GB2164410A

GB2164410A - Drive disconnecting device

Info

Publication number: GB2164410A
Application number: GB08521206A
Authority: GB
Inventors: Osmo Aulis Untamo Sarkilahti
Original assignee: Rauma Repola Oy
Current assignee: Repola Oy
Priority date: 1984-09-12
Filing date: 1985-08-23
Publication date: 1986-03-19
Also published as: GB8521206D0; FI843577L; FI843577A0; GB2164410B; FI71821C; FI71821B; DE3531724A1; JPS6192341A

Abstract

Planetary gearing (1) transmits drive between a driving shaft (2) and a driven shaft (4). On overload of the driven shaft, a friction brake (9) on a brake shaft (8), driven by one of the elements of the gearing, slips and allows the drive to be interrupted, the engine torque also being reduced, whereupon a hydrodynamic brake (10) is brought into action on removal of the cause of the overload. A feedback controller (12) senses (11) rotation of the brake shaft (8) on overload, reduces engine fuel injection (15), and gradually releases the friction brake (9), the hydrodynamic brake (10) taking over. There are preferably two or more brake shafts. The carrier or the sun may alternatively be braked. The invention is particularly used in preventing overload damage in icebound icebreaking ships. <IMAGE>

Description

SPECIFICATION A clutch for protection of the mechanism and regulating the output of a propulsion engine This invention concerns a clutch between a driven shaft and a propulsion engine for protection of the mechanism and for regulating the output of the propulsion engine whilst the driven shaft loading changes at random, which clutch comprises planet gearing set between the propulsion engine driving shaft and the driven shaft, the annulus, sun gear or the planet body of which is restrained from rotational movement during normal loading on the driven shaft and when loading on the driven shaft increases at random and the relationship between the revolution speed of the propulsion engine drive shaft and that of the driven shaft changes the planet gearing, annulus, sun wheel or planet gear body, which is normally restrained, then makes a rotational movement.

Vessels operating in arctic conditions may, under exceptional circumstances, encounter such ice barriers as to cause damage to the propulsion engines of the vessel. Various systems have been developed for preventing overloading of the engines and for lowering the revolution speed when loading on the vessel screw increases exceptionally. Such systems have been described, for example in the DE publications 1 949 939, 2 913 375 and 3 026 581.

The purpose of this invention is to minimize the detrimental effects that are caused when the screw hits ice or other obstacles. It is characteristic to the clutch according to the invention that the brake shaft is furnished with two brakes and its rotation gives an impulse for the lowering of the propulsion engine output and for relief of the first brake whereupon when the first brake is released and the second brake in starting to brake sets up a torque proportional to the driven shaft torque which reduces as the obstacle which is increasing loading is removed and this brings about a torque in the brake shaft and driven shaft and the change in revolution speed giving an impulse for raising the output power of the propulsion engine and tightening of the first brake.The annulus of the planet gearing is most suitably restrained during normal loading; but it is freed within limitations as the driven shaft is loaded over the permissible limit and becomos retained. A brake shaft can be fastened to the annulus of the planet gearing the simultaneous rotation of which transmits an impulse for lowering the propulsion engine output.

The clutch utilises planet gear transmission.

With the aid of constraining or releasing the external circumference, rotation or stopping of the screw can be achieved. By braking at the outside circumference a torque, proportional to the magnitude of propeller shaft braking is obtained with the screw as locked.

In addition to the friction brake the system is furnished with a hydrodynamic brake. The friction brake can thus momentarily counteract even a large power surge and it is in this way advantageous in the beginning stages of braking, for example when an ice barrier stops the screw and at the clutch stage when an obstacle is removed. Because of difficulty in cooling the friction brake and uneven braking it is more advantageous to use for longer braking periods a hydrodynamic brake with the aid of which and efficient cooling a longer period at limited power levels can be counteracted and an even braking torque can be achieved.

In the system according to the invention there is only excess power loss when the brake shaft rotates. In addition the heat transferred in hydrodynamic cooling can be easily utilised for heating.

The invention and its details are described in the following by referring to the accompanying drawings in which: Figure 1 presents schematicaliy a clutch arrangement according to the invention as seen from the side, Figure 2 presents a cross-section of a planet gear used in the clutch, Figure 3 presents a cross section on line A-A of Fig. 2, Figure 4 presents a cross section of an alternative planet gear.

The clutch according to the invention comprises planet transmission 1, which is driven by the output shaft 2 of the vessel propulsion engines (not shown in the drawings). The planet transmission in its turn drives the shaft 4 of the vessel screw 3.

In Figs. 2 and 3 the construction of the planet gear is illustrated in more detail. As an extension of shaft 2 is the sun wheel 5 of the planet gear the movement of which is transmitted to the planet gearing 6 and on to the shaft 4. The external surface of the planet gearing annulus 7 is connected by gear transmission to two brake shafts 8, which are symmetrically located relative to he annulus.

The brake shaft is furnished with a friction brake 9 and with hydrodynamic brake 10 (Fig.

1). The friction brake 9 can for example be a disk brake or a drum brake. The hydrodynamic brake 10 has two impellers 16 and 17 fitted opposite to one another. The construction of the hydrodynamic brake corresponds to the in-themselves known hydrodynamic flow clutch or the fluid clutch. Rotational movement of impeller 17 is prevented whereupon it brakes the rotation of the opposite impeller 16 through the agentbody between the impellers. The sensor 11 transmits revolution count data to the feedback control station 12. The sensor 13 transmits the friction brake torque to the feedback control. The feedback control station is linked to the pressure regula tion valve system 14 hydraulically clamping and releasing the friction brake and also to the vessel engine fuel feed 15.

In normal running conditions the feedback control station 12 governs the friction brake 9 through the valve system 14 so that rotational movement of the brake shaft is prevented.

Movement at external circumference 7 of the annulus is then also prevented. Movement of the drive shaft 2 is transferred through the rotating movements of the planet gearing 6 to shaft to be driven 4. Then the screw 3 rotates with a revolution speed corresponding to the main engine revolution speed. Tightening of the friction brake 9 corresponds to the main engine screw torques as the case may be.

The random increase in screw torque attributable to the slow rotation of the brake shaft 8 gives rise to additional clamping of the friction brake 9 through the feedback control station 12, but not however above the previously defined maximum screw torque.

If the screw 3 is icebound the friction brake 9 is not able to withstand the over large torque. The brake shaft 8 then starts to rotate.

The feedback control station 12 receives the brake shaft rotation data and reduces the propulsion engine fuel injection 15, preserving however - unless otherwise desired, the revolution speed of the main engine.

At the same time the rotation of the brake shaft 8 sets up a braking torque in the hydrodynamic brake 10 and the feedback control station 12 correspondingly relieves and finally releases the friction brake 9. The propulsion engine is then only braked by hydrodynamic brake 10.

When the screw does not rotate because of ice obstruction the propulsion engine runs idle.

The extent of the output depends on the value of braking imposed by the hydrodynamic brake. The torque on propeller shaft 4 then has a value the magnitude of which depends on the extent of braking at braking shaft 8.

As the obstruction of the screw lessens or is removed and the screw becomes free to rotate, the revolution speed of the brake shaft 8 changes. The feedback control station 12 then initiates clamping at the friction brake 9, until the brake shaft 8 stops rotating. At the same time the control station also raises the fuel injection 15 to the original value. The return has then been made to the normal state.

The invention is not only limited to the application hitherto presented, but can vary in many ways within the bounds of the patent

Claims

claims. The system can also be controlled manually without the feedback control station 12. The clutch can also be used in other than shipboard applications. It is suitable to any application in which, during a temporary increase of loading, the driving engine must be protected. The driving engine can be other than a combustion engine. The number of brake shafts braking the external circumference of the planet gear can vary. Some other element, a generator for example, rotating in an intermediate agencyor magnetic field, can be used for braking instead of a hydrodynamic brake. The planet gear transmission can also be constructed so that as the braking part the body of the planet wheel is used, or using the sun wheel when the annulus uses the directly driven shaft or vice versa in elevated transmission use. A solution in Fig. 4 has been presented in which with the aid of the brake shaft 8 the annulus is held in position by the body 18 carrying the planet wheels 6. The sensor 11, which monitors the screw loading, can also be combined directly with the propeller shaft instead of the position at brake shaft 8. In general the sensor number type, position, and feedback control station program is dependent on the clutch operational application. CLAIMS

1. A clutch between the driven shaft (4) and the propulsion engine for the protection of the mechanism and for regulating the propulsion engine output while the loading on the driven shaft (4) varies randomly, the clutch of which consists of the planet gear arrangement (1) between the propulsion engine driving shaft (2) and the shaft (4), the rotation of the annulus (7), the sun wheel (5), or the planet body (18) of which is prevented from rotating with the aid of the brake shaft (8) connected to it during the time of normal loading on driven shaft (4), then when the loading on the driven shaft (4) randomly increases and the ratio between the revolution speed of the propulsion engine shaft (2) and that of the driven shaft (4) changes the normally restrained annulus (7), the sun wheel (5) or the planet body (18) rotates, characterised in that, the brake shaft (8) is furnished with two brakes (9, 10) and the rotation of which gives an impulse for reducing the output of the propulsion engine and for relieving the first brake (9), when upon the first brake (9) releasing and the second brake (10) starting to brake a torque is set up in the driven shaft proportional to the torque of the second brake (19) which reduces as the obstacle increasing loading is being removed and thus brings about a change in the torque and in the rotation speed of the driven shaft (4) and the brake shaft (10), giving an impulse to it for raising the operating output of the propulsion engine and for clamping the first brake (9).

2. A clutch according to Patent Claim 1 characterised in that a friction brake is used as the first brake and the second brake (10) includes a rotating element (16) in an intermediate agent body or magnetic fielsd.

3. A clutch according to Patent Claim 2, characterised in that as the second brake a hydrodynamic brakd (10) is used which only brakes on rotation of the brake shaft (8).