PRE-EMPTIVE ELECTROMAGNETIC CLUTCH APPLY SYSTEM t CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a PCT International Application of United States Patent Application No. 60/927,082 filed on May 1 , 2007. The disclosure of the above application is incorporated herein by reference.

FIELD OF THE INVENTION

The present relates to the actuation of clutches, more particularly, the actuation of clutches through the use of an electromagnetic solenoid.

BACKGROUND OF THE INVENTION

Clutch assemblies which have an electromagnetic clutch apply system are generally known. It is quite common to use clutches which have an electromagnetic apply system or a hydraulic apply system in an all-wheel drive, or four-wheel drive vehicle. Typically, the types of clutches which have an electromagnetic apply system include using a solenoid with some other device to actuate a clutch pack which transfers torque from an input member to an output member. One of the main problems with current clutch activation systems is a delay which occurs from the time at which the clutch activation is commanded, and the time at which torque transfer begins to occur. It is considered desirable to have torque transfer occur the instant the solenoid is actuated (i.e. pre-emptive apply), thereby causing torque transfer to occur in a substantially instantaneous manner.

Accordingly, there exists a need for an improved actuation of a clutch assembly in a four-wheel drive or all-wheel drive vehicle which eliminates this delay.

SUMMARY OF THE INVENTION

The present invention uses a solenoid to directly apply a wet clutch system for providing a pre-emptive actuation function used with either a four- wheel drive or all-wheel drive coupling, or on-demand transfer case system.

The present invention is a clutch assembly which includes an input member, an output member selectively connected to the input member, a clutch pack, an actuation plate having at least one arm which is disposed along the clutch pack, and a solenoid actuator operably associated with the actuation plate. When the solenoid actuator is activated, the actuation plate will be drawn toward the solenoid actuator, causing the arm to compress the clutch pack, forcing the input member and the output member to rotate together.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

Figure 1 is a sectional view of a clutch pack actuated by a solenoid according to the present invention; Figure 2 is a sectional side view of a clutch pack actuated by a solenoid actuator, according to the present invention; and

Figure 3 is a sectional front view of a solenoid actuator and an actuation plate taken along 3-3 of Figure 2, according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

The clutch assembly 10 includes an input member 12 selectably connected to an output member 14. The input member 12 has a shaft 16 which includes a series of threads 18 and splines 20. The splines 20 engage a series of corresponding splines 22 on a flange 24. The flange 24 has a series of apertures 26 which can be used to connect the flange 24 and

thereby the clutch assembly 10 to a shaft providing input power. The flange 24 is secured to the input member 12 through the use of a retaining nut 28 which also includes a series of corresponding threads 30 which are received by the threads 18 on the input member 12. The clutch assembly 10 also includes a housing 32 which has multiple protrusions 34 which are used to attach the clutch assembly 10 to a transmission, differential, or transfer case, depending upon the particular application in which the clutch assembly 10 is to be used. Located in between the housing 32 and the flange 24 is a seal 36 which is used to prevent fluid leakage from the clutch assembly 10. Another seal 38, in the form of an O- ring seal, is located near the protrusions 34 for also preventing leakage out of the housing 32, when the clutch assembly 10 is connected to another device.

The input member 12 is supported by a roller bearing 40; the roller bearing 40 is located between the flange 24 and housing 32, and allows the input member 12 and flange 24 to rotate freely therein. The output member 14 is supported by and rotates on annular seals 42 and a thrust bearing 44 located between the input member 12 and the output member 14, and allows relative rotation therebetween.

Also included as part of the input member 12 is bell-shaped member 46. Bell-shaped member 46 has a recess 48 for receiving a snap-ring 50; the snap-ring 50 supports an end plate 52, which in turn supports a collar 54. The collar 54 has a series of outer splines 56 which are engaged with a series of corresponding splines 60 on bell-shaped member 46. An annular seal 58 in the form of an O-ring seal is also provided to prevent fluid leakage between the bell-shaped member 46 and the collar 54. The collar 54 also supports the annular seal 42, which allows for relative motion between the collar 54 and the output member 14.

Positioned within the bell-shaped member 46 is a clutch pack 62. The clutch pack 62 has a first series of clutch plates 66 interleaved with a second series of clutch plates 68. The first series of clutch plates 66 have splines 70 on their outer diameter which engage with the splines 60 on the bell-shaped member 46, which causes the first series of clutch plates 66 to rotate with the bell-shaped member 46. The second series of clutch plates 68 have splines

72 on their inner diameter which engage with complementary splines 74 on output member 14.

To actuate the clutch assembly 10, housing 32 also includes an solenoid actuator 76. The solenoid actuator 76 includes an electromagnetic coil 78 and an annular housing 80 secured to the housing 32 by a plurality of fasteners such as the screw 82 and nut 84 shown in Figure 1. The annular housing 80 is generally U-shaped and surrounds the electromagnetic coil 78. The solenoid actuator 76 also includes a conductor cable 86 which is used to energize the solenoid actuator 76 and activate the actuation plate 88. The actuation plate 88 also has a plurality of arms 90 which extend through a plurality of corresponding apertures 92, and around the first clutch pack 62. The arms 90 also include seals 94, here in the form of O-ring seals, to prevent fluid leakage through the apertures 92. The arms 90 also have an extension 95, which extends around the clutch pack 62. Located between the actuation plate 88 and the annular housing 80 is an air gap 96. The air gap 96 allows the actuation plate 88 and arms 90 to rotate with the bell-shaped member 46, without contacting the solenoid actuator 76.

The clutch pack 62 is a wet clutch, where fluid provides cooling and lubrication and is retained in the clutch assembly 10 by the seals 36, 42, 58, and 94. Oil is fed to the clutch pack 62 through the oil feed tubes 98.

In operation, electric power is applied to the solenoid actuator 76 through the conductor cable 86. This causes the actuation plate 88 to be drawn toward the solenoid actuator 76, thereby also drawing the arms 90 toward the solenoid actuator 76 as well. As this occurs, the extensions 95 on the arms 90 will compress the clutch pack 62.

The load transferred through the clutch assembly 10 flows initially through the flange 24 and through splines 20 and to the corresponding splines 22 on the input member 14. This forces the bell-shaped member 46 to rotate as well. The load is then transferred through the clutch pack 62. More specifically, the load is then transferred from the splines 60 to the splines 70 on the first series of clutch plates 66. The frictional engagement between the first series of clutch plates 66 and the second series of clutch plates 68

transfers the load to the second series of clutch plates 68, to the splines 72, the splines 74 and to the output member 14.

The output member 14 has a series of splines 100 which can be engaged to any shaft having complementary splines, and requires rotation through the use of clutch assembly 10.

The engagement of the clutch pack 62 through the use of the solenoid actuator 76 and the extensions 95 of the arms 90 provide the advantage of having a reduction in response time compared to conventional clutches which are actuated by another type of actuation. The advantage with the present invention is that the solenoid actuator 76 provides an essentially instantaneous compression of the clutch pack 62, providing instantaneous torque transfer between the input member 12 and the output member 14.

This type of actuation improves performance when used in a four-wheel drive, or all-wheel drive vehicle. The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.