JP2004084952A - Gear assembly, gear train assembly and its assembling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlash preventive gear assembly since it is particularly important to reduce noise when the noise on the basis of backlash of a gear train is large particularly in a diesel engine. <P>SOLUTION: An engine device having the gear train for imparting the timing of the engine is disclosed. A technology for minimizing the backlash and the noise of the gear train is indicated. The backlash preventive gear assembly for minimizing the backlash of the gear train is also indicated. One disclosed backlash preventive gear assembly includes at least two gears, and the circular arc tooth thickness of a tooth of one gear is set smaller than the circular arc tooth thickness of a tooth of the other gear. A gear assembly having a biassed torque of at least about 135 N-m (100ft-1bs) is also disclosed as a separate backlash preventive gear assembly. A device for almost matching a tooth of the assembly to be installed by being carried on the backlash preventive gear assembly is also disclosed. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to gears, and more particularly, but not exclusively, to reducing gear train backlash.

Conventional technology

When a tooth of one gear meshes with a gap of another gear, the gap typically has a space larger than the space required to accommodate the teeth. This excess space is sometimes referred to as rush or backlash. Backlash varies with a number of factors, including radial play in gear bearings, eccentricity of gear shafts, inaccuracy in clearance between gear centers and gear-to-gear variations typical of many gear manufacturing processes. Varies with many factors, including

Extra gaps associated with backlash usually cause excessive impact loads on gear teeth. This load can cause excessive noise or other gear train problems. For example, backlash promotes gear wear. Reducing backlash is particularly important in internal combustion engines, especially in gear trains of diesel engines. U.S. Pat. Nos. 5,450,112, 4,920,828, 4,770,582, and 3,352,003 provide background information on the application of gear trains to various engines.

One way to reduce backlash is through precision machining and mounting of gears. However, this method is usually expensive and does not adequately handle backlash that changes over time due to wear. Another way to reduce backlash is to insert one or more scissor gears between gear trains. Usually, the teeth of the scissor gear are adjustable so as to occupy the space between the teeth of the meshing gear. U.S. Pat. Nos. 4,747,321, 4,793,670, 3,365,973, and 2,607,238 show examples of various types of scissor gears.

バ ッ Backlash control by scissor gears is limited when the scissor gears mesh with two or more gears having different amounts of backlash. Typically, the effective tooth size of a scissor gear is determined by the gear with the least backlash, which is usually inappropriate when the other meshing gear has a large backlash. One solution to this problem is to select gears that mesh to minimize backlash differences, but this backlash adaptation method is usually time consuming and expensive. Therefore, in the case of a gear train, there is a need to deal with backlash differences in a number of gears that mesh with the scissor gear.

One form of scissor gear is one in which two gears rotatable about a common center are spring-biased from each other. In this configuration, the gear teeth of each pair of gears expand and fill the gap between the teeth of the gears that mesh. In some gear trains, the load imposed on the tooth pairs by the meshing gears is large enough to align each gear pair against the biasing force of the spring. Typically, each gear of a matched gear pair has the same nominal tooth thickness and a shape that proportionally shares a high load. However, a random deviation from the nominal value usually causes one or the other tooth of each pair to deform under abnormally high loads to conform to the other gear. During this deformation process, the gear teeth are often subjected to reverse loads and wear out more rapidly than when subjected to unidirectional bending loads. Such deformation also causes large changes between the teeth, degrading performance and increasing gear train noise. Accordingly, there is a need for a backlash-free gear assembly that does not suffer from these disadvantages and allows for high loads.

ノ In the case of heavy-load diesel engines, knocking occurs in the combustion stroke, but it may be caused by gear tooth noise due to high impact. Typically, this noise cannot be sufficiently eliminated by ordinary scissor gears. Therefore, an improvement in the gear train is required for this type of noise.

The present invention relates to a backlash-free gear assembly and gear train using one or more backlash-free gear assemblies. Various aspects of the invention are novel, non-obvious, and have various advantages. While the essence of the invention is to be determined solely by the appended claims, certain features which characterize preferred embodiments are outlined below.

In one form of the invention, a gear train is assembled by defining a first gear and establishing a first mesh between the first gear and the second gear. The second gear is of the scissor gear type and the effective value of the tooth size is determined by the first mesh. The mounting position of the third gear is selected to form a second mesh with the second gear. This mounting position is determined as a function of the effective tooth size and controls the backlash of the second mesh.

In another aspect, an engine device including a gear train is provided. The apparatus includes an internal combustion engine to which first, second and third gears are pivotally connected. The second gear engages the first gear by a first mesh, and the third gear engages the second gear by a second mesh. The second gear is of the scissor gear type. The device includes an adjustable positioning mechanism, adapted to provide a range of positions of the rotation axis of the third gear relative to the rotation axis of the second gear to control the backlash of the second mesh. Includes a possible positioning mechanism. One advantage of this form of the invention is that a difference in backlash between the two gears meshing with the scissor gear is indicated.

In another aspect of the invention, an anti-backlash gear assembly is provided, wherein a first gear having a first number of circumferentially arranged teeth, and a first gear under spring bias. An engaging second gear, wherein the spring biasing force causes the first gear and the second gear to rotate relative to each other about a substantially common center of rotation. The second gear includes a number of circumferentially arranged teeth, each paired with a corresponding tooth of the first gear. Each tooth pair has a compound tooth thickness determined by the force acting against the biasing force. The first teeth each have a first arc thickness and the second teeth each have a second arc thickness, which is nominally less than the first thickness. Generally, this difference in tooth thickness reduces the reverse bending load by utilizing a load that exceeds the biasing force on the first gear.

In yet another aspect of the present invention, an anti-backlash gear assembly, such as a scissor gear, is provided with a high maximum bias torque to reduce knocking noise of a diesel engine. Typically, the maximum bias torque required to reduce these noises is selected as a function of the particular engine design and expected load. In a preferred embodiment, the maximum bias torque is at least about 100 ft-lbs (135 Nm). In a more preferred embodiment, the maximum bias torque is at least about 270 N-m (about 200 ft-lbs). In a more preferred embodiment, the maximum biasing torque is at least about 500 ft-lbs. Contrary to conventional wisdom, this relatively high biasing torque has been found to be effective in reducing the unpleasant hammering and knocking sounds often found in diesel engines.

In yet another form, the anti-backlash gear assembly includes a first gear having a first number of circumferentially arranged teeth and a first number of splines. The assembly further includes a second gear having a second number of circumferentially arranged teeth and a second number of splines. The first and second splines engage one another about a substantially common axis of rotation and are inclined relative to this axis to cause the first and second gears to rotate relatively. The first and second teeth change size with the relative rotation of the first and second gears in pairs.

In another form of the invention, an anti-backlash gear assembly engages a first gear having teeth disposed in a first number of circumferential ways and a first gear under spring bias. A second gear that rotates relatively about a common axis of rotation. The second gear includes a second number of teeth, each tooth being paired with a corresponding tooth of the first gear to form multiple variable tooth thickness compound teeth to reduce backlash. An alignment device is provided having a threaded stem carried on the first gear and a head. The head is selectively positioned on the first gear to provide an adjustable support relationship for the second gear to oppose a biasing force that causes a corresponding change in the alignment of the first and second teeth. Desirably, the head has one location that substantially aligns the first and second teeth to facilitate mounting the assembly to a gear train.

In another aspect of the invention, the anti-backlash gear assembly is incorporated into a gear train for use with an internal combustion engine.

Action

According to the present invention, the backlash of a gear train assembly having a scissor gear is reduced by arranging a combination gear that meshes with a scissor gear having an effective tooth size determined by another mesh.

According to the present invention, noise generated by the gear train of the engine is reduced.
According to the present invention, there is provided an anti-backlash gear assembly in which the generation of gear train noise is reduced.

According to the present invention, an anti-backlash gear assembly with reduced noise generation by applying a relatively high bias torque is obtained.
ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to control the load division between several gears of a scissor gear assembly.

Further, according to the present invention, an anti-backlash gear assembly that is easy to install and has high reliability is obtained.
Other objects, features, effects, and aspects of the present invention will become apparent from the following description with reference to the drawings.

た め To facilitate understanding of the present invention, embodiments are shown in the accompanying drawings, and specific terms are used to describe the embodiments. However, they do not limit the invention. That is, the scope of the present invention is not limited. Variations and modifications of the described apparatus and applications of the principles of the invention described below that can be readily made by those skilled in the art are within the scope of the invention.

FIG. 1 shows an internal combustion engine device 20 according to the present invention. Apparatus 20 includes an engine block 22 having a crankshaft 24 shown in dashed lines. Further, the device 20 includes a head assembly 30 connected to the engine block 22. The head assembly 30 includes a fuel injection camshaft 32 shown by a broken line and a valve camshaft 34 shown by a broken line. In one embodiment, block 22 and head assembly 30 are high capacity in-line 6 cylinder diesel engines. The invention is applicable to other types of institutions known to those skilled in the art.

The device 20 includes a timing gear train 40. The gear train 40 includes a drive gear 42 connected to the crankshaft 24. The crankshaft 24 and the drive gear 42 have a center of rotation 44 indicated by a crosshair. In the drawings, the center of rotation is shown as a chain line or a broken line when the rotation axis is not perpendicular to the drawing, and is shown as a cross line when it is perpendicular to the drawing. The gear 42 rotates with the crankshaft 24 about the center 44 during operation of the engine device 20 to drive the remaining gears of the gear train 40.

The gear 42 has teeth 46 which mesh with a lower anti-backlash idle gear 50. The gear 50 rotates around an axis 53 having a center of rotation 54. Shaft 53 is attached to block 22 by fasteners or fasteners 55. A bearing 56 provides rotational support between the shaft 53 and the anti-backlash gear assembly 58 of the gear 50.

FIGS. 2-5 show additional details regarding the construction and operation of the anti-backlash gear assembly 58 of the gear 50. FIG. FIG. 2 shows details of the gear 60 before being assembled into the gear assembly 58. The gear 60 includes a hub 63. A web 64 defines seven circumferentially spaced openings 65. In addition, for each opening 65, the web 64 has a finger edge 65a at one end and an edge 65b opposite the other end. The opening 65 and the edges 65a, 65b are substantially evenly spaced along the circumference of the imaginary circle around the center 54. The gear 60 has a number of circumferentially spaced gear teeth 66 limited to a rim 67. The rim 67 is connected to the hub 63 by a web 64. Adjacent members of the gear teeth 66 are substantially equally spaced from each other by a gap 68. The teeth 66 and gaps 68 are only given a few numbers for clarity. The members of the gear teeth 66 have substantially the same size and shape. Similarly, the gaps 68 have substantially the same size and shape.

Referring to FIG. 3, gear 70 of anti-backlash gear assembly 58 is shown. The gear 70 includes a hub 73, and the hub 73 is in a rotationally supporting relationship with the shaft 53 via the bearing 56 (see FIG. 1). The hub 63 of the gear 60 is engaged with the hub 73. The interference between hub 63 and hub 73 allows for relative rotation of gears 60,70. The gear 70 includes a web 74. A tab 74a projects from the web 74 in a direction substantially perpendicular to the plane of FIG. 3 and is connected on one side to the rim 77 to define a corresponding recess 75. At least one tab 74a defines a threaded hole 79 therethrough. The threaded hole 79 has a longitudinal axis substantially parallel to the plane of FIG. The webs 74 each define a weight reduction hole 75a corresponding to each of the recesses 75. Recess 75 and tab 74a are substantially evenly spaced along the circumference of an imaginary circle about center 54.

Gear 70 includes a number of gear teeth 76 defined by a rim 77. The rim 77 is integrally attached to the hub 73 by a web 74. Adjacent members of the gear teeth 76 are spaced with a substantially equal gap 78 from each other. Only a few teeth 76 and gaps 78 are shown. The gear teeth 76 have substantially the same size and shape. Similarly, the gap 78 has substantially the same shape and dimensions. Preferably, the number of teeth 76 of gear 70 is the same as the number of teeth 66 of gear 60.

FIG. 4 shows the anti-backlash gear assembly 58 in a misaligned state normally seen prior to installation in the gear train 40. The gears 60, 70 loosely engage each other, and each opening 65 of the gear 60 substantially overlaps a corresponding recess 75 of the gear 70 to define a plurality of pockets 80. A number of coil springs 81 each having one end 82 and the other end 84 are provided. Each spring 81 is respectively positioned in a corresponding pocket 80, ends 82 engage corresponding tabs 74a, and ends 84 align with corresponding edges 65a. However, end 84 need not engage edge 65a.

Assembly 58 further includes an adjustment bolt 90 having a threaded stem 92 and an opposing head 94. The stem 92 is threaded sufficiently to be screwed into the hole 79 in FIG. 4, and the head 94 contacts the corresponding tab 74a. Typically, the teeth 66, 76 are in an unaligned position, the teeth 66 overlap a gap 78 defined between the teeth 76, and the teeth 76 overlap a gap 68 defined between the teeth 66. The hub 73 of the gear 70 forms a rotational support relationship with the hub 63 of the gear 60, and the gears 60 and 70 are relatively rotatable. The head 94 defines a contact surface 95 shaped to support the adjacent edge 65b of the gear 60 as the gear 60 rotates counterclockwise relative to the gear 70. As the gear 60 rotates clockwise relative to the gear 70, the spring ends 84 engage the corresponding edges 65a. Desirably, each edge 65a defines a finger sized to fit within the coil of each spring 81 to facilitate proper alignment with gear 60. When rotated clockwise with sufficient force, the spring 81 is compressed between the corresponding edge 65a and the tab 74a, as shown in FIG.

FIG. 5 shows the aligned positions of the gears 60 and 70, and shows a state suitable for attachment to the gear train 40. In alignment, the teeth 76, 66 overlap each other as shown in FIG. The spring 81 is in high compression between the edge 65a and the tab 74a, producing a correspondingly high spring force. The adjustment assembly 58 is changed from the configuration of FIG. 4 to the configuration of FIG. 5 by loosening the bolt 90 and the head 94 moves away from the hole 79 along the axis S of the stem. As this loosening movement continues, the surface 95 is supported on the adjacent edge 65b and the spring 81 is compressed between the adjacent matching tab 74a and the edge 65a.

Loosening the bolt 90 separates the associated tab 74a and edge 65b, causing the gears 60, 70 to rotate relative to one another and the teeth 66, 76 to move relatively. The gear teeth 66 pass through a number of teeth 76 between the non-biasing position of FIG. 4 and the high-biasing position of FIG.

FIG. 5 shows the surface 66 a of the tooth 66 of the gear 60. The teeth 76 of the gear 70 also have a surface 76a, some of which are illustrated. The tooth width of a representative surface 66a is shown as W60. Similarly, the tooth width W70 indicates the tooth width of the representative surface 76a. Desirably, the tooth width W60 is smaller than the tooth width W70. More preferably, the tooth width W70 is at least about 50% larger than the tooth width W60. More preferably, the tooth width W70 is at least about twice the tooth width W60.

4 and 5, anti-backlash gear assembly 58 is constructed by providing gear 70 and aligning one of springs 81 with bore 79. Bolts 90 are threaded into holes 79 to bring head 94 into contact with associated tab 74a. The remaining spring 81 is located in the recess 75 of the gear 70. A gear 60 is located on the gear 70 to define a corresponding pocket 80 substantially equally spaced along an imaginary circle 86 (shown in broken lines in FIG. 4). The edge 65a is aligned with the corresponding end 84 of the spring 81.

Prior to mounting assembly 58 on shaft 53, it is desirable to align teeth 66,76. To provide this alignment, bolt 90 is partially loosened from hole 79 so that head 94 contacts adjacent edge 65b of gear 60 and correspondingly compresses spring 81. In response, the teeth 66, 76 move past each other. By loosening the bolt 90, this movement will continue to substantially reach the alignment position shown in FIG. As a result, the gear 60 separates from the gear 70 along the axis S by a distance D as shown in FIG. Note that the stem 92 of the bolt 90 is partially threaded into the hole 79 in both the unaligned position of FIG. 4 and the aligned position of FIG. In another embodiment, one or all tabs 74 a align holes 79 with bolts 90. Similarly, if there are multiple holes 79, multiple bolts 90 may be used.

When the teeth 66 and 76 are aligned in the configuration of FIG. 5, the assembly 58 is mounted on the shaft 53 via the bearing 56. Upon completion of the installation, the aligned teeth 66, 76 form a mesh 48 with the teeth 46 of the drive gear 42. However, the mesh 48 has a significant amount of backlash if the teeth 66, 76 are forced to align by an extension of the bolt 90. In order to eliminate the backlash of the gear 50, the gear 60 and the gear 70 are relatively rotatable under the biasing force of the compressed spring 81. After the assembly 58 is mounted, the bolt 90 is screwed into the hole 79 to form the meshing 48 with the drive gear 42, so that it is rotatable. As a result, the biasing force of the spring causes the teeth 66,76 to deflect against each other and occupy the entire space between adjacent teeth 46 forming the meshing 48. Of particular note, the mesh 48 does not allow the teeth 66, 76 to return to the unloaded position shown in FIG.

Each pair of initially aligned teeth 66, 76 acts as a composite tooth having an overall variable effective dimension, i.e., tooth thickness, the "teeth thickness" varying with the dimensions between the combined teeth 46. When the "teeth thickness" is changed, the backlash of the meshing 48 is reduced by the compound teeth or substantially zero. To complete the assembly 58, bolts 90 are tightened so that the head 94 contacts the associated tab 74a. Bolts 90 are preferably carried on gear 70 during the adjustment process, and assembly 58 is utilized as part of gear 50.

Preferably, the gears 60, 70 are machined from a metal material suitable for long term use as a timing train for a diesel engine. Bolts 90 and springs 81 are also preferably made of materials suitable for long term use for diesel engines. However, other materials known to those skilled in the art may be used.

The gear 50 is shown in FIG. 1 as an idle gear, but may be a drive gear, a driven gear, or another arrangement known to those skilled in the art. In all cases, gear 50 is a new type of scissor gear.

Referring to FIG. 1, the gear 50 forms an engagement 96 with the idle gear 100 in the gear train 40. Idle gear 100 rotates about a center of rotation 104 to define circumferential teeth 106 spaced by a gap 108 to form gear 96 with gear 50.

Referring additionally to FIG. 6, details of the idle gear 100 are shown. Idle gear 100 includes a rim 107 integrally connected to web 114 to define teeth 106. The web 114 has a weight reduction hole 116. The web 114 is integrally connected to a hub 118, which has a somewhat smaller tooth thickness along the axis of rotation corresponding to the center 104 as shown in the cross-sectional view of FIG. A cylindrical bush 119 provides a rotating bearing surface between the shaft 103 and the hub 118. Shaft 103 defines four passages 105 for attaching idle gear 100 to block 22.

The idle gear 100 is mounted by an adjustable positioning mechanism 120. The mechanism 120 includes a mounting plate 130, which is located between the shaft 103 of the idle gear 100 and the block 22. It should be noted that the plate 130 has a gap between the hub 118 of the idle gear 100 and the idle gear 100 is free to rotate about the axis 103.

The idle gear 100 and the mounting plate 130 are located between the block 22 and the holding plate 140. The holding plate 140 has mounting holes 145 substantially aligned with the mounting holes 105 of the shaft 103, the mounting holes 135 of the plate 130, and the screw holes 25 of the block 22. Note that hole 105 has a larger dimension with respect to an axis perpendicular to the axis of rotation of gear 100 than mounting hole 135, mounting hole 145, and screw hole 25. Idle gear 100 inserts a cap screw fastener 150 through plate 145, passage 105 and passage 135 between plate 130 and plate 140 and thread the end of threaded stem 152 into hole 25. Fixed by The fasteners 150 each have a head 154 that opposes the threaded stem 152. When the stem 152 is sufficiently screwed into the hole 25, the head 154 contacts the holding plate 140 and holds the holding plate 140 on the shaft 153, and holds the shaft 153 on the plate 130.

In operation, the mechanism 120 places the idle gear 100 in a planar area preferably parallel to the plane of FIG. 1 and perpendicular to the plane of FIG. In this area, the gear 100 has two degrees of freedom as indicated by arrows X and Y in FIG.

To mount the idle gear 100, the mounting plate 130 is first secured to the block 22 in a conventional manner using a fastener (not shown) and the passage 135 is aligned with the hole 25. When the plate 130 is fixed to the block 22, the idle gear 100 is positioned on the plate 130, and the passage 105 and the passage 135 overlap. Next, the holding plate 140 is disposed on the shaft 103, and the holes 145 overlap the corresponding passages 105, 135 and holes 25. Fasteners 150 are loosely screwed into corresponding holes 25 through respective matching holes 145, passages 105 and 135. Desirably, fixture 150 is first threaded into bore 25 by an amount sufficient to contact plate 140 and to hold idle gear 100 in a driven position. In this embodiment, the position of the idle gear 100 relative to the plane area indicated by arrows X and Y is selected within a range allowed by the play of the fixture 150 in the passage 105. When the XY position is selected, the fixture 150 is tightened and the idle gear 100 and the mechanism 120 are fixed.

歯 The teeth 106 of the idle gear 100 mesh with the backlash prevention gear 200 to form a mesh 196. The gear 200 is mounted on the fuel injection camshaft 32 of the cylinder head assembly 30 and rotates around a rotation center 204. Gear 200 desirably has a compound gear tooth pair, indicated by reference numeral 266, similar to gear 50. Further, the spring 281 of the gear 200 has the same shape as the spring 81 of the gear 50, but the number is small (three are shown). Similarly, a mounting adjustment bolt 290 is shown. This adjusting bolt has the same mounting function as the bolt 90 of the gear 50. A belleville washer may be used on one or both of gear 50 and gear 200 to provide a spring biasing force with or without a coil spring.

The gear 200 forms a mesh 296 with the gear 300. The gear 300 is mounted on the valve camshaft 34 and rotates around a rotation center 304. The gear 300 defines a tooth 306 that interferes with the tooth pair 266 of the gear 200 to form a mesh 296.

時 に During operation, the drive gear 42 rotates together with the crankshaft 24 to rotate the gear 50. In response, gear 50 causes idle gear 100 to rotate through meshing 96. The idle gear 100 rotates the gear 200 via the mesh 196 to adjust the timing of a fuel injector (not shown) for the engine device 20 by rotating the fuel injection camshaft 32. In addition, gear 200 rotates gear 300 via meshing 296 and rotates valve camshaft 34 to provide timing for the engine valves (not shown) for head assembly 30. That is, the gear train 40 controls the timing of the engine device 20 by rotating the camshafts 32 and 34 of the head assembly 30 in response to the rotation of the crankshaft 24.

As another example, it is easy for those skilled in the art to use different numbers and arrangements of gears in the gear train 40. In yet another embodiment, a conventional scissor gear is used instead of gear 50 or gear 200 or both. In yet another embodiment, the idle gear having an adjustable positioning mechanism may be omitted.

In one embodiment of the gear train 40, the number of teeth 46 of the drive gear 42 is about 48, the number of teeth 66, 76 of the gears 60, 70 is about 70 each, and the number of teeth 106 of the adjustable idle gear 100 is The number is about 64, the number of compound teeth 266 of gear 200 is about 76, and the number of teeth 306 of gear 300 is about 76. Further, in this case, the gears 42, 50, 100, 200, 300 are spur gears, made of a metal material that can be used for a long period of time together with the internal combustion engine, and have a substantially parallel rotation axis substantially orthogonal to the plane of FIG.

構造 The structure and operation of the device 20 have been described above. The assembly of the device 20 will be described with reference to FIGS. 7A and 7B. 7A and 7B, the reference numerals are similar to those shown in FIGS. 1 to 6, but the meshing of the teeth is shown in an enlarged view, highlighting selected features of the invention. FIG. 7A shows an intermediate assembly stage of the drive gear train 40. At this stage, the drive gear 42 is already mounted and rotates about the center 44 in the direction indicated by arrow R1. Similarly, meshing gear 300 is mounted to rotate about center 304 in the direction indicated by arrow R5.

歯 車 After the gears 42, 300 are mounted, the gears 50, 200 are mounted so as to form a mesh 48 between the gears 42, 50 and a mesh 296 between the gears 200, 300. The formation of the meshes 48, 296 determines the effective composite size of the corresponding tooth pair when the teeth of the gears 50, 200 occupy the gaps between the teeth 46, 306 of the gears 42, 300, respectively. For gear 50, teeth 76 of gear 70 are shown in dashed lines and teeth 66 of gear 60 are shown in solid lines for clarity. The effective arc tooth thickness T50 of one compound tooth pair of the gear 50 is also shown. The effective arc tooth thickness is determined along the pitch circle of the gear 50 for the meshing. Note that in the absence of the idle gear 100, the tooth thickness T50 is determined by the mesh gap of the teeth 46 of the gear 42.

In mesh 296, gear 200 forms compound tooth pair 266. Each pair 266 has a member indicated by a broken line and a member indicated by a solid line for clarity. The effective arc thickness of one compound tooth pair 266 is shown as the arc thickness T200 relative to the pitch circle of the gear 200.

Arrows R4 and R5 indicate the directions of rotation when the gears 200 and 300 are driven, respectively. The mounting hole 25 of the engine block 22 is also shown for reference.
The compound arc tooth thickness T50, T200 is limited, and idle gear 100 is mounted to form a mesh 96 with gear 50 and a mesh 196 with gear 200 as shown in FIG. 7B. The tooth thickness T50, T200 of the tooth has a difference corresponding to the difference in the amount of backlash in the meshing 48,296. The mechanism 120 is used to adjust the XY position of the center of rotation 104 relative to the fixed centers of rotation 54, 204 so that the idle gear 100 optimally meshes with the predetermined tooth size of the gears 50, 200. However, this is not related to the backlash difference. The fasteners 150 of the mechanism 120 are shown in FIG. 7B for reference.

Adjusting the position of the idle gear 100 relative to the other gears is important in controlling the amount of backlash in the meshes 96,196. If the difference in backlash due to different tooth thicknesses T50 and T200 is within a certain range, the backlash is reduced by arranging the idle gear 100 at an appropriate position along a plane area perpendicular to the rotation axis of the meshing gear. Can be simulated or zero.

It should be noted that while two meshes 96, 196 are shown between the idle gear 100 in the preferred embodiment, backlash control when the number of meshed gears is different is also possible. For example, this technique can be applied to a gear train including three gears 42, 50, and 100.

Referring to FIGS. 8A-8C, selected operating states of gears 42, 50, 100 are schematically illustrated using the same reference numerals as in FIGS. 1-6, but with various features. Teeth are large and small in number for clarity. In FIG. 8A, gears 42, 50, 100 are in a stationary (non-moving) position with respect to each other. At meshing 48, virtual pitch circles C1, C2, C3 are indicated by dashed lines for gears 42, 50, 100, respectively. The arc tooth thickness T50a of the pair of gear teeth 76, 66 of the gear 50 is shown as an arc along the pitch circle C2. An arrow DF1 indicates a force acting against the biasing force of the gear 50 in the static state shown in FIG. 8A. The static reaction force of gear 100 is shown as arrow RF1. The arc tooth thickness T60 of the selected tooth 66 is also shown. The arc tooth thickness T70 of the selected tooth 76 is also shown. For each tooth 60, 70, the arc tooth thickness T60 is desirably nominally smaller than the arc tooth thickness T70. In one preferred embodiment, T60 is at least about 0.002 inches smaller than T70. More desirably, the difference is at least about 0.004 inches. Most desirably, this difference is in the range of 0.002-0.006 inches.

ＢIn FIG. 8B, the drive gear 42 rotates in the direction of the arrow R1, and gives the resultant driving force indicated by the arrow DF2. In response, gear 50 rotates in the direction indicated by arrow R2, and gear 100 rotates in the direction indicated by arrow R3. The reaction force shown on gear 100 is shown as arrow RF2. The resultant forces DF2, RF2 are large enough to partially overcome the spring bias and compress the spring 81 of the gear 50. As a result, the arc tooth thickness T50b of the composite pair of teeth of the gear 50 decreases as compared with the tooth thickness T50a (where T50b is smaller than T50a). As the magnitude of the force transmitted from drive gear 42 increases, gear teeth 66, 76 approach alignment.

8C, the resultant driving force DF3 of the gear 42 and the reaction force RF3 of the gear 100 compress the spring 81 to align the gear teeth 66 and 76. When the alignment is performed, a composite tooth thickness T50c is obtained. T50c is smaller than T50a and T50b, and is substantially equal to the arc tooth thickness T70 of the tooth 76. The spring 81 is substantially fully compressed in FIG. 8C so as to store approximately the same energy as the spring 81 in the state of FIG.

The small arc tooth thickness of tooth 66 relative to tooth 76 (T60 <T70) prevents the load on tooth 66 from exceeding the load provided by the compression spring of FIG. 8C. In contrast, the teeth 76 bear a load that exceeds the spring load. Limiting the load on the teeth 66 to the spring biasing force typically reduces the reverse bending load based on the random dimensional differences of each member of a tooth pair having a nominally arcuate tooth thickness. Desirably, the wider face width W70 of each tooth 76 is selected to carry a high drive load beyond the spring bias, but the total face width increase (W60 + W70) for gear 50 is the same for all teeth. It is usually less than the increase in tooth width required to withstand the reverse bending load by a scissor gear having a nominal arc tooth thickness.

FIG. 9 is a graph showing the effect of the gear having the reduced arc tooth thickness T60 on the load curve 400 as compared with the gear having the arc tooth thickness T70. Here, the broken line indicates the gear 60, and the solid line indicates the gear 70. Horizontal portion 410 corresponds to the pre-loaded biasing force of gear 50 in the static state of FIG. 8A. The sloped portion 420 corresponds to the loaded condition of the teeth 66, 76 between the static state of FIG. 8A and the aligned position of FIG. 8C. FIG. 8B shows one point along the sloped portion 420. When the load compresses the spring 81 and aligns the teeth as shown in FIG. 8C, the load on the teeth 66 of the gear 60 flattens at the maximum load of the spring 81 and is shown as dashed line 430 in FIG. At the same time, the thicker tooth width W70 of the tooth 76 carries a higher load, shown in FIG. When the gear 70 receives a high load, the load on the gear 60 is limited by the difference between the arc tooth thicknesses (T70-T60), so that the bending load is limited.

Unpleasant noise, such as the hammer of heavy-duty diesel engines, is due to the high impact noise of the gear train associated with these engines. By providing a relatively high bias torque by providing a scissor gear in the gear train, unexpected dramatic changes in loudness have been experienced, including a reduction in overall noise intensity. Here, the "biased torque" refers to the torque given by the scissor gear biased by the spring. The biasing torque is determined by the product of the radial distance from the center of rotation of the gear to the tooth and the force tangentially acting on the circle corresponding to the radius. Typically, the biasing torque varies as a function of the amount of biasing load on the scissor gear. Desirably, the biasing torque is maximized when the gear teeth are substantially aligned against the biasing force. In the aligned configuration of the teeth 66, 76 in FIG. 5, a radial vector T and a force vector F are shown, which can be used to determine the biasing torque of the assembly 58.

It has been found that a maximum deflection torque of at least about 135 N-m (100 ft-lbs) can improve the noise characteristics and strength of the gear train. More preferably, the maximum bias torque is about 270 N-m (200 ft-lbs). More preferably, the maximum bias torque is about 675 N-m (500 ft-lbs).

FIG. 10 is an exploded perspective view of a rotation center 554 of the anti-backlash gear assembly 558 shown as another embodiment of the present invention. Assembly 558 includes a gear 560 having splines 561 on the inner cylindrical surface web 564 of hub 563. The hub 563 has an opening 563a therethrough. Spline 561 is spiraled about center 554 and is inclined with respect to the axis of rotation of gear 560. Hub 563 is integrally connected to web 564. A rim 567 integrally connected to the web 564 is provided with a number of circumferentially arranged teeth 566. The teeth 566 are substantially equally spaced from each other about a center 554 and each have substantially the same size and shape. Gaps 568 between adjacent teeth 566 are also substantially equally spaced from one another and have substantially the same size and shape. Web 564 of gear 560 defines two opposing openings 569.

The assembly 558 also has a gear 570. The gear 570 includes a spline 571 provided on the outer cylindrical surface 572 of the hub 573. Spline 571 is helical about center 554 and is inclined with respect to the axis of rotation of gear 570. The splines 571 are inclined substantially in the same manner as the splines 561 and are combined with each other. The hub 573 is provided with an opening 573a surrounded by the inner cylindrical surface web 574, and has a rotational support relationship with the mounting shaft. Gear 570 includes a web 574 integrally connected to hub 573. Teeth 576 are provided on rim 577 that is integrally connected to web 574. The teeth 576 are substantially equally spaced around the center of rotation 554 and have substantially the same size and shape as one another. The teeth 576 have a gap 578. The gaps 578 are substantially equally spaced from each other and have substantially the same size and shape. That is, the hub 573, web 574, and rim 577 define a cylindrical recess 575. The web 564 defines two opposing threaded recesses 579, each corresponding to one of the openings 569.

A plurality of coil springs 581 are respectively located in the recesses 575 and are substantially equally spaced from each other about a center 554 between the hub 573 and the rim 577; The adjustment devices 590a, 590b each have an adjustment bolt 590 having a threaded stem 592. Stem 592 has a head 594 and an opposing end 593. Adjusters 590a, 590b each include a washer 596 through which stem 592 extends. The head 594 is sized so that the washer 596 does not pass through. The outer diameter of the washer 596 is large enough not to pass through the opening 569. The size of the opening 569 has a sufficient margin with respect to the stem 592 so that the stem 592 can be selectively positioned. The threaded hole 579 is shaped to engage a corresponding one of the stems 592.

Ａ Referring to FIG. 11A, the unaligned position of the assembly 558 is shown, ie, the teeth 566, 576 of the gears 560, 570 are in an unaligned position as in the embodiment shown in FIG. Referring additionally to FIG. 11B, a side elevation view of the assembly 558 in a misaligned position is shown. The spline 561 of the gear 560 engages the spline 571 of the gear 570. For each device 590a, 590b, stem 592 has a corresponding longitudinal axis S1, S2. The stem 592 first engages the threaded hole or recess 579 through the corresponding washer 596 and opening 569. The spring 581 is not substantially compressed in FIGS. 11A and 11B.

Ａ Referring to FIGS. 12A and 12B, a perspective view and a side elevation view of the aligned state of the assembly 558 are shown, respectively. This alignment corresponds to the alignment of assembly 58 in FIG. To align the assembly 558, the stem 592 of the adjustment device 590a, 590b is fully threaded into the recess 579, compressing the spring 581 between the gears 560,570. When the spring 581 is compressed, the tilting of the combination splines 561, 571 causes a lateral movement effect, which translates the translational movement of the devices 590a, 590b into rotational movement of the gears 560,570. When the stem 592 of the device 590a, 590b is unscrewed, the force of the compressed spring 81 causes the gears 560, 570 to rotate in the opposite direction, due to the engagement of the splines 561, 571. Assembly 558 is such that teeth 566, 576 are substantially aligned when stem 592 is fully threaded into recess 579. The aligned orientation of the assembly 558 is configured to provide a selected maximum biasing torque. The distance occupied by the gears 560, 570 along the stem axis S1, S2 varies from the unaligned position D1 in FIG. 11B to the aligned position D2 in FIG. 12B, where D1 is greater than D2. Notably, D2 is the minimum distance occupied by the gears 560, 570 of the assembly 558 along the stem axes S1, S2. That is, gears 560, 570 rotate relative to each other by the distance they occupy along the axis of rotation corresponding to center 554.

Preferably, the number of teeth 566 is the same as the number of teeth 576. The number of spiral splines 561 and 571 is also the same as the number of teeth 566 and 576. Having the same number of teeth and splines eliminates the need to index splines 561 and 571 to ensure that the alignment of teeth 566 and 576 matches the high spring compression. In another embodiment, the openings 569 may be non-circular rather than circular as shown in FIG. In another embodiment, opening 569 is arcuate with an arc around center 554.

The splines 561 and 571 may be provided at positions other than the hubs 563 and 573. As a non-limiting example, one of the gears is provided with an arcuate slot, the inner surface of which is provided with a spline, and is engaged with a spline provided on a flange extending into the slot from the other gear. By arranging one or more pieces of mating splines about the axis of rotation, relative rotation of the gears is possible without surrounding the axis.

As in assembly 58, an alignment device is provided in assembly 558 to selectively align the two gear teeth of the anti-backlash gear assembly against the spring bias of the assembly. The stem 592 is tightened to provide the alignment of FIGS. 12A and 12B to facilitate installation. When the assembly 558 meshes with another gear, for example gear 42, the stem 592 of each device 590a, 590b is loosened, allowing relative rotation of the gears 560, 570, and the backlash of the meshing gear is picked up. Can be This loosening position is the same as that of the embodiment shown in FIGS. 11A and 11B, but preferably, a gap is provided between the head 594 of each bolt 590 and the washer 596 so as to adapt to the change in the backlash state of the corresponding meshing. To do. In one embodiment, when assembly 558 is mounted in mesh with another gear, devices 590a, 590b are removed. This embodiment resists the biasing force by meshing.

Each assembly 58, 558 has an adjustment device having a threaded stem connected to one of the gears and extending along the axis of the stem. The device further includes a head connected to the stem to provide relative positioning to the gear. Typically, assemblies 58, 558 are compatible with respect to other features of the present invention. Further, the assemblies 58, 558 can be used with the anti-backlash gear 200. In another embodiment of the assembly 58, 558, the bolts 90, 590 may be a threaded stem fixed to one of the gears, with a nut screwed into the movable head. The nut is positioned along the stem to selectively engage the other gear. In yet another embodiment, the anti-backlash assembly is omitted. In a variant of the invention, a normal scissor gear is used.

Publications, patent specifications, and patent application specifications cited in this specification are provided as references, but each publication, patent specification, and patent application specification constitutes a part of this specification. .

Although the invention has been illustrated and described in detail in the foregoing description and drawings, these are for purposes of explanation and do not limit the invention. That is, all modifications and alterations within the spirit of the invention should be protected.

FIG. 1 is a front elevation view of an internal combustion engine apparatus shown as one embodiment of the present invention. FIG. 2 is a top plan view of the components of the anti-backlash gear assembly of the embodiment of FIG. FIG. 3 is a top plan view of the components of the anti-backlash gear assembly of the embodiment of FIG. FIG. 4 is a top plan view in which the components of FIGS. 2 and 3 are incorporated in an unmatched relationship with the anti-backlash gear assembly. FIG. 5 is a perspective view of the anti-backlash gear assembly of FIG. 4 in an aligned state. FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 1, showing the idle gear and the adjustable positioning mechanism. 7A and 7B are schematic front elevation views showing different stages of the assembly of the device of FIG. 8A, 8B and 8C are schematic front elevational views showing selected operating states of a portion of the apparatus of FIG. FIG. 9 is a graph showing a relationship related to the operating states shown in FIGS. 8A to 8C. FIG. 10 is an exploded perspective view of an anti-backlash gear assembly shown as another embodiment of the present invention. FIG. 11A is a top plan view of the anti-backlash gear assembly of FIG. 10 in an unaligned configuration. FIG. 11B is a side elevation view of the anti-backlash gear assembly of FIG. 11A. FIG. 12A is a top plan view of the anti-backlash gear assembly of FIG. 10 in an aligned configuration. FIG. 12B is a side elevation view of the anti-backlash gear assembly of FIG. 12A.

Explanation of reference numerals

Reference Signs List 20 internal combustion engine device 40 gear train 50 anti-backlash gear 58 anti-backlash gear assembly 60, 70 gear 65 opening 75 recess 66, 76 gear tooth 67, 77 rim 81 coil spring 90 adjustment bolt 92 stem 94 head 100 idle Gear 120 Positioning mechanism 130 Mounting plate 140 Holding plate 150 Screw fixing device

Claims (23)

A first gear (70, 570) having a number of circumferentially arranged first teeth (76, 576) and a number of circumferentially arranged second teeth (66, 566); A second gear (60, 560), wherein the first gear and the second gear have a common rotation center (54) under the action of a spring bias torque acting between the two gears. , 554) relative to one another, and each of the first teeth (76, 576) is paired with a corresponding one of the second teeth (66, 566) of the compound tooth. Wherein the compound teeth are variable in size according to the force acting against the biasing torque, wherein the anti-backlash gear assembly (58,558) comprises:
The anti-backlash gear assembly wherein the maximum spring bias torque is at least 135 N-m (100 ft-1bs). Each of the first teeth (76, 576) has a first tooth width (W70), each of the second teeth (66, 566) has a second tooth width (W60), The gear assembly of any preceding claim, wherein said first tooth width (W70) is at least about 50% greater than said second tooth width (W60). A bolt (90,590) having a threaded stem (92,592) opposing the head (94,594), wherein the threaded stem (92,592) includes the first gear (70,570) and The head (94,594) is screwed into a hole (79,579) formed in one of the second gears (60,560) and the first gear (70,570) and the second gear (70,570). 60,560) in a supporting relationship to selectively engage the first tooth (76,576) and the second tooth (66,566) for mounting on a gear train against the biasing torque. 3. The gear assembly according to claim 1, wherein said gear assembly is substantially aligned. A first gear (42) having a number of teeth (46) defining a number of tooth grooves;
In a gear train assembly (40) consisting of the first gear (42) and a second gear (50) that meshes, the second gear (50) has a number of pairs of teeth (66, 76). , 566, 576) having two toothed gear members (60, 70, 560, 570), wherein at least one of said pair of teeth has a corresponding one of said tooth grooves. And the two gear members (60, 70, 560, 570) are relatively rotatable about a substantially common center of rotation (54, 554), and at least between the two gear members. A gear train assembly provided with a maximum biasing torque of about 135 N-m (100 ft-1 bs). A third gear (100) meshing with the second gear (50);
A fourth gear (200), which is a scissor gear meshing with the third gear (100);
5. The gear train assembly of claim 4 including a fifth gear (300) meshing with said fourth gear (200). An internal combustion engine having a crankshaft (24), a first camshaft (32), and a second camshaft (34);
A third gear (100) meshing with the second gear (50);
A fourth gear (200), which is a Caesar gear meshing with the third gear (100);
A fifth gear (300) meshing with the fourth gear (200);
The first gear (42) is mounted on a crankshaft (24) and rotates together, the second gear (50) is driven by the first gear (42), and the third gear (100). ) Is driven by the second gear (50), and the fourth gear (200) is driven by the third gear (100) and attached to the first camshaft (32) to rotate together. The gear train of claim 4, wherein the fifth gear (300) is driven by the fourth gear (200) and is mounted on and rotates with the second camshaft (34). Three-dimensional. The gear assembly of claim 1, wherein the maximum biasing torque is at least about 270 N-m (200 ft-lbs). The gear assembly of claim 1, wherein the maximum biasing torque is at least about 675 N-m (500 ft-lbs). (A) preparing a first gear (42);
(B) establishing a first meshing (48) between said first gear (42) and a second gear (50), said second gear being a scissor gear whose effective teeth The dimension (T50) is determined by the first meshing (48);
(C) after establishing the first meshing, select a mounting position of a third gear (100) forming a second meshing (96) with the second gear (50), the mounting position being And determining the backlash of said second mesh (96) as a function of the effective tooth size (T50). The selection changes the mounting position of the third gear (100) by means of an adjustable positioning assembly (120), which positions the third gear (100) on the axis of rotation (104). 10.) The method of claim 9, wherein the method comprises the steps of: (a) providing rotation about a plane substantially perpendicular to the axis of rotation (104); The second gear (50) comprises a pair of gear members (60, 70, 560, 570) connected together by spring biasing torque, the pair of gear members comprising a number of pairs of teeth (66, 66). 76, 566, 576) having a shape that provides a compound tooth having an effective arc tooth thickness (T50) that varies as a function of the first meshing (48). (B1) opposing said spring biasing torque to align each pair of (66,76,566,576) of said pair of gear members of said second gear;
(B2) meshing the second gear (50) with the first gear (42) against the spring biasing torque to form the first mesh (48);
(B3) stopping opposition to the spring biasing torque after the meshing, allowing the first meshing (48) to determine the effective dimension of the tooth pair (66, 76, 566, 576); The gear train assembling method according to claim 9 or 10, wherein: (D) rotatably mounting the third gear (100) at the mounting position;
(E) engaging a fourth gear (200), which is a scissor gear, with a fifth gear (300) to form a third mesh (296);
Engaging the third gear (100) with the fourth gear (200) to form a fourth mesh (196);
Establishing the meshing of the first and second gears includes rotatably mounting the first and second gears (42, 50) to form a first meshing (48). , Said selection includes changing the mounting position of said third gear (100) by an adjustable positioning assembly (120), said positioning assembly (120) connecting said third gear (100). 12. The method according to claim 11, further comprising allowing rotation about the axis of rotation (104) and providing adjustment along a plane perpendicular to the axis of rotation (104). (A) an internal combustion engine;
(B) a first gear (42) rotatably connected to the internal combustion engine and rotating about a first axis (44);
(C) rotatably connected to the internal combustion engine, rotating about a second axis (54), and engaging with the first gear (42) in a first meshing (48) state. A second gear (50), which is a scissor gear;
(D) rotatably connected to the internal combustion engine to rotate about a third axis (104) and to engage the second gear (50) in a second meshing (96) state. , A third gear (100),
(E) an adjustable position to determine the relative position of the third gear (100) to the second gear (50) to a certain extent to control the backlash of the second mesh (96). And a positioning mechanism (120). A fourth gear (200), which is a Caesar gear, rotatably connected to the internal combustion engine and engaged with the third gear (100) in a third meshing (196) state;
A fourth gear (200) and a fifth gear (300) engaged in a fourth meshing (296) state;
The adjustable positioning mechanism (120) positions the third axis (104) relative to the fourth gear (200) to control the backlash of the third mesh (196); 14. The engine device according to claim 13, wherein: The third gear (100) includes a shaft (103) through which a pair of mounting passages (105) pass, and the adjustable positioning mechanisms (120) each define one of the passages (105). Apparatus according to claim 13 or claim 14, including a pair of threaded fasteners (150) therethrough. The positioning mechanism (120) provides relative adjustment along a plane substantially perpendicular to the first, second, and third axes (44, 54, 104). Item 16. The engine device according to any one of the items 15 to 15. The internal combustion engine includes a crankshaft (24), the first gear (42) rotates with the crankshaft (24) to drive the second gear (50), and the second gear (50). 17) The engine device according to any one of claims 13 to 16, wherein the third device drives the third gear (100). A first gear (570) having a number of circumferentially arranged first teeth (576) and a number of first splines (571);
A second gear (569) having a plurality of circumferentially arranged second teeth (566) and a plurality of second splines (561), the first (571) and the second ( 561) are engaged with each other about a common axis of rotation (554), and the first (571) and second (561) splines are inclined relative to the axis of rotation (554). (570) and a second (560) gear to rotate relative to each other, wherein the second teeth (566) are each paired with a corresponding respective one of the first teeth (576). Forming a multiplicity of compound teeth, the dimensions of the compound teeth changing with the relative rotation of the first (579) and second (560) gears;
One or more springs are disposed between the first gear and the second gear to generate a spring bias torque such that the first and second gears can rotate relative to each other about the axis of rotation. Anti-backlash gear assembly. 19. The gear assembly of claim 18, wherein said spring is a coil spring oriented to produce a force acting in a direction substantially parallel to said axis of rotation (554). An adjusting device (590a, 590b) carried on said first gear (570), said adjusting device (590a, 590b) being said first (576) and second (566) against said biasing torque; 20. The gear assembly of claim 19, wherein said gears are selectively aligned. 21. The gear assembly of claim 20, wherein said adjustment device (590a, 590b) includes a bolt (590) having a threaded stem (592) opposing a head (594). The first tooth (576) has a first arc tooth thickness (T70) and the second tooth (566) has a maximum bias torque of at least about 135 N-m (100 ft-1bs). Has a second arcuate tooth thickness (T60), wherein the first tooth thickness (T70) is at least about 0.058 mm (0.002 inches) greater than the second tooth thickness (T60). 22. The gear assembly according to any one of claims 19 to 21. The first gear (570) has a first hub (573) forming a first spline (571), and the second gear (560) forms a second spline (561). Two hubs (563), the dimensions of the compound teeth varying with the distance occupied by the first (570) and second (560) gears along the axis of rotation (554). The gear assembly according to any one of claims 18 to 22, wherein:

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