The invention relates generally to an engine system including first and second camshaft phasers.
Engine systems known in the art commonly include a first camshaft, a second camshaft, and a crankshaft. The first camshaft typically has a first camshaft sprocket, the second camshaft typically has a second camshaft sprocket, and the crankshaft typically has a crankshaft sprocket. Engine systems known in the art also commonly include a timing chain coupled to the first camshaft sprocket, the second camshaft sprocket, and the crankshaft sprocket to transmit torque from the crankshaft to the first and second camshafts.
The engine systems known in the art further commonly include first and second camshaft phasers. The first and second camshaft phasers advance or retard the phase of the first and second camshafts relative to the crankshaft. However, when the first and second camshaft phasers advancing or retard the phase of the first and second camshafts relative to the crankshaft, the timing chain between the first and second camshaft phasers may fail to remain under tension. As such, the timing chain may experience undue noise, vibration, and harshness near the first and second camshaft phasers.
As such, there remains a need to provide an improved engine assembly.
An engine system includes a first camshaft, a second camshaft spaced from the first camshaft, a first camshaft phaser coupled to the first camshaft, and a second camshaft phaser coupled to the second camshaft. The first camshaft phaser has a first camshaft sprocket disposed about the first camshaft, and the second camshaft phaser has a second camshaft sprocket disposed about the second camshaft.
The engine system also includes a crankshaft spaced from the first and second camshafts, and a crankshaft sprocket coupled to the crankshaft. The engine system further includes a timing chain coupled to the first camshaft sprocket, the second camshaft sprocket, and the crankshaft sprocket. The timing chain is configured to transmit torque from the crankshaft sprocket to the first and second camshaft sprockets upon rotation of the crankshaft.
The engine system further includes a biasing member extending from a first end portion coupled to the first camshaft phaser to a second end portion coupled to the second camshaft phaser to maintain tension on the timing chain between the first and second camshaft phasers. As such, the timing chain is prevented from generating undue noise, vibration, and harshness near the first and second camshaft phasers.
Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
With reference to the Figures, wherein like numerals indicate like parts throughout the several views, an engine system 10 is shown in
The engine system 10 also includes a crankshaft 24 spaced from the first and second camshafts 12, 14, and a crankshaft sprocket 26 coupled to the crankshaft 24. The engine system 10 further includes a timing chain 28 coupled to the first camshaft sprocket 20, the second camshaft sprocket 22, and the crankshaft sprocket 26. The timing chain 28 is configured to transmit torque from the crankshaft sprocket 26 to the first and second camshaft sprockets 20, 22 upon rotation of the crankshaft 24.
The engine system 10 further includes a biasing member 30 extending from a first end portion 32 coupled to the first camshaft phaser 16 to a second end portion 34 coupled to the second camshaft phaser 18 to maintain tension on the timing chain 28 between the first and second camshaft phasers 16, 18. As such, the timing chain 28 is prevented from generating undue noise, vibration, and harshness near the first and second camshaft phasers 16, 18.
The biasing member 30 may be moveable between an extended position, as shown in
The biasing member 30 may be moveable between the extended position and the compressed position based upon rotational positions of the first and second camshaft sprockets 20, 22 of the first and second camshaft phasers 16, 18. As the crankshaft 24 rotates, the timing chain 28 transmits torque from the crankshaft 24, more specifically the crankshaft sprocket 26, to the first and second camshafts 12, 14 through the first and second camshaft sprockets 20, 22. As the first and second camshaft sprockets 20, 22 rotate, the rotational positions of the first and second camshaft sprockets 20, 22 change. In this way, the biasing member 30 may move between the extended position and the compressed position as a result of the first and second camshaft sprockets 20, 22 rotating. More specifically, the biasing member 30 may be configured to alternate between the extended position and the compressed position upon rotation of the first and second camshaft sprockets 20, 22.
The first end portion 32 of the biasing member 30 may be coupled to the first camshaft sprocket 20 of the first camshaft phaser 16. The first end portion 32 of the biasing member 30 may have a first loop 36 defining a first hole 38. Although not required, the first loop 36 may be an English or German hook, and/or may be completely enclosed or at least partially open. The engine system 10 may further include a first pin 40 disposed through the first hole 38 of the first loop 36 to couple the first end portion 32 of the biasing member 30 to the first camshaft sprocket 20 of the first camshaft phaser 16.
The second end portion 34 of the biasing member 30 may be coupled to the second camshaft sprocket 22 of the second camshaft phaser 18. The second end portion 34 of the biasing member 30 may have a second loop 42 defining a second hole 44. Although not required, the second loop 42 may be an English or German hook, and/or may be completely enclosed or at least partially open. The engine system 10 may further include a second pin 46 disposed through the second hole 44 of the second loop 42 to couple the second end portion 34 of the biasing member 30 to the second camshaft sprocket 22 of the second camshaft phaser 18.
The first pin 40 may be disposed through the first hole 38 of the first loop 36 to couple the first end portion 32 of the biasing member 30 to the first camshaft sprocket 20 of the first camshaft phaser 16 at a first angular location on the first camshaft sprocket 20. The second pin 46 may be disposed through the second hole 44 of the second loop 42 to couple the second end portion 34 of the biasing member 30 to the second camshaft sprocket 22 of the second camshaft phaser 18 at a second angular location on the second camshaft sprocket 22.
The first angular location of the first pin 44 and the second angular location of the second pin 46 may be angularly offset relative to one another. It is to be appreciated, however, that the first angular location of the first pin 44 may be the same as the second angular location of the second pin 46. However, in the embodiments where the first angular location of the first pin 44 and the second angular location of the second pin 46 are angularly offset relative to one another, the first angular location and the second angular location may be angularly offset relative to one another by between 180 and 0 degrees, 150 and 30 degrees, and 120 and 60 degrees. It is also be appreciated that the first angular location and the second angular location may be angularly offset relative to one another by approximately 90 degrees.
Although not required, as shown in
As shown in
The first camshaft phaser 16 may have a first rotor disposed between the first camshaft sprocket 20 and the first camshaft 12. The second camshaft phaser 18 may have a second rotor disposed between the second camshaft sprocket 22 and the second camshaft 14. The first and second rotors may be used to advance or retard the phases of the first and second camshafts 12, 14 relative to the crankshaft 24.
Although not required, the biasing member 30 may be coil spring. It is to be appreciated, however, that the biasing member 30 may be chosen from a variety of springs including, but not limited to, conical springs, barrel springs, magazine springs, tension springs, and helical springs including compression springs and extension springs.
The first camshaft 12 may be further defined as an intake camshaft 48 configured to operate an intake valve. The intake valve selectively allows intake air to enter into a piston in an internal combustion engine. The second camshaft 14 may be further defined as an exhaust camshaft 50 configured to operate an exhaust valve. The exhaust valve selectively allows exhaust gas to exit from the piston in the internal combustion engine. The exhaust camshaft 50 may have a force exerted on it to rotate counterclockwise even without the biasing member 30 present. This force is referred to as a retard bias on the exhaust camshaft 50.
The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings, and the invention may be practiced otherwise than as specifically described.