JP2011089477A - Torque compensation device for camshaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To absorb torque fluctuation accompanying valve open and close generated on a camshaft of an internal combustion engine by using magnetic force. <P>SOLUTION: A rotary member 1 is fixed as one body on the camshaft 5 including a cam 6 and a driven sprocket 7, and a fixed member 9 fixed on an engine body is disposed oppositely to the rotary member. Magnets 2, 3 are disposed on the rotary member 1 and the fixed member 9 respectively and the torque fluctuation by the cam of the camshaft 5 is absorbed by repulsion force or attraction of the magnets. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a torque compensator that compensates for torque fluctuations acting on a camshaft of an internal combustion engine such as a gasoline engine or a diesel engine.

  In general, an internal combustion engine transmits rotation of a crankshaft to a camshaft by a timing chain or a timing belt, and opens and closes an intake valve and an exhaust valve by a cam provided on the camshaft to supply a mixed gas into the cylinder. In addition, waste gas is discharged from the cylinder. Since the camshaft operates the intake or exhaust valve against the spring, a large torque fluctuation occurs during one rotation (one cycle).

  The above-mentioned timing chain often causes the life of the internal combustion engine and the overhaul time, and is required to have high fatigue strength, high wear resistance and quietness, and the wear environment such as direct injection of the engine is It is expected to become even more severe. Further, low friction is also required from the viewpoint of improving fuel consumption and reducing exhaust gas.

  Roller chains and silent chains are used as the above timing chains, and chain manufacturers strive to improve their durability and lower friction by improving their materials and shapes, as well as systems including tensioners. However, it is also conceivable to reduce the torque fluctuation of the camshaft, reduce the tension load acting on the timing chain, and improve the life of the timing chain and thus the internal combustion engine.

  2. Description of the Related Art Conventionally, a cam shaft torque compensation device described in Patent Document 1 has been proposed. A torque pulse (torque fluctuation) is generated on the camshaft when the cam operates the valve against or in sequence with respect to the spring. However, the torque compensator reverses the torque pulse generated by the cam. A cam having another phase is provided, and the torque fluctuation of the cam that actually operates the valve is canceled by a torque pulse that rotates against the spring or sequentially.

JP-A-4-272551

  The camshaft torque compensation device presses a cam follower biased by a spring against a cam that is different from the cam that operates the valve, so that the friction increases and the cam follower interlocked with the torque compensation cam. The undesired torque is generated by the acceleration motion. For this reason, in the torque compensator, in order to absorb the torque fluctuation of the camshaft of the internal combustion engine rotating at a relatively high speed, an energy loss is generated due to the increase of the friction, and an extra torque due to inertia is generated. The camshaft torque compensation device cannot exhibit sufficient performance.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a camshaft torque compensator that solves the above-mentioned problems by absorbing torque fluctuations of the camshaft using magnetic force.

The present invention comprises a rotating member (1) that rotates in conjunction with a camshaft (5) of an internal combustion engine,
A fixing member (9) arranged close to the rotating member;
The rotating member and the fixed member are provided with magnets (2) and (3) arranged so as to cancel torque fluctuation caused by the cam (6) of the cam shaft opening and closing the valve.
It is in the camshaft torque compensation device.

  The magnet includes a permanent magnet and an electromagnet, and further includes a magnetic body that generates a magnetic force with another magnet.

The camshaft (5) is provided with a driven sprocket (7), and the rotation of the crankshaft is transmitted to the driven sprocket via a timing chain,
The rotating member (1) is provided integrally with the driven sprocket (7).

  The magnets (2, 3) are permanent magnets.

  The magnets (2, 3) are electromagnets.

For example, referring to FIG. 5, one of the rotating member (1) and the fixing member (9) is an integral two members,
The other of the rotating member and the fixing member is a middle member disposed between the two members,
The magnet is arranged on a side surface of the two members facing the middle member,
The magnet is arranged on both surfaces of the middle member facing the two members.

  The two members may be disk-like members arranged at intervals in the axial direction or drum-like members arranged at intervals in the radial direction. It may be a disk-shaped member disposed between the disk-shaped members or a drum-shaped member disposed between the two drum-shaped members.

  For example, referring to FIG. 7, the magnets arranged on the rotating member or the fixing member are arranged adjacent to each other on the side facing the N pole and the S pole, and the fixing member or the magnet facing the magnet is arranged. A closed magnetic circuit is formed with the magnet of the rotating member.

  In addition, although the code | symbol in the said parenthesis is for contrast with drawing, it does not have any influence on the structure as described in a claim by this.

  According to the first aspect of the present invention, it is possible to reduce the torque fluctuation by compensating the torque fluctuation caused by opening and closing the valve acting on the camshaft by a magnetic force, and reducing the maximum torque transmitted to the camshaft. The load of the power transmission device to the camshaft can be reduced.

  Further, since the torque compensator is based on magnetic force, it does not come into contact with each other, there is no energy loss due to friction, and aging does not occur, and a reciprocating motion mechanism like a conventional torque compensator using a cam and a spring. Therefore, there is little influence on the torque generated by the compensator due to the rotational speed of the camshaft, and it functions effectively as a torque compensator for the camshaft of the engine.

  According to the second aspect of the present invention, since the tension load of the timing chain for transmitting power to the camshaft is reduced, it is advantageous for the fatigue strength of the timing chain, and the wear elongation is reduced. In addition to improving durability, the durability of the timing chain system including the tensioner and vibration damper can be improved, and the life limit until engine overhaul can be extended.

  It also reduces friction due to the bending of the timing chain, guides and tensioners, etc., reduces the size of the timing chain itself and sprocket, and adopts a silent chain with high transmission efficiency, reducing energy loss associated with transmission. Also, it can contribute to improvement of fuel efficiency and quietness of the engine.

  According to the third aspect of the present invention, since the attractive force or repulsive force of the permanent magnet is used, the structure is simple, inexpensive and compact.

  According to the fourth aspect of the present invention, it is possible to absorb the torque fluctuation of the camshaft with high accuracy by adjusting the magnitude and timing of the generated torque using an electromagnet, for example, by vector control or the like.

  According to the fifth aspect of the present invention, the rotating member and the fixed member are constituted by the two integral members and the middle member positioned therebetween, so that the thrust force of the magnet that generates the compensation torque is canceled out. Thus, it is possible to prevent the occurrence of friction in the bearing or the like due to the thrust force.

  According to the sixth aspect of the present invention, since the closed magnetic circuit is formed between the magnets facing each other, magnetic leakage is small and torque compensation by the magnet can be performed with high efficiency.

It is a figure which shows the basics of the torque compensation apparatus which concerns on this invention, (a) is a front view which shows the state which rotated the rotating member, (b) is a figure which shows the torque fluctuation of the 1 cycle. (A) is a perspective view which shows the outline of the torque compensation apparatus of the cam shaft by this invention, (b) is a figure which shows the torque. (A) is a figure which shows the generated torque in a test apparatus, (b) is a figure which shows the state which applied the torque compensation apparatus to the internal combustion engine. (A)-(e) is a side view which shows the different combination of the magnet of a torque compensation apparatus. (A)-(f) is a side view which shows the combination of a different magnet by three discs. The figure which shows embodiment which has arrange | positioned four magnets to the disc. The side view which shows embodiment from which arrangement | positioning of a magnet differs. The front view which shows embodiment using an electromagnet. The front view which shows embodiment using a centrifugal force.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the principle of a camshaft compensation device using magnets will be described with reference to FIG. A permanent magnet 2 is fixed to one place in the circumferential direction of a rotating member (rotary disc, rotor) 1 fixed to the camshaft, and one permanent magnet 3 is attached to a fixing member (stator) facing the rotating member 1. Fix it. The two permanent magnets are arranged so that the same poles face each other, and are configured to repel each other.

  When the rotating member 1 rotates together with the cam shaft and the rotating-side permanent magnet 2 approaches the fixed-side permanent magnet 3, both magnets repel each other, load the rotating member 1 with torque, and load ( On the contrary, the torque gradually increases as the rotating permanent magnet 2 approaches the fixed permanent magnet 3, and becomes maximum when the overlapping amount of both magnets is halved, and gradually decreases as the overlapping amount increases. Become. When the two magnets face each other (completely overlap), the torque due to the repulsive force becomes zero, and when the rotating member 1 rotates beyond the opposite position, the repulsive forces of the two magnets 2 and 3 are A torque in a direction that assists the rotation of the rotating member 1 is generated. The assist (forward) torque gradually increases as the amount of overlap between the two magnets decreases, the amount of overlap reaches a maximum at ½, and then gradually decreases as the rotating side magnet 2 moves away from the fixed side magnet 3. .

  That is, when the rotating side magnet 2 approaches, opposes, and moves away from the fixed side magnet 3, a torque consisting of an approximate sine curve is applied to one cycle of the camshaft, as shown in FIG. Helped. The camshaft is acted on by a torque consisting of an approximate sine curve to operate the valve against the spring, so that the torque from the magnet is at the timing to cancel the torque from the actual cam operation. Is set. The explanation of the above principle in FIG. 1 is intended to be applied to a single-cylinder engine using DOHC (double, overhead cam) using one rotating permanent magnet and one fixed permanent magnet. However, when applied to an in-line four-cylinder engine, four permanent magnets are arranged at equiangular (90 degrees) intervals on the rotating member (rotor) of the camshaft, and four fixed side permanent magnets are also equiangularly spaced. Be placed. In the case of SOHC (single, overhead cam), an intake valve cam and an exhaust valve cam are formed on one cam shaft, and the two magnets are arranged so as to cancel the operation of the two cams. Therefore, the present invention can also be applied to a SOHC camshaft.

  FIG. 2 is a diagram showing an outline of an embodiment in which the torque compensation device for the camshaft is applied to a DOHC system of a one-cylinder engine. A cam 6 is formed on the cam shaft 5 and a driven sprocket 7 is fixed integrally therewith. Rotation from the engine crankshaft is transmitted to the driven sprocket 7 after being reduced to ½ through a timing chain (not shown). A drum-shaped rotating member 1 is fixed to a side surface of the driven sprocket 7. The rotating member 1 is made of a nonmagnetic material, and a permanent magnet 2 is fixed to one place on the inner peripheral surface of the rotating member. On the other hand, a drum-shaped fixing member 9 is integrally fixed to the engine body, which is a fixing member. The fixing member 9 is made of a non-magnetic material, and the permanent magnet 3 is fixed to one place on the outer peripheral surface of the fixing member. ing.

  The rotating member 1 and the fixed member 9 are arranged concentrically and overlap each other in a side view, and the rotating side magnet 2 and the fixed side magnet 3 are arranged so that the same poles face each other. For example, when the rotation side magnet 2 has an S pole on the inner circumference and an N pole on the outer circumference, the fixed magnet 3 has an S pole on the outer circumference and an N pole on the inner circumference. In the figure, reference numeral 10 denotes a cam follower which contacts and follows the peripheral surface of the cam 6 and operates the valve in the open position against the spring, and operates the valve in the closed position in accordance with the spring. The magnets 2 and 3 are arranged so as to cancel the torque fluctuation of the cam shaft 5 caused by the cam 6.

  Accordingly, the cam 6 is rotated by the rotation of the cam shaft 5 accompanying the engine rotation, and the valve is opened and closed by the cam follower 10 including the rocker arm, the push rod and the like. At this time, as shown in FIG. 2B, the camshaft 5 receives the fluctuation torque C by the valve spring, but the compensation torque D by the magnets 2 and 3 acts in the opposite direction to the fluctuation torque C, The input torque E of the shaft 5 is a leveled value with small fluctuation. As a result, the input torque E of the camshaft 5 through the timing chain, particularly its maximum value, is reduced, and the durability of the timing chain is improved. In addition, the chain tension by the downsizing of the timing chain, the tensioner, the vibration damper, and the like can be reduced, thereby reducing the loss and contributing to the improvement of the engine fuel consumption. Furthermore, it is possible to employ a silent chain having a higher transmission efficiency than the roller chain for the timing chain, thereby improving fuel efficiency and chain durability. Furthermore, since the torque compensator uses a rotating side magnet and a stationary side magnet that are spaced apart from each other, friction does not occur and friction loss does not occur.

  The rotating member 1 and the fixed member 9 were tested with a test apparatus in which four discs having an outer diameter of 60 [mm] and four neodymium magnets arranged at an equal angle (90 degrees) on the outer periphery thereof were tested. The magnets are 15 × 10 × t5 [mm], 4 on each of the fixed side and the rotating side, 8 in total, so that the different poles face each other and the clearance of the magnet is 0.5 [mm] It was arranged so that. Unlike the above description, the magnet produced by the test apparatus uses an attractive force, and the maximum generated torque is 1.8 [N · m].

  FIG. 3 shows a simulation by mounting the torque compensator using the magnet in a 4-cylinder diesel engine (SOHC system 1000 [cc]). FIG. 3A shows the compensation torque generated in the test apparatus, and FIG. 3B shows each torque when it is mounted on the camshaft of the engine. 3A and 3B, the vertical axis represents the torque of the camshaft, and the horizontal axis represents the rotation angle of the crankshaft. Therefore, the rotation angle of the cam shaft is ½ of the horizontal axis.

  The compensation torque by the test device is an approximate sine curve with a maximum of 1.8 [N · m], and the normal cam torque C of the engine in a state where the compensation torque does not act is a maximum of 7.6 [N · m]. ] And consists of an approximate sine curve. In addition, when the compensation torque D is applied, the input torque E of the combined camshaft becomes 5.8 [N · m] at the maximum, and is reduced by 24 [%] compared to the normal cam torque C.

  FIG. 4 is a diagram showing different modes of the magnet, in which one of the left and right is a rotating member, and the other is a fixed member. (A) is arrange | positioned so that a different magnetic pole may face, and generate | occur | produces a compensation torque with an attractive force. (B) is arrange | positioned so that the same pole (for example, N pole) may face each other, and a compensation torque is generated by repulsion of a magnet. In (c), one is a permanent magnet (permanent magnet is expressed as a magnet) and the other is a magnetic body such as iron, and the number of magnets is small. (D) uses an electromagnet and a magnet, and the facing poles may be the same or different. In (e), an electromagnet is disposed on one side and a magnetic body is disposed on the other side. In FIG. 4, disks are used on the rotating side and the fixed side, and both magnets (or magnetic bodies) face each other in the axial direction. For example, as shown in FIG. Of course, both magnets may face each other in the radial direction using a member.

  FIG. 5 is a diagram showing an embodiment using three disks. Two discs on both outer sides are fixed together and connected so as to rotate relative to the middle disc. For example, if both outer disks are on the rotation side, the middle disk is the fixed side, and if both outer disks are on the fixed side, the middle disk is the rotation side. In (a), electromagnets are used for both outer disks, and electromagnets are arranged on both sides of the middle disk. The facing poles may be the same or different. In (b), electromagnets (or magnetic bodies) are disposed on both outer disks, and magnetic bodies (or electromagnets) are disposed on both surfaces of the middle disk. In (c), magnets (or electromagnets) are arranged on both outer disks, and an electromagnet (or magnet) is arranged on the middle disk. In (d), magnets (or magnetic bodies) are disposed on both outer disks, and a magnetic body (or magnet) is disposed on the middle disk. In (e), S poles (or N poles) are arranged on both outer disks, N poles (or S poles) are arranged on both sides of the middle disk, and a compensation torque is generated by the attractive force of the magnet. In (f), the S pole (or N pole) is arranged on one of the outer circular plates, the N pole (S pole) is arranged on the other, and the S pole (or N pole) is arranged on one side of the middle disc. The N pole (or S pole) is arranged on the other side surface. That is, it is arranged on the side where the same poles face each other, and a compensation torque is generated by the repulsive force of the magnet.

  By using the three discs, the thrust load generated in the magnetic force is canceled out and does not act on the rotating member, and the friction generated in the bearing or the like due to the thrust force can be eliminated. FIG. 5 shows an embodiment in which the rotating member and the fixed member are discs and the magnetic poles face in the axial direction. However, the rotating member and the fixed member are in a drum shape so that the magnetic poles face in the radial direction. Of course, it may be. For example, a drum-shaped rotating member is fixed to a sprocket (see reference numeral 7 in FIG. 2) fixed to the camshaft, and an outer diameter side fixing member and an inner diameter side fixed to the engine body on the outer diameter side and the inner diameter side, respectively. A fixing member is arranged, magnets (or electromagnets, magnetic bodies) are arranged on the outer peripheral surface and inner peripheral surface of the drum-shaped rotating member, respectively, and the outer peripheral surface of the outer diameter side fixing member and the outer peripheral surface of the inner diameter side fixing member are respectively arranged. A magnet (or electromagnet, magnetic body) may be disposed. Alternatively, the fixed side may be a single drum-shaped member, and the rotary drum-shaped members may be disposed on the inner diameter side and the outer diameter side thereof.

  FIG. 6 shows an embodiment in which four magnets 2 are arranged every 90 degrees on the circumference of one rotating member 1. As a result, four cycles of torque fluctuation can be obtained in one rotation. When it is desired to obtain a large compensation torque fluctuation (maximum torque), four magnets are arranged on each of the rotation side and the fixed side, and torque fluctuation due to the attractive force or repulsion force of the four magnets can be obtained. When a large torque is not required, the required compensation torque can be set by using one to three magnets on either the rotating side or the fixed side. Moreover, it is possible to adjust the generated torque curve by arranging which magnets are uneven (positions deviating from 90 degrees).

  FIG. 7 shows an embodiment relating to the arrangement of the magnets. N and S poles are arranged on the magnets facing each other, and one outer disk 11 has an S pole (or N pole) on the outer diameter side and an N pole (or S pole) on the inner diameter side, An N pole (or S pole) is arranged on the outer diameter side of the center disk 12 facing each other, and an S pole (or N pole) is arranged on the inner diameter side. An N pole (or S pole) is arranged on the outer diameter side of the other outer circular plate 13 and an S pole (or N pole) is arranged on the inner diameter side, and the S pole (or N pole) is arranged on the outer diameter side of the middle disc 12 facing it. N pole (or S pole) is arranged on the inner diameter side. Thereby, both the outer side discs 11 and 13 and the middle disc 12 generate | occur | produce attraction | suction force by the different pole which faces on the outer diameter side and inner diameter side, respectively, generate | occur | produce compensation torque, and each disc 11, One magnet of Nos. 12 and 13 has different polarities on the inner diameter side and the outer diameter side, forming a closed magnetic circuit with the facing magnets, and magnetic leakage is small. In addition, although demonstrated with the magnet (permanent magnet), it is natural that it is the same also with an electromagnet, and it is applied similarly also with a drum-shaped member.

  FIG. 8 is a diagram showing an outline of a torque compensator using an electromagnet. The torque compensator has a drum-shaped fixing member 9 fixed to the engine body and a rotating member 1 fixed to the cam shaft 5. The fixing member 9 is provided with iron cores 3a at equal intervals (120 degrees), and the electromagnet 3 is formed by winding a coil 3b around these iron cores. The rotating member 1 is composed of a large number of rectangular laminated plates 1a, and permanent magnets 2 are embedded in the tip portions of these laminated plates. Therefore, the present torque compensator using the electromagnet 3 has the same configuration as the brushless DC motor. In addition, a rotation sensor including a magnetic sensor or the like is provided in the vicinity of the rotation member (not shown), and the rotation position of the rotation member 1 is detected with high accuracy.

  The coils 3b of the three electromagnets 3 are respectively connected to the controller, and these three poles flow alternating currents with a time delay of 1/3 of one rotation, respectively, at intervals of 180 degrees. Torques in the positive and negative directions are applied to the fixed permanent magnets 2 and 2. Based on the detection of the rotational position of the rotating member 1, the controller adjusts the current flowing through each pole at an appropriate timing by, for example, vector control, and applies the torque in the positive direction and the negative direction with the desired timing and magnitude to the rotating member 1. Give. As a result, it is possible to absorb the torque fluctuation of the camshaft 5 and appropriately absorb the torque fluctuation due to the valve inertia based on the difference in the rotational speed of the camshaft.

  FIG. 9 shows a torque compensator that adjusts the magnetic force according to the rotational speed of the camshaft. A drum-shaped fixing member 9 fixed to the engine body and a cylindrical rotating member 1 fixed to the cam shaft 5 are provided. A predetermined number, for example, one permanent magnet 3 is fixed to the inner peripheral surface of the fixing member 9. A hole 15 is formed in the rotating member 1 in the radial direction, and a permanent magnet 2 is fitted in the hole so as to be movable in the radial direction. The magnet is stretched between the cam shaft 5 and the rotating member 1. The spring 16 is biased in the inner diameter direction. A groove 15 a having a predetermined radial length is formed in the hole 15, and a pin 17 fixed to the magnet 3 is fitted into the groove 15, thereby restricting a moving range of the magnet 3.

  Based on the above configuration, in the torque compensator, when the engine is stopped, the rotation of the cam shaft 5 is also stopped, and the rotation side magnet 2 is pulled by the spring 16 and positioned at a position away from the fixed side magnet 3. When the engine rotates and the camshaft 5 rotates, the rotating side magnet 2 also rotates together, and centrifugal force acts on the magnet 2. The rotation-side magnet 2 is set at a position where the centrifugal force and the tension of the spring 16 are balanced. When the rotation of the camshaft 5 is slow, the centrifugal force is small, and the rotation-side magnet 2 is positioned relatively away from the fixed-side magnet 3 due to the spring tension. When the camshaft 5 rotates at a high speed, the centrifugal force acting on the rotating side magnet 2 is large, and the rotating side magnet 2 is positioned closer to the fixed side magnet 3.

  Thus, when the rotation of the camshaft 5 is low, the compensation torque by the magnet is relatively small. However, when the rotation of the camshaft 5 is high and a relatively large valve inertia force acts, compensation is accordingly made. The torque also increases, and the camshaft fluctuation torque can be properly absorbed. The permanent magnets 2 and 3 may be arranged so that the same poles face each other or different poles face each other, and a magnetic material may be placed instead of one permanent magnet.

  In the above description, the rotating member is integrally fixed to the cam shaft. However, the rotating member can be applied to a variable valve mechanism (VVT). In this case, the variable valve is provided between the cam shaft and the driven sprocket. A mechanism is interposed, and the angle between the camshaft and the driven sprocket is variable. Further, the power transmission from the crankshaft to the camshaft is not limited to the timing chain, but can be similarly applied to the transmission using a timing belt or a gear.

DESCRIPTION OF SYMBOLS 1 Rotating member 2 Magnet 3 Magnet 5 Cam shaft 6 Cam 7 Driven sprocket 9 Fixed member

Claims (6)

A rotating member that rotates in conjunction with the camshaft of the internal combustion engine;
A fixing member disposed in proximity to the rotating member;
A magnet disposed on the rotating member and the fixed member so as to cancel torque fluctuation caused by the cam of the camshaft opening and closing the valve;
A torque compensation device for a camshaft. The camshaft is provided with a driven sprocket, and the rotation of the crankshaft is transmitted to the driven sprocket via a timing chain,
The rotating member is provided integrally with the driven sprocket.
The torque compensation device for a camshaft according to claim 1. The magnet is a permanent magnet;
The torque compensation device for a camshaft according to claim 1 or 2. The magnet is an electromagnet;
The torque compensation device for a camshaft according to claim 1 or 2. One of the rotating member and the fixed member is an integral two members,
The other of the rotating member and the fixing member is a middle member disposed between the two members,
The magnet is arranged on a side surface of the two members facing the middle member,
The magnet is disposed on both surfaces of the middle member facing the two members.
The torque compensation device for a camshaft according to any one of claims 1 to 4. A magnet arranged on the rotating member or the fixed member is arranged adjacent to each other on the side facing the north and south poles, and between the magnet of the stationary member or the rotating member facing the magnet. Forming a closed magnetic circuit with
The torque compensation device for a camshaft according to any one of claims 1 to 5.

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