Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
1999-08-27
2001-03-13
Walberg, Teresa (Department: 3742)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
Reexamination Certificate
active
06199522
ABSTRACT:
FIELD OF INVENTION
This invention relates to a valve train of an internal combustion engine and, more particularly, concerns a device for varying the timing of the opening and closing of the intake and/or exhaust valves with respect to the phase of the piston stroke.
BACKGROUND OF THE INVENTION
Applicant's U.S. Pat. No. 5,673,659 entitled “Lead Screw Driven Shaft Phase Control Mechanism”, issued on Oct. 7, 1997 and assigned to the assignee of this invention, discloses a mechanism that provides a selective timing or phase adjusting system between a drive gear and a driven camshaft with the drive gear being coaxially mounted and axially affixed with respect to the driven camshaft for rotation together. An intermediate connecting member is coaxially mounted with respect to the drive gear and the camshaft and is capable of axial movement and angular movement with respect to either the camshaft or the drive gear when experiencing its relative axial movement. The intermediate connection and a coupling member are connected to a geared device that is selectively activated by an electric motor which produces axial movement of both the intermediate connection and the coupling member with respect to the camshaft and the drive gear to any desired axial position between predetermined first and second positions. The gearing device provides a unidirectional drive system which allows the electric control motor to drive the mechanism to provide the optimum shaft phasing and is operably connected to a sleeve that is axially affixed to the intermediate connecting member. When in operation, the gearing device moves the sleeve axially, which in turn, moves the intermediate member axially with respect to both the drive gear and the camshaft. The intermediate connection member is an axially shifting member that has helical splines that rotationally affix it to the camshaft to allow relative rotation of the camshaft with respect to the drive gear. In one embodiment, the gearing device drives the sleeve while in another embodiment the gearing device is a threaded lead screw engaging complementary threads formed on the sleeve. In a third embodiment disclosed in the patent, the gearing device is a part of a gear sprocket that has an internally threaded hub that engages complementary external threads on the sleeve.
In my U.S. Pat. No. 5,860,328 entitled “SHAFT PHASE CONTROL MECHANISM WITH AN AXIALLY SHIFTABLE SPLINED MEMBER”, which issued Jan. 19, 1999 and assigned to the assignee of this invention, I disclose a two part variable valve timing system. In my co-pending patent application, Ser. No. 09/283,019, entitled “TWO PART VARIABLE VALVE TIMING MECHANISM”, filed on Apr. 1, 1999 and assigned to the assignee of this invention, I disclose a new form of power transmission that is substituted for the threaded jackscrew system which executes the axial motion of the shifting sleeve. Inasmuch as the lowest possible friction level is desired in camshaft phase controlling devices to minimize wear and to allow use of a small electric motor for varying the position of the camshaft, it is important to have a transmission arrangement with less friction than an ACME screw. The optimum replacement for an ACME screw would be a ball-nut recirculating screw device which enjoys very low friction in operation. However, irrespective of the many advantages provided by such a device, using it for a camshaft phase controlling mechanism is not possible from a practical standpoint because the required ball-return duct would interfere with the drive gear. Accordingly, in each of the devices covered by the above-mentioned patent applications, I have incorporated into the mechanisms one of the ball-nut transmissions disclosed in my co-pending patent application, Ser. No. 09/271,229, entitled “BALL-NUT TRANSMISSION”, filed on Mar. 17, 1999, and assigned to the assignee of this invention. In my co-pending DaimlerChrysler File No. 99-1420 patent application, the disclosed device differs from the device shown in my Ser. No. 09/283,019, in that the splined connection between the camshaft and the quill shaft, rather than being grouped together at one end or the other of the device are, instead, separated so that the helical spline connection is incorporated with the control assembly and the straight spline connection is incorporated with the timing drive assembly.
SUMMARY OF THE INVENTION
The present invention has one similarity to each of the devices disclosed in my aforementioned co-pending patent applications (DaimlerChrysler File Nos. 99-1419 and 99-1420) in that each device includes a form of the ball-nut transmission disclosed in my above-mentioned co-pending patent application (Ser. No. 09/271,229). However, this invention differs from each of those devices in that the quill shaft has one end rigidly connected to the drive gear while the other end of the quill shaft is formed with helical splines which act through a unique connecting member that couples helical splines encircling straight splines for providing a phase change of the camshaft relative to the drive gear of the drive assembly.
Stated broadly, the camshaft phase controlling device made in accordance with the present invention is intended for use with an internal combustion engine and includes a timing drive assembly located at one end of the engine and a control assembly located at the other end of the engine. The timing drive assembly has a drive gear adapted to be driven by the crankshaft of the engine and has a hollow camshaft that extends between the timing drive assembly and the control assembly. A quill shaft is coaxially mounted within the hollow camshaft and has a first portion located at the aforementioned one end of the engine that is connected directly to the drive gear. The quill shaft has a second portion located at the aforementioned other end of the engine and is formed at the other end with a plurality of helical splines. The hollow camshaft is formed with a cylindrical extension encircling the helical splines of the quill shaft and has its inner cylindrical surface formed with straight splines extending along the longitudinal axis of the hollow camshaft. In addition, an axially movable sleeve member surrounds the cylindrical extension of the hollow camshaft and is connected with a cylindrical connector member located between the helical splines and the straight splines. A plurality of equally circumferentially spaced pins are supported by the connector member and each of the pins serve to interconnect the helical splines with the straight splines. A nut member surrounds the sleeve member and is drivingly connected to the sleeve member through a plurality of circumferentially spaced non-recirculating balls encapsulated in the sleeve member and located in a helical groove formed in the nut member. The arrangement is such that, upon rotation of the nut member, the sleeve member and the interconnected connector member are moved axially to cause the pins to move axially along the helical splines and the straight splines to provide a phase change of the camshaft relative to the drive gear.
One object of the present invention is to provide a new and improved camshaft phase controlling device that is provided with two major parts one of which is located at the front end of an internal combustion engine and the other is located at the rear end of the engine and in which the control assembly of the device incorporates a ball-nut transmission for providing linear movement of a slidable connector member which interacts with straight splines of the camshaft and with helical splines formed on a quill shaft for changing the phase of a the camshaft.
Another object of the present invention is to provide a new and improved camshaft phase controlling device which has a quill shaft extending through a hollow camshaft and has one end of the quill shaft directly connected to the drive gear with the other end of the quill shaft formed with helical splines that are connected through a connector member to straight splines formed on the inside diameter of the hollow cams
DaimlerChrysler Corporation
MacLean Kenneth H.
Patel Vinod
Walberg Teresa
LandOfFree
Camshaft phase controlling device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Camshaft phase controlling device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Camshaft phase controlling device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2473314