Crank angle detection apparatus

A crank angle detection apparatus may include a crank gear provided to be rotated together with a crankshaft, a balance gear provided to be rotated together with a balance shaft and engaged with the crank gear so that the balance shaft is rotated in accordance with rotation of the crankshaft, and a crank angle sensor configured to sense rotation of the balance gear or the crank gear and detect a rotation angle of the crankshaft.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority of Korean Patent Application Number 10-2012-0155368 filed Dec. 27, 2012, the entire contents of which application are incorporated herein for all purposes by this reference.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a crank angle detection apparatus, and more particularly, to a crank angle detection apparatus in which a separate target wheel for detecting a crank angle is omitted.

2. Description of Related Art

In general, a crank angle sensor refers to a sensor which detects a rotation angle or a rotation position of a crankshaft of an engine.

The rotation angle (crank angle) of the crankshaft is an important parameter that determines ignition timing of the engine. For detecting a crank angle using the crank angle sensor, there are a method of directly detecting a rotation angle of the crankshaft and a method of estimating the crank angle from a rotation position of a distributor. Here, the distributor is a device for distributing high voltages generated in an ignition coil to spark plugs in order of ignition.

A method of detecting a signal from the distributor connected to an electric system is simple, but precision thereof is low. Therefore, a method of directly detecting a crank angle is mainly used in recent years.

However, if a separate target wheel, which is subject to detection by the crank angle sensor, is mounted at the crankshaft to directly detect the crank angle, a size and a weight of an engine may be increased. In addition, as processes of manufacturing the target wheel and mounting the target wheel at the crankshaft are added, the number of production processes for the engine may be increased. Moreover, components for mounting the target wheel at the crankshaft are required. Therefore, production costs for the engine may be ultimately increased.

SUMMARY OF INVENTION

The present invention has been made in an effort to provide a crank angle detection apparatus in which an additional constituent element for detecting a crank angle is not required.

In addition, the present invention has been made in an effort to provide a crank angle detection apparatus having advantages of reducing a size and a weight of an engine, simplifying a production process, and reducing production costs.

Various aspects of the present invention provide a crank angle detection apparatus including a crank gear provided to be rotated together with a crankshaft, a balance gear provided to be rotated together with a balance shaft and engaged with the crank gear so that the balance shaft is rotated in accordance with a rotation of the crankshaft, and a crank angle sensor configured to sense a rotation of the balance gear and detect a rotation angle of the crankshaft.

The crank gear may include a protrusion that protrudes from an outer circumference of the crank gear, and the balance gear may include a groove that is concavely recessed from an outer circumference of the balance gear, wherein the protrusion and the groove are disposed to be engaged with each other in accordance with the rotations of the crank gear and the balance gear.

The crank angle sensor may be disposed to detect a position of the groove, may sense a position of the balance gear in accordance with the position of the groove, and may detect a rotation angle of the crankshaft.

The crank angle sensor may be disposed to monitor a position where the protrusion and the groove are engaged with each other, may sense the rotation of the balance gear in accordance with a period when the protrusion and the groove are engaged with each other, and may detect a rotation angle of the crankshaft.

A ratio of the number of protrusions to the number of grooves may be the same as a gear ratio of the crank gear to the balance gear. The protrusion and the groove may have shapes corresponding to each other.

Various other aspects of the present invention provide a crank angle detection apparatus including a crank gear provided to be rotated together with a crankshaft, a balance gear provided to be rotated together with a balance shaft and engaged with the crank gear so that the balance shaft is rotated in accordance with a rotation of the crankshaft, and a crank angle sensor configured to sense a rotation of the crank gear and detect a rotation angle of the crankshaft.

The crank gear may include a groove that is concavely recessed from an outer circumference of the crank gear, and the balance gear may include a protrusion that protrudes from an outer circumference of the balance gear, wherein the groove and the protrusion are disposed to be engaged with each other in accordance with the rotations of the crank gear and the balance gear.

The crank angle sensor may be disposed to detect a position of the groove, may sense a position of the crank gear in accordance with the position of the groove, and may detect a rotation angle of the crankshaft.

The crank angle sensor may be disposed to monitor a position where the groove and the protrusion are engaged with each other, may sense the rotation of the crank gear in accordance with a period when the groove and the protrusion are engaged with each other, and may detect a rotation angle of the crankshaft.

A ratio of the number of grooves to the number of protrusions may be the same as a gear ratio of the crank gear to the balance gear. The groove and the protrusion may have shapes corresponding to each other.

DETAILED DESCRIPTION

FIG. 1is a configuration view of a crank angle detection apparatus according to various embodiments of the present invention. As illustrated inFIG. 1, a crank angle detection apparatus of the present invention includes a crankshaft10, a balance shaft20, a crank gear15, a balance gear25, and a crank angle sensor30.

The crankshaft10refers to an apparatus which is installed in a crank case, and outputs force to the outside of an engine by receiving force of a piston, which is transmitted by an explosion stroke of each cylinder. In addition, the crankshaft10converts reciprocating motion of the piston into rotational motion, and outputs torque. Meanwhile, the piston reciprocates in accordance with rotational motion of the crankshaft10in suction, compression, and exhaust strokes of each of the cylinders. Here, the crankshaft10and the piston are connected to each other by a connecting rod. In addition, the crank case is integrally formed with a cylinder block, or separately formed to be coupled to the cylinder block.

The crankshaft10includes a balance weight12, and a crank pin14. The balance weight12is formed to adjust weight balance when the crankshaft10is rotated. In addition, the balance weight12provides additional rotational inertia for the crankshaft10.

The crank pin14is rotatably connected to a connecting rod, and connects the connecting rod and the balance weight12. That is, the crank pin14is coupled to a big end of the connecting rod. In addition, the balance weight12may be formed at both ends of the crank pin14.

The balance shaft20is mounted in the engine in which the piston reciprocates. In addition, the balance shaft20is mounted to generate a load in a direction in which inertial force or forces, which is/are generated by reciprocating motion of the piston and rotational motion of the crankshaft10, is/are attenuated. Moreover, one or two balance shafts20are used in accordance with the number or arrangement of cylinders of the engine, and are rotated in the same direction as or a reverse direction to the crankshaft at a speed, for example, equal to or two times of a speed of the crankshaft.

The configurations and the operations of the crankshaft10and the balance shaft20are known in the art, and therefore a more detailed description will be omitted.

The crank gear15refers to a gear provided at the crankshaft10so that the crankshaft10and the balance shaft20are engaged with each other. In addition, the crank gear15is rotated together with the crankshaft10. Moreover, the crank gear15is formed in a circular shape like a general gear, and gear teeth are formed on an outer circumference of the crank gear15.

The balance gear25refers to a gear provided at the balance shaft20so that the crankshaft10and the balance shaft20are engaged with each other. In addition, the balance gear25is rotated together with the balance shaft20. Moreover, the balance gear25is formed in a circular shape like a general gear, and gear teeth are formed on an outer circumference of the balance gear25.

The gear teeth of the crank gear15and the gear teeth of the balance gear25are engaged with each other. That is, because the balance gear25and the crank gear15are engaged with each other, the balance shaft20is rotated in accordance with the rotation of the crankshaft10.

Meanwhile, in a two-cylinder engine, a general gear ratio of the crank gear15to the balance gear25is 1:1. In addition, in a four-cylinder engine, a general gear ratio of the crank gear15to the balance gear25is 2:1.

WhileFIGS. 1 to 3illustrate a state in which the crank gear15and the balance gear25are directly engaged with each other, the crank gear15and the balance gear25may be connected by an additional gear to be rotated in the same direction as or a reverse direction to each other. This connection between the crank gear15and the balance gear25may be readily changed and applied, and is within the spirit and scope of the present invention.

The crank angle sensor30refers to a sensor which detects a rotation angle of the crankshaft10. In addition, the crank gear15or the balance gear25is subject to detection by the crank angle sensor30. That is, the crank angle sensor30detects the rotation angle of the crankshaft10by sensing rotation of the crank gear15or the balance gear25. Moreover, the crank angle sensor30is mounted on the cylinder block. Meanwhile, the crank angle sensor30is disposed at a position on the cylinder block, where the crank angle sensor30may sense the rotation of the crank gear15or the balance gear25.

FIG. 2illustrates the crank gear and the balance gear according to various embodiments of the present invention. As an example,FIG. 2illustrates the crank gear15and the balance gear25of a two-cylinder engine.

As illustrated inFIG. 2, the crank gear15and the balance gear25of the two-cylinder engine have a gear ratio of 1:1. In addition, the crank gear15includes a protrusion17, and the balance gear25includes a groove27.

The protrusion17is formed on an outer circumference of the crank gear15. In addition, the protrusion17is a portion protruding from the outer circumference of the crank gear15. That is, the protrusion17is formed at a part of the outer circumference of the crank gear15, where the gear teeth are omitted.

The groove27is formed on an outer circumference of the balance gear25. In addition, the groove27is a portion concavely recessed from the outer circumference of the balance gear25. That is, the groove27is formed at a part of the outer circumference of the balance gear25, where the gear teeth are omitted.

FIG. 2illustrates a state in which a single protrusion17is formed at the crank gear15, and a single groove27is formed in the balance gear25. However, the present invention is not limited thereto, and the numbers and the shapes of the protrusions17and the grooves27may be readily changed and applied. In addition, a ratio of the number of protrusions17to the number of grooves27is 1:1, which is the same as the gear ratio of the crank gear15to the balance gear25. Moreover, the groove27may be formed in the crank gear15, and the protrusion17may be formed at the balance gear25. Meanwhile, the protrusion17and the groove27have shapes corresponding to each other.

In a case in which the single protrusion17and the single groove27are formed at the crank gear15and the balance gear25, respectively, the protrusion17and the groove27may be engaged with each other once for every one rotation of the crank gear15and the balance gear25. The above-mentioned operation is possible because the gear ratio of the crank gear15to the balance gear25of the two-cylinder engine is formed to be 1:1. In addition, the crank gear15and the balance gear25are disposed such that the protrusion17and the groove27are engaged with each other in accordance with the rotation of the crank gear15and the balance gear25.

The crank angle sensor30may be disposed so as to observe, monitor or detect a position where the protrusion17and the groove27are engaged with each other.

In a case in which the crank angle sensor30is disposed so as to observe, monitor or detect the position where the protrusion17and the groove27are engaged with each other, the crank angle sensor30senses rotation of the crank gear15or the balance gear25in accordance with a period when the protrusion17and the groove27are engaged with each other, and detects a rotation angle of the crankshaft10.

The crank angle sensor30may be disposed so as to detect a position of the protrusion17or the groove27.

In a case in which the crank angle sensor30is disposed so as to detect the position of the protrusion17or the groove27, the crank angle sensor30senses a position of the crank gear15or the balance gear25in accordance with the position of the protrusion17or the groove27, and detects a rotation angle of the crankshaft10.

FIG. 3is a view illustrating a crank gear and a balance gear according to various embodiments of the present invention. In addition,FIG. 3illustrates the crank gear15and the balance gear25of the four-cylinder engine.

As illustrated inFIG. 3, the crank gear15and the balance gear25of the four-cylinder engine have a gear ratio of 2:1. In addition, the crank gear15includes grooves19, and the balance gear25includes a protrusion29.

The grooves19are formed on an outer circumference of the crank gear15. In addition, the grooves19are portions concavely recessed from the outer circumference of the crank gear15. That is, the grooves19are formed at parts of the outer circumference of the crank gear15, where the gear teeth are omitted.

The protrusion29is formed on an outer circumference of the balance gear25. In addition, the protrusion29is a portion protruding from the outer circumference of the balance gear25. That is, the protrusion29is formed at a part of the outer circumference of the balance gear25, where the gear teeth are omitted.

FIG. 3illustrates a state in which the two grooves19are formed at the crank gear15, and the single protrusion29is formed at the balance gear25. However, the present invention is not limited thereto, two protrusions29may be formed at the crank gear15, and a single groove19may be formed at the balance gear25. In addition, the numbers and the shapes of the grooves19and the protrusions29may be changed and applied by the person skilled in the art. Moreover, a ratio of the number of grooves19or protrusions29formed at the crank gear15to the number of grooves19or protrusions29formed at the balance gear25is 2:1, which is the same as the gear ratio of the crank gear15to the balance gear25. Meanwhile, the grooves19and the protrusion29have shapes corresponding to each other.

In a case in which two grooves19are formed at the crank gear15, and one protrusion29is formed at the balance gear25, the protrusion29may be alternately engaged with the two grooves19of the crank gear15for every one rotation of the balance gear25. That is, the protrusion29, which has been engaged with one of the two grooves19, is engaged with the other of the two grooves19after next one rotation of the balance gear25. The above-mentioned operation is possible because the gear ratio of the crank gear15and the balance gear25of the four-cylinder engine is formed to be 2:1, and the two grooves19are formed to be symmetric with respect to a rotation center of the crank gear15. In addition, the crank gear15and the balance gear25are disposed such that the grooves19and the protrusion29are engaged with each other in accordance with the rotation of the crank gear15and the balance gear25.

The crank angle sensor30may be disposed so as to observe, monitor or detect a position where the grooves19and the protrusion29are engaged with each other. In a case in which the crank angle sensor30is disposed so as to observe, monitor or detect the position where the grooves19and the protrusion29are engaged with each other, the crank angle sensor30senses rotation of the crank gear15or the balance gear25in accordance with a period when the grooves19and the protrusion29are engaged with each other, and detects a rotation angle of the crankshaft10.

The crank angle sensor30may be disposed so as to detect a position of the grooves19or the protrusion29. In a case in which the crank angle sensor30is disposed so as to detect the position of the grooves19or the protrusion29, the crank angle sensor30senses a position of the crank gear15or the balance gear25in accordance with the position of the grooves19or the protrusion29, and detects a rotation angle of the crankshaft10.

According to various embodiments of the present invention described above, a separate target wheel for sensing a crank angle is omitted, the crank angle sensor30directly detects a crank angle using the crank gear15or the balance gear25, which are required to connect the crankshaft10and the balance shaft20, and as a result, a size and a weight of an engine may be reduced. In addition, a production process for the engine may be simplified. Moreover, production costs of the engine may be reduced.