Abstract
A drive linkage is provided between a drive shaft and a driven shaft, each rotated about a fixed axis. The linkage includes a pair of intermediate gears between the gears concentrically mounted on the drive and driven shafts respectively linked fixing the center to center distances of adjacent gears and maintenance of neighboring gears in driving engagement. The link further includes a pair of gears of control, a primary control gear is maintained in driving engagement with the drive gear through a pivoted link and a gear control related side main drive gear and rotatably mounted to one of the intermediate gear via a pin closely, but displaced from the centers of these gears. Selective positioning of the primary control sprocket causes an oscillation in the intermediate gear engaged with the driven gear, resulting in cyclic accelerations and decelerations in the driven gear responsive to a constant rotation speed in the drive gear. A preferred embodiment this linkage is disclosed in connection with an internal combustion engine of four-stroke cycle.
Description
Background of the InventionThis invention relates to links operable to engage a drive shaft and a driven shaft, and more particularly to a link of causing cyclic accelerations and decelerations controlled on the driven shaft, responsive to the rotation of the drive shaft at a constant speed . A particular embodiment of the invention relates to coupling the drive camshaft internal combustion engine to provide acceleration and deceleration at the camshaft corresponding to the crank motion of the crank shaft and the shaft.Is well known, in connection with four internal combustion engines of conventional two-stroke, the optimum valve timing varies with engine speed. More particularly, the duration during which each of the intake valves and exhaust valves is opened, and the amount of overlap, or the time during which both valves are open, ideally vary with engine speed . Typically, however, the crankshaft and camshaft are linked by a direct drive linkage that fixes the rotation of the camshaft at half times the rate of the speed of the crankshaft. The duration of each valve, constant angular degrees in terms of decreases in real time as the engine speed increases.This leads to the need for a relatively long valve overlap at high engine revolutions. In other words, the intake valve opens before the end of the exhaust stroke and while the exhaust valve is still open, to provide sufficient time for the charge air and fuel to reach the combustion chamber and enter the chamber that creates the piston travels down a lower pressure to draw in office. Similarly at high speed, it is desirable and typical practice for the exhaust valve is opened before the end of the power stroke, either before bottom dead center.Conversely, at low engine speed, especially at idle, it is necessary premature opening of the exhaust valve, and the valve overlap of intake and exhaust is undesirable because it increases the likelihood that part charge of air / fuel is exhausted, and that some of exhaust will be forced backwards towards the carburetor, thus reducing available torque, increase fuel consumption, and increase undesirable combustion products that contribute to air pollution. Conventional drive link fixed angular values of duration and overlap, which leads to a compromise setting of these values, which is not optimal for inactive or high rpm.Attempts to address this problem are found in the prior art. For example, U.S. Pat. No. 1,622,491 (Coatalen et al) discloses a mechanism for varying the angular relationship of two axes with respect to a third axis. In particular, r and epicyclic gears form part of a drive linkage which can vary the phase of a wheel of the pump t with respect to a conductor 1. Figures. 3, 4 and 4A show a wheel linkage Epicentric s (two parts) and r, which can be adjusted to vary the angular relationship of any of the wheels or driver related ppyo 1. This approach may not affect duration, but not change the phase relationship. In U.S. Pat. No. 1,358,187 (Brewer), a synchronization mechanism is disclosed in which the operation of the exhaust valve in relation to the inlet valve is altered by a gear train that changes the circumferential position of the axis of the exhaust valve relative to the crankshaft.U.S. Patent. No. 3,888,217 (Hisserich) shows a drive belt of the camshaft of variable valve timing in which a clearance is taken in the timing belt by a pair of idler pulleys. Idler pulleys can be moved to change the angular relationship of the drive pulley on the crankshaft with respect to a driven pulley on the camshaft. Separate camshafts can be provided for the intake and the lobes of the exhaust valve, respectively, in which case the amount of overlap of the valve can be controlled.U.S. Patent. No. 3,502,059 (Davis et al) discloses an adjustable gear train in which connecting brackets 76 and 78 secure the center to center distance between the respective pairs of idle gears and the drive gears mad located between the crank shaft and a pair of camshafts. Each holder can be moved to adjust the lash between its associated idler gear and a driven gear mounted on a respective camshaft.In an article entitled "Eccentric Cam Drive Variable Valve Timing" (Automotive Engineering, vol. 88, No. 10, October 1980), a distribution system is disclosed based on a pinion eccentric offset with respect to a single overhead camshaft. The drive sprocket is mounted on a cross slide which moves against the force of a spring tensioned to decrease gradually with increasing eccentricity speed. The result is slow inlet openings the inlet valve before closing the valve, and delaying the opening of the exhaust valve. Finally, in an article entitled "Control Valve Timing Overlay Variable" by Stojek and Stwlorok, separate camshafts for the inlet valves and exhaust valves. A central helical gear driven by the crankshaft via a chain of rollers cooperates with two helical gear cam shafts for selectively angularly positioning gear shaft cam drive relative to the other. The gears are driven by toothed sleeves, which in turn are powered by electric motors controlled microprocessor, thus allowing variable valve overlap.While the above systems, in general, have demonstrated the possibility of selectively varying valve overlap, and to a limited extent, the duration of the valve, which do not adequately address the need to respond to changes in widths ranging rpm motor.Therefore, it is an object of the present invention is to provide, in an internal combustion engine, a link operable to couple a cam shaft with the crank shaft in a cyclic manner to accelerate and decelerate the camshaft in response to the rotation of the crankshaft on a constant speed.Another object is to provide means to counteract the increase in real time of valve overlap as the number of revolutions of an internal combustion engine decreases.Another object is to provide optimal intake and timing of the exhaust valve in a wider range of engine rpm in order to increase power and fuel economy and reduce engine emissions.In a broader sense, an object of the invention to provide a relatively simple means to selectively and cyclically accelerating and decelerating a driven shaft in response to rotation of a drive shaft at a constant speed.
SUMMARY OF THE INVENTION
To achieve these and other objects, there is provided an apparatus for effecting cyclic accelerations and decelerations in a driven shaft in response to rotation of a drive shaft at a constant speed. The apparatus includes a drive shaft and a means for rotating the drive shaft about a fixed longitudinal shaft, and a driving gear concentrically mounted on the drive shaft for rotation with the drive shaft. The apparatus further includes a driven shaft rotatable about a longitudinal axis of the driven shaft fixed relative to the drive shaft and a driven gear concentrically mounted on the driven shaft for rotation therewith. A drive linkage operable means engages the drive gear and the driven gear, and includes a first intermediate gear rotatable about a first longitudinal axis. A first connecting means is rotatably mounted to the drive sprocket and the first idler gear to maintain the drive gear and the first gear in driving engagement while maintaining a fixed distance between the gear shaft and the first drive shaft. A second intermediate gear is rotated about a second longitudinal axis, and a second connecting means is rotatably mounted to the first and second intermediate gears for maintaining these gears in driving engagement while maintaining a distance fixed between the axles. A third connecting means is rotatably mounted to the second gear and the driven gear, to keep the second gear and driven gear in driving engagement while maintaining a fixed distance between their respective axes.Finally, it provides a means of movement to move transversely controllably and one of the first and second intermediate gears during rotation of the drive gear. Such a transversely reciprocating first and second axes, thus dynamically alter the phase relationship between the drive gear and the driven gear.The movement means can include a cylindrical pin extending longitudinally mounted on the second intermediate gear in a position spaced apart transversely of the second axis at a first distance selection, along with means for controllably move transversely to the axis correspond to the second speed and second axis.A preferred form of drive means includes third and fourth intermediate gear. The third gear rotates about a longitudinal axis third and fourth gear rotates on fourth longitudinal axis. A fourth connecting means is rotatably mounted to the third gear and the drive gear for the maintenance of these gears engaged and operable to maintain a fixed distance between their centers. Likewise, a fifth connecting means maintains the third and fourth gears in driving engagement while maintaining a fixed transverse spacing between the third and fourth axes. The pin mounted on the second intermediate gear is also mounted to the fourth intermediate gear, thereby rotatably mounting the second and fourth intermediate gears with respect to each other.The pin is advantageously mounted to the fourth gear in the same manner as for the second gear, that is, a transverse distance from the axis of the gear selected. When transverse distances selected to the second and fourth gears are equal, a third selected motion of the intermediate gear can be positioned concentrically fourth gear to the second gear, in which case the rotation of the drive shaft at a constant speed spins the driven shaft at a constant speed. The movement of the third toothed wheel away from said intermediate position causes the alignment of the accelerations and decelerations in the driven shaft, as the shaft rotational speed of the disc remains constant.A specific application of this apparatus is operated in association camshaft of the internal combustion engine starting cycle four-axis. In particular, the third intermediate gear or "control" may be located in its position of alignment corresponding to maximum engine rpm selected operation. At this level, the camshaft running at a constant speed typically half that of the crankshaft angular velocity. With a decrease in engine rpm, the drive gear is moved in an arcuate path around the drive shaft, gradually away from the alignment position. Moreover, the intermediate gears are arranged such that the angular velocity segment highest fully accelerated or driven shaft (camshaft) of rotation coincides with the overlap condition of the valve. Consequently, the real time overlay need not constantly decreases with increasing engine RPM.result of this arrangement a relatively large overlap at high rpm is available to overcome the effects of inexhaust gases and the fuel / air charge, resulting in a higher yield. At the same time, a relatively small overlap at lower engine speed can reduce the engine idle speed is necessary to reduce the fuel consumption at lower speeds including idle speed, improved low-end torque and range average speed, and reduce undesirable engine emissions.In the drawingsFor a greater appreciation of the features and advantages, and others, are referred to the following detailed description and drawings, in which:. Figure 1 is a schematic illustration of a simple gear train involved in illustrating the present invention;Figures. 2 and 3 illustrate the gear train of Fig. 1 in different operating positions;. Figure 4 is a side elevation of the gear train of Fig. 1 detachable to reveal the separate pieces;. Figure 5 schematic view of a gear train constructed according to the present invention and used for engagement with a camshaft driving an internal combustion engine starting cycle four and shaft;Figures. 6 and 7 illustrate the gear train of Fig. 5 in different operating positions;. Figure 8 is a side elevation of the gear train of Fig. 5 removed to show separate parts;. Figure 9 is a schematic view showing two intermediate gears of the gear of FIG. 5, and. 10 is a graph illustrating the angular positions of a driven gear train unit corresponding to the selected angular positions of a drive gear of the gear train, the gear positions for alternative control.Detailed Description of the Preferred EmbodimentTurning now to the drawings, shown in Fig. January 1st drive train includes a drive gear 16, a first intermediate gear 18, a second intermediate gear 20, a first driven gear 22, and a second driven gear 24, rotating, respectively, about the central axes 26, 28 , 30, 32 and 34, all of which appear as dots in the figure and can be conveniently considered as the longitudinal axes. An elongated, substantially rigid first link or rod 36 is rotatably mounted at its opposite ends to the centers of gear transmission 16 and the intermediate gear 18, respectively, thus operable to maintain these gears engaged with one another while maintaining a fixed distance between the axes 26 and 28. A second rod or link 38 is similarly mounted to and maintained similarly intermediate gears 18 and 20 engaged operable. A third link rod 40 intermediate thereof is mounted and maintains the intermediate gear 20 and driven gear 22 drivable compromised. The gear shafts 16, driven gear 22 and driven gear 24 are fixed.Gears 16-24 are all the same size. Accordingly, rotation of the drive gear 16 at a selected angular velocity causes rotation of each of the other gears at the same speed, and in a direction for each gear, as indicated by the arrow associated.As illustrated in the figure. 1, drive gear 16 and the driven gear 24 are in phase. In particular, a position A along the perimeter of the drive gear 16 and a position B along the perimeter of the driven gear 24 are both at a position "three" and remain aligned with one another as the gears 16 and 24 rotate in concert.A fourth link 42 and the fifth link 44 are rotatably mounted to the center of the gear unit 16 and the intermediate gear 20, respectively, and are pivotally attached at their opposite ends in a junction control 46. The phase condition in the driven gear unit and is maintained as long as the control output 46 is located as shown in Fig. 1.Control linkage 46 to move to the position illustrated in Fig. 2 close the parallelogram formed by links 36, 38, 42 and 44, to increase the distance between the drive gear 16 and intermediate gear 20, so the driven gear 24 to rotate counterclockwise relative to the rotation of the gear drive 16. As indicated by the relative locations of positions A and B, the driven gear 24 is no longer in the same phase relation with the driving gear, after being delayed or rotated counterclockwise relative to the drive sprocket .Conversely, movement of the control linkage 46 in the opposite direction widens the parallelogram formed by rods 36, 38, 42 and 44 to reduce the distance between the drive gear 16 and intermediate gear 20. This rotating driven gear 24, ie the gear clockwise, in relation to the rotation of the drive gear 16. Driven gear 24 is further provided with the driven gear 22 in order to more clearly illustrate the changes in the phase relationship such as gear 24, as drive gear 16 rotates clockwise. Gear 22 course experience similar changes.It is appreciated that the phase relationship of the driving and driven gears ca achieved through direct movement of either idler intermediate gear 18 or 20 as well as through direct binding motion control 46. Moreover, the gears do not need to be the same size, in the event that gear 24 can rotate in a multiple or fraction of the speed of the drive gear. In either case, the phase relationship is controlled by controlling the distance between axes 26 and 30 of the gears 16 and 20, respectively. . Figure 4 illustrates the gears and their respective shafts and a shaft 48 connecting the control 46.As driven gear 24 is advanced in relation to the drive gear 16, the speed (and driven gear 22) is momentarily greater than the speed of the drive gear. By contrast, the driven gears travel a relatively slower angular velocity as the position B is moved in the leftward direction with respect to the position A. Consequently, periodic increases and decreases cyclically in separation or the axes 26 and 30 result in corresponding cyclical acceleration and deceleration of the driven gear 24 in response to rotation of drive gear 16 at a constant speed.Figures. 5-8 illustrate a gear train arranged to provide a selected oscillation of an intermediate gear with respect to a drive gear in relation to the operation of an internal combustion engine of four strokes. Most motor structure not shown as known and not considered particularly pertinent to the present invention.Returning to FIG. 5, a drive gear 52 is concentrically mounted on a crank shaft 54 to rotate clockwise with the same around a drive shaft 56. A first intermediate gear 58, a second intermediate gear 60 and a driven gear 62, together with a cam gear shaft 64 form a drive train which engages with a cam shaft 66 and the crank shaft. Cam gear shaft 64 is concentrically mounted on the camshaft for rotation therewith about an axis of the camshaft 68. The axis of the camshaft, an axis of the driven gear 70 driven 62 and the drive shaft 56 are fixed in relation to every block of the internal combustion engine. Gear 64, as previously described gears 24, however, is not essential (gear 62 would suffice) useful for visualizing the phase relationship with the drive gear 52.A first elongated link or rod 72 is rotatably mounted at its opposite ends to the centers of transmission gears 52 and the intermediate gear 58, respectively, thereby to maintain these gears in a driving engagement and fix the distance between the drive shaft 56 and a shaft 74 intermediate gear 58. Similarly, a second elongated link 76 is mounted to the intermediate gears 58 and 60, and a third elongated link 78 is mounted similarly to the gears 60 and 62. Therefore, the shafts 74 of the gears 58 and 80 of gear 60 are not fixed relative to the engine to permit controlled variation of the distance between the shaft 60 and the drive shaft 56.A second gear train associated with the drive gear 52 includes a gear 82 and a control oscillator gear 84 (Figure 8) and axially aligned behind the gear 60 as shown in Fig. May. A first control link 8 is rotatably mounted at its opposite ends to the centers of gear 52 and transmission gear control 82, respectively, to maintain these gears in driving engagement, and set the distance between their respective centers. Similarly, a second control link 86 is pivotally mounted to control the gear 82 and the gear 84 to maintain these gears similarly. As seen in the figures. 6, 7 and 8, the control gear 82 is not operable engaged with any of the intermediate gears 58 and 60.Control gear 82, due to the control link 84, not only rotated but can be moved in an arcuate path about the drive gear 52, thereby to controllably alter the shape of the parallelogram formed by links 72, 76, 85 and 86 and thereby control the linear distance between the drive shaft 56 and idler shaft 80 60. For this purpose, schematically shows a piston 88 at one end of a rod 90, the other end of which is rotatably mounted for controlling the gear 82 at its center. Piston 88 is reciprocable within a cylinder 92 and a rod 94 fixed to the cylinder is pivotally connected to the engine block or other point integral with the engine block as indicated at 96.Therefore, extension and retraction of the piston 88 within cylinder 92, by means well known and therefore not shown, moving the control equipment 82 along its arcuate path. It should be recognized that alternative means may be employed for controllably positioning gear 82, for example, a cam follower and the cam arrangement of the worm gear, rack and pinion, or the like. For an example of one approach, reference is made to U.S. Patent No. 3,888,217 (Hisserich).As seen in Fig. 8, drive gear 52 has an axial dimension considerably more than double that of the remaining gears in order to permit longitudinal or axial separation of the gear train formed by gears 52, 58, 60 and 62 and the gear train control including gears 82 and 84. Accordingly, the piston 88 and rod 90 can be extended as shown in Fig. 6, in which control device 82 passes behind intermediate gear 58 as seen in the figure, thereby to increase the separation between the drive shaft 56 and the shaft 80. Alternatively, the piston and cylinder can be retracted to shorten the distance between these axes, as shown in Fig. July. It should be recognized that while the rod 90 is connected to control gear 82, the link could thus be operated via a direct connection to one of the other gears, for example intermediate gear 58.Returning to FIG. 8, a longitudinally directed elongated cylindrical pin 98 is connected to the intermediate gear 60 and gear 84 in a manner to allow rotation of these gears with respect to another. For example, the pin 98 is rotatably mounted to both of these gears, although alternatively the pin may be fixed to one of the gears and rotatably mounted to the other. As seen in Fig. 9, the pin 98 is mounted on each of the gears 60 and 84 in a transversely offset from the center of each gear, and by the same amount. The transverse displacement of the pin 98 is illustrated by 80 and 100 axes of the gears 60 and 84, respectively, in Fig. 9.Because the lateral displacement is the same in both instances, the gear 84, through the apparatus control unit 82 can move in axial alignment or concentric with the gear 60 as shown in Fig. May. In this axially aligned position, the phase relationship of the driving gear 52 and camshaft gear 64 is constant, and hence the driven gear undergoes no acceleration or deceleration, as long as the speed of the drive gear remains constant.Moving control unit 82 to change the gear position 84 creates a cyclical movement of the intermediate gear 60, which can be divided into three main components: (1) the rotation of the intermediate gear 60 on shaft 80, (2) Revolution intermediate gear 60 about the pin 98 in a circular path having a radius equal to the transverse offset, and (3) the travel of pin 98 in a circular path due to the rotation of the gear 84 in a circular path with a radius equal to transverse displacement. Accordingly, since a displacement of a quarter of an inch, for example, transversal positioning gear 82 for aligning shafts 80 and 100 on opposite sides of the pin 98 is obtained by a shift of one-half inch maximum.The maximum displacement, and to a lesser extent in any configuration the gears 60 and 84 are not concentric, resulting in a cyclic or oscillatory movement of intermediate gear 60, generally as described above. However, the exact path of travel to intermediate gear 60 is also determined by link 78, thereby limiting travel intermediate gear 60 to an arcuate path about the center of driven gear 62. Generally, during a portion of each cycle race idler gear 60 relative to the gear 62 is additive to an increase in rotation speed of driven gear 62. During another part of the cycle, the travel of the gear 60 relative to the gear 62 is in the opposite direction, resulting in the decrease in rotation speed of driven gear. Consequently, the driven gear 62 undergoes periodic acceleration and deceleration in response to rotation of the drive gear at a steady speed.Preferably piston 90 and cylinder 92 are operated to selectively position control unit 82 based on the engine speed (rpm), and further adjusted so that control unit 82 positions oscillator gear 84 in the aligned position relative to the intermediate gear 60 (FIG. 5) when the engine rpm is at a selected maximum value. Furthermore, the rotation of the cam gear shaft 64 is in a selected phase relationship with the gear 52, so that for a non-concentric positioning of the gears 60 and 84, the portion of the accelerated speed up gear camshaft and driven gear rotation coincides with the valve overlap, that is, the time during which the cam lobes of the camshaft is polarization both the intake valve and the exhaust valve in the open condition. Finally, the piston and cylinder are operated to increase the displacement of the gears 60 and 84 as the motor speed decreases to a shift speed matches the maximum idling.We must recognize that the embodiment of FIGS. 5-9 is described as a simplified version in which all the gears have the same diameter. It is considered within the skill of the art to modify the embodiment, for example, to provide for the usual rotation of the camshaft 66 at half the speed of the crankshaft 54, and further to provide multiple phase shifts , or accelerations and decelerations alternately, in a single rotation of the crankshaft 54, or to provide separate drive trains time separate exhaust camshaft and the intake, or even multiple cylinders, all based on a single axis of crank.
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