Claims
- 1. A variable camshaft timing system in combination with an internal combustion engine having a rotatable member such as a crankshaft, an intake camshaft and an exhaust camshaft, the system comprising:
- at least one pulley wheel means fixedly attached to each of the intake camshaft, the exhaust camshaft and the crankshaft;
- at least one belt means for interconnecting various ones of said pulley wheel means;
- first and second idler arm means independently pivotally attached to the engine, each of said idler arm means having a pivoting arm, a cam follower means and an idler wheel in operative contact with said at least one belt means; and
- positioning means operatively coupled to said cam follower means for pivoting said first and second idler arm means and in turn relatively rotating one of said pulley wheel means attached to the intake camshaft with respect to another of said pulley wheel means attached to the exhaust camshaft and for maintaining a predetermined tension in said at least one belt means as said first and second idler arm means are being pivoted.
- 2. A variable camshaft timing system for an internal combustion engine according to claim 1 wherein said at least one belt means is a chain.
- 3. A variable camshaft timing system for an internal combustion engine according to claim 1 wherein said idler wheel on said first idler arm means is positioned in operative contact with said at least one belt means between said pulley wheel means attached to the intake camshaft and said pulley wheel means attached to the exhaust camshaft and said idler wheel on said second idler arm means is positioned in operative contact with said at least one belt means between said pulley wheel means attached to the intake camshaft and said pulley wheel means attached to the crankshaft.
- 4. A variable camshaft timing system for an internal combustion engine according to claim 1 wherein said idler wheel on said first idler arm means is positioned in operative contact with said at least one belt means between said pulley wheel means attached to the intake camshaft and said pulley wheel means attached to the exhaust camshaft and said idler wheel on said second idler arm means is positioned in operative contact with said at least one belt means between said pulley wheel means attached to the exhaust camshaft and said pulley wheel means attached to the crankshaft.
- 5. A variable camshaft timing system for an internal combustion engine according to claim 1 wherein one of said first and second idler arm means has an adjustment means for taking up slack in said at least one belt means.
- 6. A variable camshaft timing system for an internal combustion engine according to claim 1 wherein said positioning means operatively coupled to each of said cam follower means of said idler arm means comprises a first cam means for pivoting said first idler arm means and a second cam means for pivoting said second idler arm means, each of said idler arm means being operable for different rotational movements in response to said positioning means.
- 7. A variable camshaft timing system for an internal combustion engine according to claim 6 wherein said first cam means is operative for relatively rotating the intake camshaft with respect to the exhaust camshaft and said second cam means is operative to maintain a predetermined tension in said at least one belt means.
- 8. A variable camshaft timing system for an internal combustion engine according to claim 6 wherein said first cam means is operative to control the amount of wrap of said belt means around said pulley on said intake camshaft.
- 9. A variable camshaft timing system for an internal combustion engine according to claim 1 additionally including:
- control means responsive to various engine operating parameters for generating motor control signals; and
- motor means responsive to said motor control signals and operatively coupled to said positioning means for changing the relative rotational position between the input camshaft and the exhaust camshaft.
- 10. A variable camshaft timing system for an internal combustion engine according to claim 9 wherein said motor means is an electric stepper motor and said motor control signals operate to step the armature of said motor and said positioning means through an angular position for changing the relative rotational position between the input camshaft and the exhaust camshaft.
- 11. A variable camshaft timing system for an internal combustion engine according to claim 9 wherein said motor means is an electric motor.
- 12. A variable camshaft timing system for an internal combustion engine according to claim 9 wherein said control means includes an electronic control unit having a plurality of sensor means each responsive to one of a plurality of engine operating parameters.
- 13. A variable camshaft timing system for an internal combustion engine according to claim 12 wherein said electronic control unit additionally includes a look-up means responsive to said engine operating parameters for generating said motor control signals.
Parent Case Info
This application is a continuation of prior complete application Ser. No. 017,670 filed on Feb. 24, 1987, now U.S. Pat. No. 4,744,338.
US Referenced Citations (3)
Foreign Referenced Citations (3)
Number |
Date |
Country |
59-63338 |
Apr 1984 |
JPX |
651109 |
Aug 1985 |
CHX |
2088471 |
Jun 1982 |
GBX |
Non-Patent Literature Citations (2)
Entry |
Patent Abstracts of Japan, vol. 8, No. 166 (M-314)(1603) 8/1984. |
Patent Abstracts of Japan, vol. 10, No. 109 (M0472)(2166) 4/1986. |
Continuations (1)
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Number |
Date |
Country |
Parent |
17670 |
Feb 1987 |
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