Direct-acting, non-close clearance solenoid-actuated valves

Abstract: Solenoid-actuated valves in a four-speed automatic transmission which are direct-acting and have a non-close clearance design to prevent dirt or other contaminants from interfering with the operation of said valves. The solenoid-actuated valves also include armature having an offset portion extending toward electromagnetic means to be offset toward the center inside the electromagnetic means for efficient magnetic flow.

Description: The present invention relates to a valve assembly for controlling fluid flow between a fluid supply source and a fluid actuating device in a vehicle transmission according to the preamble of claim 1. A valve assembly of this type is known from US-A-4 338 966. DE-U-1 673 074 discloses an electromagnetically actuated pneumatic pressure valve, wherein the armature actuating the valve member through a linkage has a projecting portion entering a cavity which is defined by the front end of the magnetic core and the coil wound thereon. A conventional vehicle transmission includes a hydrodynamic torque converter to transfer engine torques from engine crank shaft to a rotatable input member of the transmission through fluid-flow forces. The transmission also includes frictional units which couple the rotating input member to one or more members of a planetary gearset. Other frictional units, typically referred to as brakes, hold members of the planetary gearset stationary during flow of power. These frictional units are usually brake clutch assemblies or band brakes. The drive clutch assemblies can couple the rotating input member of the transmission to the desired elements of the planetary gearsets, while the brakes hold elements of these gearsets stationary. Such transmission systems also typically provide for one or more planetary gearsets in order to provide various ratios of torque and to ensure that the available torque and the respective tractive power demand are matched to each other. Transmissions are generally referred to as manually actuated or automatic transmissions. Manual transmissions generally include mechanical mechanisms for coupling rotating gears to produce different ratio outputs to the drive wheels. Automatic transmissions are designed to take automatic control of the frictional units, gear ratio selection and gear shifting. A thorough description of general automatic transmission design principals may be found in "Fundamentals of Automatic Transmissions and Transaxles," Chrysler Corporation Training Manual No. TM-508A. Additional descriptions of automatic transmissions may be found in U.S. Patent No. 3,631,744, entitled "Hydromatic Transmission," issued January 4, 1972 to Blomquist, et al., and U.S. Patent No. 4,289,048, entitled "Lock-up System for Torque Converter," issued on September 15, 1981 to Mikel, et al. Each of these patents is hereby incorporated by reference. In general, the major components featured in such an automatic transmission are: a torque converter as above-mentioned; fluid pressure-operated multi-plate drive or brake clutches and/or brake bands which are connected to the individual elements of the planetary gearsets in order to perform gear shifts without interrupting the tractive power; one-way clutches in conjunction with the frictional units for optimization of power shifts; and transmission controls such as valves for applying and releasing elements to shift the gears (instant of shifting), for enabling power shifting, and for choosing the proper gear (shift point control), dependent on shift-program selection by the driver (selector lever), accelerator position, the engine condition and vehicle speed. The control system of the automatic transmission is typically hydraulically operated through the use of several valves to direct and regulate the supply of pressure. This hydraulic pressure control will cause either the actuation or deactuation of the respective frictional units for effecting gear changes in the transmission. The valves used in the hydraulic control circuit typically comprise spring-biased spool valves, spring-biased accumulators and ball check valves. Since many of these valves rely upon springs to provide a predetermined amount of force, it will be appreciated that each transmission design represents a finely tuned arrangement of interdependent valve components. While this type of transmission control system has worked well over the years, it does have its limitations. For example, such hydraulically controlled transmissions are generally limited to one or a very small number of engines and vehicle designs. Therefore, considerable cost is incurred by an automobile manufacturer to design, test, build, inventory and repair several different transmission units in order to provide an acceptable broad model line for consumers. Additionally, it should be appreciated that such hydraulically controlled transmission systems cannot readily adjust themselves in the field to compensate for varying conditions such as normal wear on the components, temperature swings and changes in engine performance over time. While each transmission is designed to operate most efficiently within certain specific tolerances, typical hydraulic control systems are incapable of taking self corrective action on their own to maintain operation of the transmission at peak efficiency. However, in recent years, a more advanced form of transmission control system has been proposed, which would offer the possibility of enabling the transmission to adapt itself to changing conditions. In this regard, U.S. Patent No. 3,956,947, issued on May 18, 1976 to Leising, et al., which is hereby incorporated by reference, sets forth a fundamental development in this field. Specifically, this patent discloses an automatic transmission design which features an "adaptive" control system that includes electrically operated solenoid-actuated valves for controlling certain fluid pressures. In accordance with this electric/hydraulic control system, the automatic transmission would be "responsive" to an acceleration factor for controlling the output torque of the transmission during a shift from one ratio of rotation (between the input and output shafts of the transmission) to another. Specifically, the operation of the solenoid-actuated valves would cause a rotational speed versus time curve of a sensed rotational component of the transmission to substantially follow along a predetermined path during shifting. It is one object of the present invention to provide a valve assembly for controlling fluid flow in a four-speed automatic transmission design which can be readily utilized in conjunction with a variety of engines and vehicle sizes and types, including vehicles presently using conventional, mechanical-hydraulic automatic transmission systems. It is another object of the present invention to provide solenoid-actuated valves which directly control fluid flow to their respective clutch assemblies. It is a more specific of the present invention to provide solenoid-actuated valves having a non-close clearance capability to prevent contaminants from inhibiting these solenoid-actuated valves from achieving either their normal or solenoid-actuated position. It is a more specific object of the present invention to provide solenoid-actuated valves with a configuration which allow more efficient operation, such as an armature means with an offset portion toward an electromagnetic means for more efficient magnetic flow. This application is one of several applications filed on the same date, all commonly assigned. According to the invention, the objects referred to above are solved by the features of claim 1. The transmission system according to the present invention is designed to provide limited operation in the absence of electrical power. For example, the arrangement and structure of the solenoid-actuated valves in the hydraulic circuit enable a limp-home mode of operation, which will permit the vehicle to operate in park, neutral, second or reverse gear as desired in the absence of electrical power. With respect to the solenoid-actuated valves used in this transmission system, these solenoid-actuated valves have been designed to be direct-acting and have a non-close clearance design to prevent dirt or other contaminants from interfering with the operation of these valves. Additionally, the solenoid-actuated valves include an armature means having an offset portion extending toward an electromagnetic means to cause a gap between the armature means and the electromagnetic means to be offset toward the center inside the electromagnetic means for efficient magnetic flow. Brief Description Of The Drawings Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiment, the appended claims and in the accompanying drawings in which: Fig. 1 is a cross-sectional view of the normally vented solenoid-actuated valve 632 according to the invention; Fig. 2 is a cross-sectional view of the normally applied solenoid-actuated valve 630 according to the invention; and Fig. 3 is a partial sectional view of the valve of Fig. 2 with a noise-reducing device. Advantageously, the present invention provides direct-acting, non-close clearance solenoid-actuated valves, namely solenoid-actuated valves 630, 632, 634 and 636. The solenoid-actuated valves 630, 632, 634 and 636 directly control fluid flow to their respective clutch assemblies. Since the solenoid-actuated valves 630, 632, 634 and 636 have a non-close clearance design to be described herein, dirt and other contaminants do not inhibit these solenoid-actuated valves from achieving either their normal or solenoid-actuated position. Additionally, these solenoid-actuated valves 630, 632, 634, 636 are designed to provide a limp-home mode of operation. Referring to Figure, a manifold assembly 700 is shown. The manifold assembly 700 houses or contains the solenoid-actuated valves 630, 632, 634 and 636. A cover member 702 is secured by suitable fastening means, such as a screw and washer assembly, to a manifold housing 701. A circuit and switch assembly 752 along with two perimeter seals are sandwiched between the cover member 702 and manifold housing 701. Referring to Figure 1, the overdrive clutch solenoid-actuated valve 632, which is normally vented, is shown and is identical to the low/reverse clutch solenoid-actuated valve 636. The solenoid which actuates valve 632 includes a stationary core member 706 having an outer cylindrical shape. A threaded portion 707 extends from one end of the core member 706 and is threadably engageable with the manifold housing 701. An electrical coil assembly 710 is disposed coaxially around the core member 706. A movable member or armature 712 is spaced axially from the core member 706 to form a working air gap 714 therebetween. An L-shaped magnetic shunt member 715 is secured between the core member 706 and the manifold housing 701. One edge 716 of the shunt member 715 contacts or abuts the armature 712 to allow the armature 712 to pivot or hinge about that line while efficiently transmitting the magnetic flux through the armature 712 and shunt member 715. A plurality of blades 717 are connected one end of the electrical coil assembly 710 and extend outwardly therefrom. The blades 717 are removably disposed in corresponding biased slots 718 in the circuit and switch assembly 752. A bowed or wave spring 719 is disposed between the shunt member 715 and the coil assembly 710 to bias or cause the blades 717 of the electrical coil assembly 710 to fully engage the slots 718 in the circuit and switch assembly 752. This prevents the electrical contact surfaces between the blades 717 and slots 718 from moving or vibrating which may cause excessive wear of these contact surfaces. Additionally, in conjunction with a cylindrical offset portion 712a of the armature 712, this coil position causes the working air gap 714 to be offset toward the center inside of the coil assembly 710, resulting in a more efficient magnetic flow. Also, resistors 713 are connected to the circuit and switch assembly 752 and will be described subsequently. A non-magnetic spacer 719a is disposed between the shunt member 715 and core member 706. The outside diameter of the spacer 719a is larger than the diameter of the core member 706 to avoid magnetic bridging due to fine magnetic debris in the system. The spacer center is configured to retain on a corresponding undercut of the core member 706 and on a projection 708 connected to threaded portion 707 to enhance handling and to prevent the projection 708 from contacting radially the shunt member 715 through the corresponding hole in the shunt member 715. The other end of the armature 712 has an adjustment screw 720 threadably engaged and, in turn, capable of contacting the spherical end 722 of a valve plunger 724, so that the valve plunger 724 will reciprocate in response to appropriate magnetically induced actuations of the armature 712. The adjustment screw 720 is welded to armature 712 after factory setting is established to prevent further thread movement. The adjustment of the screw 720 establishes the working air gap 714 (typically 0.05 to 0.20mm) with all parts in the actuated or energized position such that: full force is available at the valve seat; there is allowance for valve wear; noise of armature 712 striking core member 706 is avoided; smell debris in the working air gap 714 does not cause malfunction; and consistent pull-in and drop-out characteristics are maintained. The valve plunger 724 is formed with a conical portion 725 which, when the solenoid is energized, is shown to be in sealing engagement with a valve insert 726, thereby closing a vent port 727 leading to the vent reservoir 628. The valve insert 726 is disposed in a passageway 728 which communicates between an inlet or supply port 730 and a clutch or element port 732 leading to a clutch apply cavity. Filters or screens 731 and 733 are disposed in the supply port 730 and clutch port 732, respectively, to filter or trap large debris (such as machining chips) and prevent its distribution through the hydraulic system where it could cause malfunction. A movable ball 734 is disposed between a localized, non-sealing travel stop 736 in the passageway 728 and a seat 738 on the valve insert 726. The valve plunger 724 is coaxially disposed within a central passage 740 formed in the valve insert 726 which communicates with the passageway 728, vent port 727 and the clutch port 732. As shown in Figure 1, the valve plunger 724 has a fluted central portion 724a which supports valve plunger 724 concentrically in the central passage 740, yet permits fluid to flow readily through the central passage 740 around the valve plunger 724. Conventionally, the transmission shift control valve member is typically a spool type valve having lands and being reciprocal between lands of a housing. The diametrical clearance between the lands of the conventional valve member and housing range from .0002 to .001 inches (5·10⁻⁶m to 2.5·10⁻⁵m), resulting in potential sticking or jamming by small debris. The present invention utilizes a ball 734 in an oversized passageway 728 to allow an open flow path around the ball 734 during actuation or operation. Hence, close clearances are not required between the ball 734 and passageway 728. In fact, momentarily during the valve ball movement from one seat to the other, the present invention allows a burst of fluid flow from supply port 730 to vent port 727 which flushes the passages. Additionally, the circuit and switch assembly 752 includes an insulative circuit housing 753 disposed between the cover member 702 and the manifold housing 701. A male plug member 754 is connected to the circuit housing 753 for attachment to an external source of electrical power such as a transmission controller. In operation, the overdrive clutch solenoid-actuated valve 632 is normally vented when not energized (i.e. no current flows through the windings of the coil assembly 710). As a result, fluid enters the inlet port 730 and flows through the passageway 728, causing the ball 734 to move and engage the seat 738 of the valve insert 726. The ball 734 on its seat 738 blocks fluid flow from the inlet port 730, preventing fluid from entering clutch port 732. The displacement of the ball 734 moves the valve plunger 724, causing the conical portion 725 to be disengaged or moved off the valve insert 726. As a result, fluid from the clutch port 732 flows through the central passage 740 along the plunger flutes 724a and between the conical portion 725 and valve insert 726, venting through vent port 727 to the vent reservoir 628. Hence, the overdrive clutch solenoid-actuated valve 632 and its related clutch assembly are normally vented. When the overdrive clutch solenoid-actuated valve 632 is actuated, as shown in Figure 1, current flows through the coil assembly 710 and creates a magnetic flux loop through the armature member 712, core member 706 and shunt member 715. This magnetic flux causes a magnetic attraction between the armature 712, shunt member 715 and the core member 706. This causes the armature 712 to move toward and contact the edge 716 of the shunt member 715 to reduce the working air gap 714, but not contact the core member 706. The armature 712 pivots about the edge 716 of the shunt member 715 and displaces the valve plunger 724, and in turn, displaces the ball 734 off the seat 738 to allow fluid to flow from the inlet port 730 past the ball 734 by way of passage 740 through the valve insert 726 to the clutch port 732. Simultaneously, fluid also momentarily flows out vent port 727, producing a cleansing flush of conical portion 725. The motion of armature 712 continues to drive valve plunger 724 until conical portion 725 engages the surface of valve insert 726, thereby closing vent port 727 and preventing continued fluid flow from clutch port 732 into vent reservoir 628 and thereby causing clutch pressure to increase toward the level of inlet pressure. By appropriate time-cycling of the current in coil 710, these valve ports will reciprocate rapidly and provide effective control of the pressure in clutch port 732 at any desired level between that of vent reservoir 628 and fluid flow from inlet port 730. As partially illustrated in Figure 2, the underdrive clutch 630 and two/four shift clutch 634 solenoid-actuated valves are normally applied when not energized or no curent flows through the windings of the coil assembly 710. Prime numerals are used for parts similar to the overdrive clutch solenoid-actuated valve 632 of Figure 1. As a result, fluid enters the inlet or supply port 730' and flows in the passageway 728', causing the ball 734' to move and engage its seat 738' of the two piece valve insert 726'. When the ball 734' is on or engaging the seat 738', a small gap 739 exists between the ball 734' and another ball seat 737. As a result, fluid flows in the gap 739 past the ball 734' and to the clutch port 732'. By engaging seat 738', the ball 734' prevents fluid flow from exiting clutch port 727' via passage 740' and into the vent reservoir 628. Hence, the solenoid-actuated valves 630 and 634 and their related transmission clutch assemblies are normally applied, When the underdrive clutch solenoid-actuated valve 630 is actuated, the armature 712 pivots and displaces the valve plunger 724', and in turn, displaces the ball 734' to engage seat 737. As a result, fluid flow from the supply port 730' is blocked by the ball 734' and is prevented from flowing to the clutch port 732'. Fluid flow from the clutch port 732' is allowed to flow between the ball 734' and seat 738' and through central passage 740', venting through vent port 727' to the vent reservoir 628. As with the normally vented valves, clutch pressure may be regulated by time-cycling the valve. As illustrated in Figure 3, the present invention provides a means for reducing noise resulting from solenoid valve action. A spool 742 having a generally cylindrical shape is disposed in the passageway 728. The spool 742 can slide in the passageway 728. The spool 742 has an axially projecting portion 744 extending into the central passage 740 of the valve seat 726. The projecting portion 744 contacts the ball 734. The spool 742 includes a chamber 745 and an aperture 746 extending axially through the projecting portion 744, both of which allow fluid flow through the spool 742. A spring 747 is disposed within the chamber 745 and biases or lightly loads the spool 742 toward the ball 734. In other words, the spring 747 biases the projecting portion 744 into contact with the ball 734 so that the ball 734 contacts its seat 738. One end of the aperture 746 is closed by the ball 734 during Pull-in or energizing of the coil assembly 710. During de-energization of the coil assembly 710 (i.e. during drop-out), the ball 734 will return freely, opening the aperture 746 and allowing the chamber 745 to refill rapidly so that the next pull-in can be cushioned. The spool 742 also includes a first or supply end land 748 at one end which is slightly smaller in diameter than the passageway 728. Land 748 allows only gradual flow of fluid out of a trapped cavity between land 748 and the manifold housing 701 in passageway 728, thereby slowing pull-in velocity and reducing impact noise. The spool 742 further includes a second or element end land 749 at the other end which is fluted for free flow of fluid. In operation, during pull-in, the ball 734 moves axially, resulting in axial movement of the spool 742. Land 748 allows only gradual flow of fluid past it out of the trapped cavity between land 748 and the manifold housing 701 in the passageway 728. This gradual flow slows the pull-in velocity of the ball 734 and related valve plunger 724 (See Figures 1 and 2), reducing impact noise with the valve seat 726. During drop-out, the ball 734 returns freely allowing the chamber 745 to refill rapidly so that the next pull-in can be cushioned. Also, spring 747 will return the spool 742 so that the projecting portion 744 once again contacts ball 734 to rest the ball 734 on its seat 738. The spool 742 may be used with both normally applied and normally vented solenoid-actuated valves.

Claims: A valve assembly (632) for controlling fluid flow between a fluid supply source and fluid actuating device in a vehicle transmission, said assembly comprising: a housing (701) having a supply port (730) for connection with a fluid supply source, an element port (732) for connection with the fluid actuating device, and a passageway (728) communicating with said supply port (730) and said element port (732); a valve insert (726) disposed in said passageway (728) and having at least two valve seats (727, 738) and a central passage (740) communicating therethrough; a ball (734) disposed within said passageway (728) and cooperating with one valve seat (738) such as to connect or disconnect the element port (732) and the supply port (730); a plunger (724) having a longitudinal axis aligned with the center of said ball (734) to move said ball and having one end contacting said ball (734) and said plunger having on the other end a conical portion (725) cooperating with said second valve seat such as to connect or disconnect the element port (732) and a vent port (727); electromagnetic means (706, 710) for producing a magnetic field when electrically energized; and armature means (712) moveable in response to the presence and absence of a magnetic field for actuating said plunger (724), characterized by armature means (712) having an offset portion (712a) extending toward the electromagnetic means (706,710) to cause a gap (714) between the armature means and electromagnetic means to be offset toward the center inside the electromagnetic means for more efficient magnetic flow and further characterized by said plunger (724) including a plurality of flutes (724a) circumferentially spaced thereabout to maintain alignment of said plunger member in said central passage (740) of said valve insert (726) while allowing fluid flow along said flutes through said central passage (740). An assembly as set forth in claim 1 further characterized by said electromagnetic means comprising a core member (706) secured to said housing (701), and an electrical coil (710) disposed about said core member. An assembly as set forth in claim 2, wherein said armature means (712) comprises an armature member (712) axially spaced from said core member to form a working air gap therebetween. An assembly as set forth in claim 3 including a shunt member (715) disposed between said core member (706) and said housing (701) and contacting said armature member (712) at one edge thereof to allow said armature member to pivot about said edge thereof. An assembly as set forth in claim 4 including a spacer (719a) being non-magnetic disposed between said core member (706) and said shunt member (715), said spacer having a diameter greater than the diameter of said core member (706) to avoid magnetic binding due to fine magnetic debris. An assembly as set forth in one of claims 1 to 5, including contact means (717, 718) for providing an electrical connection between said electrical coil (710) and a circuit means, wherein said contact means comprises at least one male member (717) connected to said electrical coil (710) and a female member (718) connected to said circuit means, said male member being disposed in said female member. An assembly as set forth in claim 6, including spring means (719) for biasing said male member (717) into contact with said female member (718). An assembly as set forth in claim 7, wherein said spring means comprises a spring (719) disposed between said shunt member (715) and said electrical coil (710). An assembly as set forth in one of claims 1 to 8, further characterized by said conical portion (725) having a head portion (722) to contact said armature member (712). An assembly as set forth in one of claims 1 to 9, including a pair of filters (731,733), each of said pair of filters being disposed in said element port (732) and said supply port (730) for filtering contaminants from the fluid flow.

Inventors: KLOTZ JAMES R, NOGLE THOMAS D, KLOTZ, JAMES R., NOGLE, THOMAS D.
Applicants: CHRYSLER CORP, CHRYSLER CORPORATION
Application year: 1989
Main classification: F16K31
IPC codes: F16H61