present invention, is shown in connection with the automatic transmission 14. The solenoid-actuated valve 26 includes a valve body 30 having a valve bore 32. The valve bore 32 has a biasing end 34 and an actuating end 36. The valve body 30 also includes multiple ports with at least one inlet 38 and at least one outlet 40 adapted to provide fluid communication with a source of pressurized hydraulic fluid and a return to the source of pressure such as the pump 28. [0016] The solenoid-actuated valve 26 also includes a valve member 42 or a spool valve (i.e., hydraulic control valve) slideably disposed within the valve bore 32 of the valve body 30. The valve member 42 has a plurality of valve elements 44. The valve elements 44 are adapted to control the flow of pressurized hydraulic fluid between the ports of the valve body 30. The valve member 42 further includes a biasing end 50 and an actuating end 52. It should be appreciated that the valve member 42 is integral, unitary, and one-piece.

[0017] The solenoid-actuated valve 26 further includes a biasing return spring 54 disposed in the valve bore 32 between the biasing end 50 of the valve member 42 and the biasing end 34 of the valve bore 32. The solenoid valve 26 includes an end member 55 disposed in the biasing end 34 of the valve bore 32. It should be appreciated that the end member 55 is fixed to the valve body 30 and the valve member 42 moves axially relative to the valve body30.

[0018] The solenoid-actuated valve 26 also includes an electronically controlled solenoid, generally indicated at 56 and according to the present invention, for actuating the valve member 42 to control hydraulic fluid pressure between the inlet port 38 and the outlet port 40. The solenoid 56 includes an overmolded component such as a bobbin 58. The solenoid 56 also includes a can or housing 60 enclosing the bobbin 58. The bobbin 58 has a primary electromagnetic coil 62 wound thereon to create a magnetic field when energized. The solenoid 56 also includes a terminal 64 for connecting with the electromagnetic coil 62 and to ground (not shown). The coil 62 is made of copper wire. It should be appreciated that the terminal 64 receives a continuous variable, digital control signal from a primary driver (not shown) such as the electronic controller 24.

[0019] Accordingly, the electromagnetic coil 62 is independently controlled by respective continuous variable, digital control signals. The electronic controller 24 is connected to a pair of contacts (not shown) of the terminal 64 that is attached to the housing 60 of the solenoid 56. When engine conditions require clutching of the automatic transmission 14, the electronic controller 24 inputs a control signal to the solenoid 56 via the contacts and the terminal 64. The electronic controller 24 automatically controls actuation during automatic shifts. It should be appreciated that the electronic controller 24 could also be used for the vehicle 10 stopped on hills or the like. It should also be appreciated that the electronic controller 24 can function to sense the occurrence of a manual shift and send a signal to the solenoid 56 for actuating the solenoid-actuated valve 26.

[0020] The solenoid 56 further includes an internal diameter or channel 66 extending through a longitudinal axis of the bobbin 58. The actuating end 36 of the valve body 30 is disposed in the channel 66. The solenoid 56 also includes a flux tube 68 co-axially disposed within the channel 66. The flux tube 68 is generally cylindrical in shape with a generally circular cross-section. The flux tube 68 has a flange 70 extending radially outward from the end thereof. The flux tube 68 has an aperture 72 extending axially therethrough. The solenoid 56 also includes a pole piece 74. The pole piece 74 is generally cylindrical in shape with a generally circular cross-section. The pole piece 74 has an aperture 78 extending axially therethrough. The flux tube 68 and pole piece 74 are separated axially by a magnetic air gap 80. The pole piece 74 has a flange 82 extending radially outward from the end thereof. The flux tube 68 has a cavity 84 extending axially therein. The flux tube 68 extends axially and includes one or more undercuts 86 extending radially therein and circumferentially thereabout. The solenoid 56 includes an armature 88 disposed in the aperture 72 of the flux tube 68 and an actuator rod 90 is coupled to the armature 88 and extends through the aperture 78 in the pole piece 74. It should also be appreciated that the pole piece 74 may include undercuts 86 extending radially therein and circumferentially thereabout. It should also be appreciated that the bobbin 58 extends into the undercuts 86. It should further be appreciated that the armature 88 slides within the aperture 72 of the flux tube 68 and the actuator rod 90 slides co-axially with the pole piece 68.

[0021] To assemble the solenoid 56, the flux tube 68 and pole piece 74 are aligned with a core pin (not shown) and placed in a mold (not shown). Polymer based material such as plastic is injected in the mold to form the bobbin 58 insert overmolded to the flux tube 68 and pole piece 74 as one-piece, which precisely aligns inside diameters of the flux tube 68 and pole piece 74 where the armature 88 moves. The overmolded bobbin 58 fills the magnetic air gap 80 and provides a non-magnetic air gap 92 between the flux tube 68 and the pole piece 74. The undercuts 86 in the flux tube 68 help to mechanically lock the assembly together. It should be appreciated that the bobbin 58 may be formed by metal injection molding. It should also be appreciated that the coil 62 is wound about the bobbin 58 after overmolding. It should further be appreciated that the bobbin 58 is integral, unitary, and one-piece.

[0022] As illustrated in FIG. 2, when the electromagnetic coil 62 is un-energized, there is no magnetic field and the armature 88, actuator rod 90, and valve member 42 are disposed in a first operational state. As illustrated in FIG. 3, when the electromagnetic coil 62 is energized, the magnetic field moves the armature 68, actuator rod 90, and valve member 42, which are disposed in a second operational state.

[0023] 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. [0024] Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.

Claims

What is claimed is:

1. A solenoid (56) for a solenoid-actuated valve (26) for use in an automatic transmission (14), said solenoid comprising:

a flux tube (68);

a pole piece (74) disposed axially from said flux tube (68) to form a magnetic air gap (80) therebetween;

a movable armature (88) disposed in said flux tube (68) and said pole piece (74);

an alignment component (58) overmolded to said flux tube (68) and said pole piece (74) to provide a non-magnetic air gap (92) and alignment between said flux tube (68) and said pole piece (74).

2. A solenoid (56) as set forth in claim 1 including at least one undercut (86) in said flux tube (68) to mechanically lock said alignment component (58) and said flux tube (68) together.

3. A solenoid (56) as set forth in claim 1 wherein said alignment component (58) is made of a polymer based material.

4. A solenoid (56) as set forth in claim 1 wherein said alignment component (58) is formed by metal injection molding.

5. A solenoid (56) as set forth in claim 3 wherein said polymer based material is a dimensionally stable plastic.

6. A solenoid (56) as set forth in claim 1 including a coil (62) disposed about said bobbin (58).

7. A solenoid (56) as set forth in claim 6 including at least one terminal (64) connected to said coil (62).

8. A solenoid (56) as set forth in claim 6 wherein said coil (62) is made of copper wire.

9. A solenoid (56) as set forth in claim 1 including an actuator rod (90) coupled to said armature (88) and extending through said pole piece (74).

10. A solenoid (56) as set forth in claim 1 including a housing (60) disposed about said bobbin (58).

11. A solenoid (56) as set forth in claim 1 wherein said pole piece (74) has an inside diameter (78) therein.

12. A solenoid (56) as set forth in claim 11 wherein said flux tube (68) has an inside diameter (72) aligned with said inside diameter (78) of said pole piece (74).

13. A solenoid-actuated valve (26) comprising:

a solenoid (56);

a valve body (30) connected to and operatively associated with said solenoid (56), said valve body (30) having a valve bore (32) extending axially and at least one fluid inlet port (38) for fluid communication with said valve bore (32) and with a source of pressurized hydraulic fluid and at least one fluid outlet port (40) for fluid communication with said valve bore (32); a valve member (42) axially and slidingly disposed within said valve bore (32); and said solenoid (56) comprising a flux tube (68), a pole piece (74) disposed axially from said flux tube (68) to form a magnetic air gap (80) therebetween, and an alignment component (58) overmolded to said flux tube (68) and said pole piece (74) to provide a non-magnetic air gap (92) and alignment between said flux tube (68) and said pole piece (74).

14. A solenoid-actuated valve (26) as set forth in claim 13 including a least one undercut (86) in said flux tube (68) to mechanically lock said alignment component (58) and said flux tube (68) together.

15. A solenoid-actuated valve (26) as set forth in claim 13 wherein said flux tube (68) has an inside diameter (72) and said pole piece (74) has an inside diameter (78) aligned with said inside diameter (72) of said flux tube (68).