RU32846U1 - Differential helical mechanism - Google Patents

Description

IPC 7 F 16 H 25/06; 25/18; 25/20

DIFFERENTIAL SCREW MECHANISM

The proposed utility model relates to the field of precision instrumentation, and in particular to devices that provide small movements of the driven link (executive body).

A device analogous to the implementation of small movements 1, comprising a housing, a screw and a nut with a pin included in the groove of the housing. The screw is a shaft with two threads with slightly different steps.

The main disadvantage of this device is the simultaneous rotation and longitudinal movement of the drive link, in this case the screw, which makes it difficult to organize its rotation from the drive in order to automate the process of controlling the executive body. In addition, this device has significant longitudinal dimensions.

The closest to the proposed utility model in technical essence is a differential screw mechanism 2, comprising a screw with a lead, a body with an internal thread and a guide, a nut with internal and external threads with slightly different steps, while the pitch of the internal thread of the nut coincides with the pitch of the screw, and the pitch of the external thread of the nut coincides with the pitch of the internal thread of the housing.

The main disadvantage of the prototype, as well as the analogue, is the simultaneous rotation and longitudinal movement of the drive link, in this case, the nut, which, of course, complicates the organization of its rotation from the drive in order to automate the process of controlling the executive body. In addition, with the longitudinal movement of the screw there is sliding friction, which significantly reduces the efficiency of the differential screw mechanism.

topics of automatic control of the position of the moving object, as well as improving the efficiency of the differential screw mechanism.

To solve these problems, a differential screw mechanism is proposed, which contains a housing with an internal thread and a guide, a screw with a lead, a nut with internal and external threads with slightly different steps, while the pitch of the inner thread of the nut coincides with the pitch of the screw, and the pitch of the external thread nuts with a pitch of the internal thread of the housing.

However, unlike the prototype, it is equipped with a base, gear, a second lead and a second guide, while the first guide is placed on the base, and the second is mounted on the gear, the second lead, kinematically connected to the first guide, is rigidly connected to the screw with the screw the first leash kinematically connected with the second guide, and the gear connected to the housing, made with the possibility of rotation. Leashes can be equipped with rolling bearings, with two of them rolling along the first guide, and the other two along the second.

The essence of the utility model is that due to the presence of additional leash and guide, gear and base, the driving link (housing with gear) carries out only rotational movement, which provides convenient automation of the process of moving the executive body.

In addition, leashes using rolling bearings increase the efficiency of the mechanism.

The principle of operation of the proposed differential mechanism is illustrated by drawings.

In FIG. 1 shows a differential screw mechanism (side view).

Pa fig. 2 shows a cross section of a differential screw mechanism along the axis of movement of the screw.

The differential screw mechanism (Figs. 1 and 2) contains screw 1, a first lead 2, a second guide 3, two half shafts 4, two bearings 5, two bushings 6, a nut 7, a second lead 8, two half shafts 9, two bearings 10, two

bushings 11, the first guide 12 (Fig. 1) the housing 13 with the gear 14, the sleeve 15, two bearings 16, the base 17 (Fig. 1), the threaded ring 18 (Fig. 1).

The screw 1 is rigidly connected to the first leash 2, which has two axles 4 with bearings 5, which are kinematically connected to the second guide; to it 3, mounted and secured, for example, by screws on the gear 14 with the possibility of adjusting the play between the bearing 5 and the guide; to it 3 and ensure smooth mixing in nut 7. Nut 7 has internal and external threads with slightly different steps, the pitch of the internal thread coincides with the pitch of screw 1, and the pitch of the external thread coincides with the inner pitch of the housing 13. Gear 14 is connected to the housing 13, with the possibility of rotation in the bearings 16 installed in the base 17. The ring 15 is designed to eliminate axial play in the bearings 16, and the ring 18 for securing the bearings 16 in the base 17. The second lead 8 is rigidly connected to the nut 7 with two axles 9 and two bearings 10, which are kinematically connected with the first guide 12. The bushings 11 are designed to secure the bearings 10 on the axle shafts 9. The first guide 12 is located on the base 17. One of the axle shafts 4 and 9, respectively, is made with an eccentricity for selecting the play row bearings and guides.

The device operates as follows.

When the gear 14 is rotated (for example, from an electric drive), along with the housing 13, the Si nut 7 is progressively moved along the axis in accordance with the following dependence: Ф

where f is the angle of rotation of the gear with the housing, glad.

ti is the pitch of the internal thread of the housing (or external thread of the nut), mm;

Simultaneously with the gear 14, the guide 3, which is fixed on it, rotates, which rotates the leash 2, which protects the screw 1 from turning.

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Because and in the case, and in the nut and in the screw, the thread direction is the same (either right or left), then screw 1 will progressively move 82 in the direction opposite to the direction of movement of nut 7 in accordance with the dependence:

S2: f 42,

where t2 is the pitch of the screw (or internal thread of the nut).

As a result, the movement S of the screw relative to the fixed base 17 will be equal to:

S Si-S2 (ti-t2) By selecting the appropriate steps ti and t2, very small displacements of the screw can be achieved when the gear rotates one revolution.

Thus, the proposed differential screw mechanism, unlike the prototype, allows you to expand the functionality associated with providing work in automatic control systems of the position of the moving object, as well as increase the efficiency of the mechanism.

Sources of information

1. "Reference designer of optical-mechanical devices under the general editorship of V.A. Panova, L., Mechanical Engineering. 1980, p. 498 (analog).

2 Litvin F.L. “Design of mechanisms and parts of devices. L., Engineering. 1973, p. 417 - 418 (prototype).

Claims (2)

1. A differential screw mechanism comprising a housing with an internal thread and a guide, a screw with a lead, a nut with internal and external threads with slightly different steps, while the step of the internal thread of the nut coincides with the step of the screw, and the step of the external thread of the nut coincides with the step of the internal thread case, characterized in that it is equipped with a base, gear, a second leash and a second guide, while the first guide is placed on the base, and the second is mounted on the gear, the second lead is rigidly connected to the nut, kinematically connected to the first guide, the first lead is rigidly connected to the screw, kinematically connected to the second guide, the gear being connected to the housing rotatably. 2. The differential screw mechanism according to claim 1, characterized in that the leads are provided with rolling bearings, while two of them roll along the first guide, and the other two along the second.