RU2803217C1 - Matrix gear variable gearbox - Google Patents

Abstract

FIELD: geared variators.

SUBSTANCE: on the drive shaft of the variator there is a disk containing rows of holes, arranged along concentric circles corresponding to gear ratios, with passages between the holes of adjacent rows. With the holes of one of the rows, a gear wheel mounted on the driven shaft is engaged perpendicular to the disk. The pitch of the gear teeth is equal to the pitch of the holes. In this case, the gear wheel can move along the shaft under the influence of the control mechanism in proportion to the number of revolutions of the shaft.

EFFECT: increase in the transmitted torque is achieved.

1 cl, 4 dwg

Description

The invention relates to the field of mechanical engineering and can be used in devices (units) that require an automatic smooth change in the gear ratio from the engine to the actuators, in particular, as automatic transmissions of cars and motorcycles, where they have reached the highest technical level, and other vehicles .

There are two known ways to automatically change the gear ratio and torque from the engine to the actuators:

- transmission using mechanical (gear) gearing (automatic transmission, robotic manual transmission);

- transmission using friction gearing - variator. The main advantage of a variator over gearboxes using gears is the ability to smoothly change the gear ratio with the choice of the optimal one - according to the load and engine speed. Torque is transmitted using friction.

A V-chain variator is known, containing two pulleys and a chain stretched between them. One of the pulleys is connected to the engine crankshaft, the other is kinematically connected to the drive wheels. Each pulley consists of two coaxial disks, made in the shape of a truncated cone, facing each other with small diameters. The discs can be moved or moved apart using a special mechanism. If the discs move, the chain is pushed out; if they move apart, the chain falls inward. The change in the radii along which the chain rotates occurs synchronously - when one pulley increases the radius, the other decreases it - and vice versa. As a result, the gear ratio changes smoothly, and the torque from the drive disk to the driven disk is transmitted by the beveled ends of the chain pins due to the friction force. The use of a chain made it possible to increase the transmitted torque and transmission efficiency by creating greater pressure in the contact area of the chain pins with the pulleys than with the similar use of a metal V-belt (Multtronic CVTs, implemented by the Volkswagen Audi Group and Lineartronic (Fuji Heavy Industries) in collaboration with LUK and installed on Volkswagen, Audi and Subaru cars).

The next step to increase torque, as well as the compactness of the gearbox, was the abandonment of the belt or chain in favor of special rollers.

A toroidal variator is known, which we chose as a prototype, which, like a pulley in an analogue, consists of two identical coaxial disks, one of which is connected to the engine crankshaft, the other is connected to the drive wheels. The disks have tapering parts, forming a body of rotation, directed towards each other, but differ from the pulley halves in the analogue in that the generatrix of the tapering part is not straight, like a cone, but concave, forming (during rotation) a toroidal surface. Mushroom-shaped rollers are sandwiched between the disks, each of which simultaneously touches the toroidal surfaces of both disks with rounded caps. The rollers transmit torque due to friction and can rotate around their axis, as well as tilt in the vertical direction, under the action of a servo drive connected to shaft speed sensors, while the distance between points on a straight line intersecting the rotation axis of the rollers and the toroidal surfaces of both disks - always the same, which means there is no need for a chain (V-belt). The roller, tilting, changes the gear ratio. If the roller is in contact with the drive disk along small radii, then it is in contact with the driven disk along large radii - we get a reduction gear; when rotating along the same radii, the transmission will be direct, if the roller is pressed against the drive disk along a large radius - an overdrive.

Special devices in the toroidal variator create high pressure (up to 10 tons per cm ² ) in the contact area of the rollers with the disks, which increases the friction force and thereby increases the maximum transmitted torque, which means the toroidal variator can be used on more powerful machines. (Nissan's Extroid CVTs installed on the Cedric and Skyline models, as well as the patent of Kristopher John Greenwood, Torortak development, PCT application reference number: GB 199100, patent No. GB 2250326 priority date 90249871 11/16/1990).

Practical designs of CVT transmissions include devices for smooth starting and reversing, a control system, a hydraulic pump for the torque converter that performs the clutch function, or friction discs that perform a similar function.

The main disadvantage of CVTs is that they are frictional (they work due to friction rather than mechanical engagement), and therefore can transmit limited torque, when increased above a certain level, the working surfaces begin to slip and wear out intensively, which means that they are not advisable to use under heavy loads.

The proposed invention solves the problem of replacing the frictional engagement of the drive and driven shafts of a gearbox with a mechanical one, while maintaining the main advantages of a variator over gearboxes.

To achieve the specified technical result in the proposed invention, the functions of a toroidal disk are performed by a disk-shaped cassette rigidly mounted on the drive shaft of the gearbox, having matrix rings corresponding to the gear ratios, containing holes located in concentric circles. Transitional matrix grooves (guides) pass radially through all matrix circles corresponding to various gears. The driven shaft is installed so that its axis is perpendicular to the axis of the drive shaft and intersects with it. A gear wheel is installed on the driven shaft on a sliding spline connection, which has a degree of freedom of movement along the shaft and is engaged with the holes of one of the matrix rings of the cassette.

The principle of operation of a gear-matrix variable gearbox is that the matrix rings of the cassette rotate at the same angular speed and when a longitudinal force is applied to the gear mounted on the driven shaft, it enters the variation mode - into sequential engagement with the holes of the adjacent matrix rings of the cassette through guide passages connecting the holes of adjacent matrix rings of the cassette. In this case, an instantaneous change in the gear ratio occurs without the use of preliminary synchronization mechanisms, which require a time interval for the meshing parts to transition to adjacent gears. Using, for example, a centrifugal mechanism, servos controlled by speed sensors, or other mechanisms to create longitudinal force on the driven gear, allows you to automatically change the gear ratio of a given gearbox, which is selected optimally according to the load and engine speed. In this case, the limitation on the amount of transmitted torque is removed and, thus, it is fundamentally possible to use such a gearbox for a wide range of possible loads.

Depending on the layout requirements, the system can operate in the reverse order - the matrix cassette is mounted on the driven shaft, and the gear wheel is mounted on the drive shaft.

The proposed CVT gear-matrix gearbox is illustrated in the drawing, where in Fig. 1 shows its general view in isometry, Fig. 2 - front view, in Fig. 3 - side view, in Fig. 4 - bottom view.

The variator gearbox contains a housing (12), in which a drive shaft is installed in bearings (5), with a disk-shaped cassette (1) rigidly mounted on it, on the free plane of which holes are made perpendicularly along concentric circles, forming matrix rings (13) . Guide passages (7) are made between adjacent matrix rings. A gear wheel (2) is engaged with the matrix rings of the cassette (13), mounted on a sliding keyed connection on the driven shaft (4), the axis of which is perpendicular to the axis of the drive shaft (14) and is in the same plane with it. The driven shaft (4) is installed in bearings (5), the seats of which are located in the side walls of the housing (12). The central part of the gear (2) is made in the form of a bushing (9), the protrusion of which faces the output end of the driven shaft (4). The driven shaft is equipped with four longitudinal keyways (6) of a semicircular profile, equally spaced from each other. Similar grooves are made on the inner cylindrical surface of the gear (not shown in the figure) so that when they coincide, they form cylindrical cavities in which bearing balls are placed (not shown in the figure), acting as a sliding key, the diameter of which is equal to the diameter of the cylindrical cavity. The exits from the cylindrical cavity on both sides are closed by washer-shaped plugs (10, 16) mounted on the driven shaft (4) and fixed to the gear wheel (2). On the side opposite the protruding bushing (9) of the gear wheel (2) there is a centrifugal mechanism, which includes a compression spring (8) mounted on the shaft (4) and a lever system consisting of two sliding diamond-shaped sections (3) installed on both sides shaft (4). One end of each section is fixed to the plug (16), and the other end is fixed to the shaft (4) and is connected to weights (11), which create a longitudinal force on the gear wheel (2) when the shaft (4) rotates through the movable diamond-shaped sections (3). ).

The operation of a matrix-gear variator gearbox occurs as follows. When torque is transmitted from the engine to the drive shaft (14) with the cassette (1) fixed on it, the gear (2) and the driven shaft (4) engaged with the small matrix ring of the cassette (13) begin to rotate. When the driven shaft (4) picks up the angular speed of rotation, a centrifugal mechanism comes into action, in which, under the action of centrifugal forces, the weights (11) move apart and through the diamond-shaped sliding sections (3) and the centrifugal mechanism, compressing the spring (8), begins to pull the gear wheel (2) along the driven shaft (4) in the direction of increasing the gear ratio, wherein the gear (2) can engage in series with the matrix rings of the cassette (13), reaching the highest gear ratio.

When the external load on the driven shaft (4) increases, the engine speed, and, consequently, the driven shaft (4) decreases, the centrifugal force acting on the gear (2) decreases, as a result of which the spring (8) begins to expand and move the gear (2) in the opposite direction to smaller gear ratios. The optimal gear ratio is set automatically according to the load and engine speed by changing the balance of forces between the centrifugal mechanism (3, 11) and the return spring (8) virtually smoothly due to the absence of time intervals between gear changes.

Claims (1)

A matrix-gear variator, characterized by the fact that a disk-shaped cassette is installed on its drive shaft, containing matrix circles (circles) corresponding to the gear ratios, which are rows of holes located along concentric circles coaxial with the cassette with guide passages connecting the holes of adjacent rows, and with the holes of the matrix circles is in mesh, mounted on the driven shaft perpendicular to the cassette, the pitch of the teeth of which is equal to the pitch of the holes of the matrix circles, having a degree of movement along the shaft carried out by the control mechanism in proportion to the number of revolutions of the shaft, while the gear wheel can sequentially move through the guide passages into engagement with the matrix in circles towards larger or smaller ones, changing the gear ratio of the matrix-gear variator, which is automatically selected optimally - according to the load and engine speed.

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