RU2071627C1 - High-speed mechanism shaft support - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: shaft support of high-speed mechanism has at least three bearings mounted in housing on journals of eccentric shafts. Bearings are arranged so that their outer races are held tight against high-speed shaft journal. Each eccentric shaft is provided with lever. Levers are joined in tandem in parallel pairs by means of cleats mounted on pains fixed in levers. One of levers is hinged through control rod to screw installed on housing. Screw is provided with torsional spring one of whose ends is secured on screw and other, on housing. Spring builds up torque that drives screw into housing to create tractive force imparting torque to eccentric shaft through control rod, lever, and cleat. This torque provides for permanent and uniform pressure of bearings against supporting journal of high-speed shaft. Forces due to unbalance of mass on high-speed shaft are finally taken by screw-to-housing joint. This reduces vibration thrusts and radial forces acting on bearing. EFFECT: improved mechanical endurance of high-speed shaft supports. 3 dwg

Description

 The invention relates to mechanical engineering, in particular to the design of high-speed mechanisms.

A known shaft support of a high-speed mechanism, comprising a housing, at least three bearings placed in it on eccentric shafts, and a device for pressing bearings to the support neck of a high-speed shaft, made in the form of pulleys mounted on eccentric shafts, and a flexible rod mounted on one a pulley sequentially covering other pulleys and connected by a tension spring to the mechanism body [1]
The disadvantage is that in this design additional forces act on the bearings from the traction of the spring, which should be greater than the centrifugal forces arising on the high-speed shaft from unbalanced mass. Excessive and constant influence of additional forces on bearings reduces the durability of the shaft support.

 A bearing assembly of a high-speed electric machine is known, comprising at least three bearings placed in a shield around a circle on eccentric shafts and a mechanism for pressing bearings to the journal of the rotor shaft, made in the form of levers mounted on eccentric shafts and connected in series by plates mounted on the axes fixed in the levers, while one of the levers is connected by a tension spring with a shield. The levers of each pair are equal to each other, and the distance between the axes in each of the plates is equal to the distance between the centers of the respective shafts in the shield [2] prototype.

 The design drawback is that additional forces from the tensile spring act on the bearings to overcome the centrifugal forces acting from unbalanced masses on the rotor shaft. This reduces bearing life.

 The objective of the invention is to increase the durability of the shaft support.

 The essence of the invention lies in the fact that in the shaft support of a high-speed mechanism, comprising a housing, at least three bearings placed therein on eccentric shafts, a device for pressing bearings against the support neck of a high-speed shaft, made in the form of levers pairwise equal in length, mounted on eccentric shafts and connected in series with each other by plates mounted on axles fixed in levers, with a distance between the axes in each of the plates equal to the distance between the centers of eccentric shafts in the housing, a screw mounted in the housing, and a rod pivotally connected to one of the levers with a screw equipped with a torsion spring, one end of which is mounted on the screw and the other on the housing, as a result, it was possible to reduce the radial force acting on the bearings, and accordingly increase the durability of the work.

 In FIG. 1 schematically shows a shaft support of a high-speed mechanism, general view; in FIG. 2 a section A-A of FIG. 1 using three bearings; in FIG. 3 a section A-A of FIG. 1 using four bearings.

 The shaft support comprises three bearings 1, which are placed in the housing 2 on the necks 3 of the eccentric shafts 4 installed in the housing 2. The bearings 1 are arranged in a circle so that their outer rings 5 are pressed against the support neck 6 of the shaft 7 of the mechanism 8. Each eccentric shaft 4 equipped with a lever 9. The levers 9 are connected in series pairwise-parallel with each other by plates 10 mounted on the axles 11, which are mounted on the levers 9. One of the levers 9 is pivotally connected by a rod 12 with a screw 13 mounted on the housing 2. The screw 13 is equipped with a torsion spring 14 one horse 15 which is fixed on the screw 13 and the other end 16 on the housing 2.

 The torsion spring 14 creates a torque on the screw 13, which, as the bearing journal 6 of the shaft 7 and the outer rings 5 of the bearings 1 wear out, moves the rod 12, levers 9 and plates 10, the advanced torque on the eccentric shafts 4, thereby compressing the bearings 1 to the bearing the neck 6 of the shaft 7. In this case, the clamping force is maintained and the position of the geometric axis of the shaft 7 remains constant, since each successive pair of levers 9 mounted on eccentric shafts 4, connected by a plate 10 on the axes 11, is a four-link mechanism, in which the chaga 9 are equal and parallel, and the distance between the axes 11 in the plate 10 is equal to the distance between the centers of the corresponding eccentric shafts 4 in the housing 2. In the first pair of levers 9 (Fig. 2), the distance "B" between the axes 11 in the plate 10 is equal to the distance "B '' between the shafts 4 in the housing 2. In the second pair of levers, respectively, the distance "C" is equal to the distance "C '". This ratio of sizes and the position of the levers and plates relative to the eccentric axes in the housing obeys the parallelogram rule, i.e., when one eccentric shaft 4 is rotated, the other eccentric shaft rotates by the same angle. Since all the eccentric shafts in the support are successively connected by similar mechanisms, when the support journal of the high-speed shaft and the outer surfaces of the bearings wear during operation, the bearings are pressed against the journal of the shaft at the same time with the same effort. In this case, the pressure force of the bearings, i.e. its value is required only to overcome the forces of unbalanced masses on the high-speed shaft, ultimately it is perceived not by the spring, but by the self-braking connection of the screw with the body. The torsion spring, screwing the screw into the housing, creates a traction force, which is transmitted to the eccentric shaft 4.

 To increase the allowable dynamic load of the support, not three, but four or more bearings are used (Fig. 3).

 The application of the proposed design of the shaft support provides an increase in the durability of the mechanism, since the radial forces acting on the bearings are significantly reduced.

 So, for example, with an unbalanced mass on a high-speed shaft equal to 0.5 gcm at 60,000 rpm, the centrifugal force acting on the bearings is about 180 kg. At the same time, so that with such a force the bearings do not move away from the shaft journal, a counteracting force is required, which must be obviously greater than the centrifugal force. In the analogue and in the prototype, this force was created from the efforts of the tension spring, which, through the levers, turning the eccentric shafts, pressed the bearings to the support neck of the high-speed shaft. In the case of an unbalanced mass, for example, equal to 0.05 gsm for the same 60,000 rpm, and on the same shaft this force is 18 kg, which is an order of magnitude lower than the previous force. As a result, in the first example, the spring tension force needs to be done ten times more than in the second example.

 In the proposed design of the shaft support, it is enough to just slightly press the bearings against the support neck of the high-speed shaft, i.e. select all the clearances in the device for compressing bearings for all cases, since the forces acting from an unbalanced mass are ultimately perceived by the connection of the screw with the housing, and since this connection is self-braking, practically this force is perceived by a rigid system. At the same time, vibration loads are reduced, since instead of a "floating" system, a rigid load sensing system is proposed.

 Application of the design increases the durability of the shaft support of the high-speed mechanism by 3-4 times.

Claims (1)

 A shaft support of a high-speed mechanism, comprising a housing, at least three bearings placed in it on eccentric shafts, a device for pressing bearings to a shaft journal, made in the form of levers mounted on eccentric shafts and connected in series by pairs of plates mounted on axles fixed in levers, the levers of each pair are equal in length along each other, and the distance in each of the plates between the axes is equal to the distance between the centers of the corresponding eccentric shafts in the housing, screw, mounted in the housing, and a spring, characterized in that one of the levers is pivotally connected by a rod to the screw, the spring is made in the form of a torsion spring, one end of which is mounted on the screw, and the other end on the housing.

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