Title:
Linear cam valve system
Kind Code:
A1


Abstract:
This invention relates to a linear cam valve operating system consisting of a linear cam and follower/tappet installed in a carrier and directly connected to a driving means such as an electro-magnetic or similar type apparatus using a reciprocating or shuttle type driving action with the linear cam action actuating the intake and exhaust valves of an internal combustion engine. Timing of the valve action is controlled from the driving mechanism with valve movement determined by the linear cam using a direct or combined direct-conjugate profile.



Inventors:
Scott, Robert Taylor (Alpharetta, GA, US)
Application Number:
10/862180
Publication Date:
01/27/2005
Filing Date:
06/07/2004
Assignee:
SCOTT ROBERT TAYLOR
Primary Class:
International Classes:
F01L1/04; F01L1/14; F01L1/30; (IPC1-7): F01L1/04
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Primary Examiner:
RIDDLE, KYLE M
Attorney, Agent or Firm:
ROBERT T. SCOTT (Alpharetta, GA, US)
Claims:
1. A linear cam system driven by a means using a reciprocating or shuttle type action with said driver connected to a linear cam acting on a follower/tappet which actuates the intake and exhaust valves of an internal combustion engine.

2. The linear cam system described in claim 1 is comprised of a linear cam connected to a companion follower/tappet installed in a carrier housing making up a cam unit or module and attached transversely to the engine at a point between the linear cam driving mechanism and the engine intake and exhaust valves.

3. The linear cam described in claim 2 has profiles shaped to achieve specific or controlled valve movement.

4. The linear cam described in claim 2 has combined direct-conjugate profiles and is used with a two way driver to power the engine valves to the open position by the action of the direct cam profile and to the closed position by the action of the conjugate profile supplemented by light spring tension on the engine intake and exhaust valves.

5. The linear cam described in claim 2 is used with a one way driver providing the opening valve action by the direct cam profile with return or closing action provided by spring tension on the driver and engine valves.

6. The linear cam described in claim 2 has a constant rectangular shaped cross section running the length of the cam.

7. The linear cam described in claim 2 has a rectangular shaped cross section in the center of the cam accommodating the direct-conjugate profiles and cylindrical shaped cross sections on the ends of the cam providing mating surfaces with the cam carrier.

8. The carrier housing described in claim 2 contains one or more linear cams and one or more follower/tappets making up a cam unit or module.

9. The linear cam described in claim 1, is installed directly on the actuating mechanism of the driving device.

10. The linear cam unit described in claim 2 is attached to the cylinder head on overhead valve engines.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims all rights and priorities under provisional patent application No. 60/489,873 filed Jul. 25, 2003.

BACKGROUND OF THE INVENTION

This invention relates to a linear cam directly connected to a driving means such as an electromagnetic or other type apparatus using a reciprocating or shuttle type driving action with the linear cam actuating the intake and exhaust valves of an internal combustion engine.

Rotating camshafts with elliptical lobes have been used to operate intake and exhaust valves since the early development of the internal combustion engine. This technology, over 100 years old, is the current standard valve operating system for internal combustion engines using the poppet valve system. No prior art relating to a linear cam valve system could be located.

Fuel economy and air pollution concerns associated with the internal combustion engine have led to the development of computer technology to control the valve timing and action of this type engine. The present approach to valve systems is the camless engine which involves directly connecting the standard poppet valve to either an electromagnetic or electro-hydraulic driver device and using computer technology to time and control the valve action. Numerous patents relating to camless engines have been filed with the majority relating to electromagnetic drivers. As of this time there are no successful engines marketed using a camless system.

Problems associated with the electro-magnetic/hydraulic systems include:

The energy required for operation of the driver.

The operating force required from the driver to open the engine valves, particularly the exhaust valve, as it is under both spring and combustion pressure.

The electro-magnetic driver will meet the speed requirements of high RPM engines but has high energy requirements. The electro-hydraulic system has limitations on operating speed.

The electro-magnetic driver is noisy and creates wear on the valve and seats as valves are slammed shut very briskly.

With both type drivers engine height becomes an issue as the drivers are mounted vertically or at slight angles on the top of the engine.

Patents addressing some of these points are: U.S. Pat. No. 4,794,890 Richeson—U.S. Pat. No. 5,690,064 Izuo—U.S. Pat. No. 6,539,901 Nishida—U.S. Pat. No. 6,557,506 Sturman.

BRIEF SUMMARY OF THE INVENTION

This invention utilizes a linear cam connected to a reciprocating or shuttle action driver to actuate the intake and exhaust valves of an internal combustion engine. The objective of this invention is a valve actuating system that reduces the power requirements for operation of same and uses a linear cam profiled to share valve timing and control with a companion driver mechanism. The background information discusses technology other than a linear cam system. However, the linear cam improves or solves most of the problems related to the use of electro-magnetic/hydraulic valve systems.

The improvements provided by this invention include:

The linear cam can be configured for valve movement as well as power requirements.

Less powerful units can be used.

Soft landing valve closure can be profiled in the cam.

Resting points at open or closed positions are suitable for valve deactivation as well as energy savings.

The reciprocating back and forth action is well suited to a computer controlled on/off driving mechanism.

The linear cam unit and driver are transversely mounted on the engine utilizing side space of the engine compartment. Engine compartments generally have more available side space than top space.

The linear cam can be configured with a direct profile or as a combined direct and conjugate profile providing positive action for both the upward and downward valve movement. This permits the use of low tension valve springs thereby effecting energy savings and reducing noise.

While the linear cam profile can be incorporated into the operating mechanism of the driver device, a separate unit consisting of the carrier, cam, and cam follower/tappet lowers manufacturing costs and makes the unit easily adaptable to present engine and valve designs as well as current driver technology.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 Cam unit module with connecting surfaces for the engine and driver.

FIG. 2 Two piece cam unit housing with direct/conjugate profile linear cam.

FIG. 3 Follower/tappet and pin.

FIG. 4 Flat rectangular shaped linear cam 2 with direct-conjugate profile.

FIG. 5 Cylindrical shaped linear cam 2A with flat rectangular center section and direct/conjugate profile.

REFERENCE NUMBERS

1—cam carrier.

2—flat rectangular linear cam.

2A—cylindrical linear cam with rectangular center section.

3—follower/tappet for use with combined direct and conjugate profile linear cam using a clevis or similar type connection.

4—tappet pin/roller.

5—driver.

6—engine.

7—engine poppet valve.

8—engine poppet valve spring.

DETAILED DESCRIPTION OF THE INVENTION

While there are numerous valve and engine configurations, this description and drawings will be limited to one cam unit/module and engine valve to describe the linear cam system. The linear cam replaces the presently used lobed cam with the driving means supplied by an electromagnetic, electro-hydraulic or other type driver using a reciprocating or shuttle type movement rather than a rotating camshaft. This permits engine valve action and timing to be shared by a computer controlled driver connected to a linear cam rather than under total cam mechanical control. The sliding linear cam is housed in a carrier and attached to the engine over the exposed end of the poppet valve. The driver is a separate unit attached to the cam carrier with the driving means connected to the linear cam. The two separate units operating together; driver unit and linear cam unit make up the valve operating system for the engine. Few modifications are necessary to adapt the system to current overhead valve engine designs.

Electro-magnetic, electro-hydraulic or similar drivers have powered one way or two way movements. Movements of the driver may be computer controlled. The linear cam has features that are desirable for use with an on/off or stop and go driver. These include:

The high and low points (open/close) can have resting positions requiring very little power to hold the position. This feature can be utilized to realize power savings and valve deactivation.

The linear cam can be profiled in similar fashion to a rotating cam. This permits some cam control of power required to operate the cam determined by length of cam movement combined with the cam profile.

Soft landing or valve closure can also be profiled into the cam. This profile would also reduce the energy required to open the valve. Specifically, the exhaust valve, as it opens against both spring and combustion pressure.

The linear cam is easily configured as a combined direct and conjugate cam by using a slotted arrangement with parallel profiles.

FIG. 1 represents a cam unit/module consisting of the cam carrier (1), direct-conjugate profile linear cam(2), and follower/tappet (3) attached transversely to the engine (6). The driver (5) is attached to the carrier (1) and connected to the linear cam (2) which operates in a reciprocating fashion on the roller/pin (4) acting on cam follower/tappet (3) which in turn raises or lowers the engine valve (7). The opening movement of the cam is against the spring tension (8) of the engine valve and combustion pressure in the case of the exhaust valve. Combustion pressure has little effect on intake valve operation. Closure of the engine valve under spring tension occurs on the reverse movement of the linear cam. The above description outlines cam and valve action using a one way driver with the direct cam profile acting on the tappet through roller pin (4) actuating a spring tensioned poppet valve, the standard valve type used in current engine designs. The conjugate profile is not involved as the valve is closed by spring tension. If desired, the linear cam used with a one way driver would not require a conjugate profile. Further description of the conjugate profile follows in paragraph [0044].

FIG. 2 shows the cam carrier (1) as a two piece unit consisting of a top and bottom section fastened together with mountings for the driver and engine attachment. The preferred carrier would be a one piece unit. However, two sections can be used if necessary for machining or other manufacturing considerations.

FIG. 3 shows the follower/tappet (3) and connecting pin/roller (4) used with the linear cam. The follower/tappet is connected to the linear cam (2 or 2A) by the pin/roller (4) positioned in the slotted cam. The lower end of the tappet can be free or secured to the engine valve. The description in paragraph [0042] would use the tappet free on the lower end where return or closure action is handled by spring tension on the driver and engine valve. Securing the tappet to the engine valve (7) and using a two way driver powers the follower/tappet and valve in both directions. The direct profile of the linear cam opens the valve with closure effected by the conjugate profile thus powering the engine valve up and down reducing spring tension required for the engine valves. Sufficient operating clearances are provided to accommodate proper valve seating. Modem engines operating at high RPM require heavy tension valve springs to prevent valve float or failure to close. The two way driver eliminates valve float and permits lighter spring tension on the valves.

FIG. 4 shows the linear cam (2) as a rectangular solid piece with combined direct-conjugate profiles. The cam can also be of cylindrical shape (2A) with a flat rectangular center section as shown in FIG. 5. Both views show a combined direct-conjugate profile. As discussed in paragraph [0042] the cam can be manufactured with only a direct profile if used with a one way driver. However, the combined direct-conjugate configuration can be used with either a one way or two way driver.

The movement of the linear cam as described in paragraph [0042] is the same for both the one way and two way driver. The cam and valves are spring returned when using a one way driver and power returned supplemented by light spring tension when using a two way driver. As the linear cam moves to the closed position by either powered or spring tension, the valve movement is guided or controlled by the roller pin (4) positioned against the profile of the linear cam. A soft landing or closure is profiled into the cam. Opening and closing valve movement would be similar to movement produced by a rotating cam.

The described linear cam system is adaptable to current engine and poppet valve designs. A one way driving device utilizing the direct cam profile and a spring tensioned return would require few modifications for current engine and valve designs. Use of a two way driver would require securing valve stems to the tappet.

The described invention incorporates the profile features of a rotating cam into a linear cam with the driver controlling the valve timing, duration and deactivation. Valve timing and control is shared by the driver and linear cam. While the preceding description relates to poppet valves, the linear cam can be used with any type engine valve operated by a back and forth movement.

The present invention is disclosed according to the preferred embodiments. However, it should be understood that changes could be introduced by those skilled in the art without departing from the scope of the invention. The scope of the invention is limited only as defined in the following listed claims.