GB2187811A

GB2187811A - Machinery-protection clutch assembly

Info

Publication number: GB2187811A
Application number: GB08704199A
Authority: GB
Inventors: Osmo Sarkilahti; Panu Korri
Original assignee: Rauma Repola Oy
Current assignee: Repola Oy
Priority date: 1986-03-10
Filing date: 1987-02-23
Publication date: 1987-09-16
Also published as: GB8704199D0; FI76034B; JPS62215129A; FI76034C; FI860984A; DE3706972A1; FI860984A0

Abstract

Clutch equipment between the driven shaft (14) and the driving engine (1) of a ship, for example, for the protection of the drive machinery on occasional variations in the loading of the driven shaft (14) supporting a propeller (16), comprises two clutches (7, 11). The connection between the driving shaft (2) and the driven shaft (14) is produced by means of the multi-plate friction clutch (7) during normal loading. When the load increases, a change in the ratio of the speeds of rotation of the primary shaft (2) and the secondary shaft (14) of the clutch (7) beyond a certain value gives an impulse for uncoupling of the clutch (7), whereby the torque transmitted by the hydrodynamic clutch (11) is used as an indication of the loading situation of the propeller. When the obstacle which increased the load is removed and when the ratio of the speeds of rotation of the shaft (2, 14) is again changed, this change gives the impulse to engage the clutch (7) again. (Fig. 2) depicts a modification in which the clutch plates and the blade wheels of the hydrodynamic clutch are located within a common housing. The clutch (11) may be displaced by some other member rotating in a medium or a magnetic field. <IMAGE>

Description

SPECIFICATION Clutch for the protection of machinery The present invention concerns a clutch equipment between the driven shaft and the driving engine for the protection of the machinery on occasional variations in the loading of the driven shaft, which clutch equipment comprises two clutches, wherein the maximum torque transmitted by the second clutch is only a part of the maximum torque transmitted by the first clutch, whereat the connection between the driving shaft and the driven shaft is produced by means of the first clutch during normal loading.

Under exceptional circumstances, ships sailing in arctic conditions may meet with such obstacles of ice as cause damage to the drive machinery of the ship. Various systems have been developed in order to prevent overloading of the engine and to lower the speed of rotation of the engine when the load on the propeller of the ship increases exceptionally.

The object of the present invention is to minimize those detrimental effects that are produced when the propeller strikes against ice or any other obstacle. The clutch in accordance with the invention is mainly characterized in that, when the load increases, a change in the ratio of the speeds of rotation of the primary shaft and the secondary shaft of the first clutch beyond a certain value gives an impulse for uncoupling of the first clutch, whereby the second clutch transmits a torque to the driven shaft, and that, when the obstacle which increased the load is removed and when the ratio of the speeds of rotation of the shafts is again changed, this change gives the impulse to engage the first clutch. Most appropriately, the first clutch is a friction clutch and the second clutch a hydrodynamic clutch.

The device requires no gear transmission or equivalent. Thus, what is concerned is "direct drive", i.e. the transmission ratio is 1:1. The device may, however, also be used in connection with a reduction gear, mainly at the side of its "intake".

The upper limit of the performance ratings of the device is determined mainly by the friction clutch.

The invention and its details will be described in the following with reference to the accompanying drawings, wherein Figure 1 is a schematical side view of one clutch arrangement in accordance with the invention, and Figure 2 is a sectional view of a second clutch arrangement in accordance with the invention.

Fig. 1 shows an embodiment of the arrangement in accordance with the invention.

The main engine 1 is mounted on the shaft 2, on which there is a cogwheel 3. In engagement with the cogwheel 3, there are two cogwheels 4 and 5 of equal size, as compared with each other. On the same shaft 6 with the cogwheel 4, a friction clutch 7 is mounted. The secondary side of the friction clutch is mounted on a shaft 8, on which there is also a cogwheel 9. The friction clutch may be, e.g., a multiple-disc clutch.

On the same shaft 10 with the cogwheel 5, a hydrodynamic clutch 11 is mounted. The secondary side of the hydrodynamic clutch is mounted on a shaft 12, on which there is also a cogwheel 13. The hydrodynamic clutch has two blade wheels fitted one opposite the other, whereby the movement of rotation of the first wheel is transmitted by the medium provided in the clutch to the other blade wheel.

The cogwheels 9 and 13, which are of equal size as compared with each other, are in engagement with the cogwheel 15 mounted on the shaft 14. The propeller 16 driving the ship is also mounted on the shaft 14. The control centre 17 is in connection with the shafts 6 and 8, whose speeds of rotation are sensed by it by means of speed detectors 19.

The control centre controls the hydraulic actuating mechanism 18 of the friction clutch as well as the supply of fuel to the main engine 1.

The equipment illustrated in Fig. 1 operates as follows: The main engine 1 drives the primary shaft 6 of the friction clutch 7 by the intermediate of the wheels 3, 4. When the friction clutch 7 is engaged, it drives the secondary shaft 8 directly. When the friction clutch 7 is engaged, the hydrodynamic clutch 11 does not drive, because there is no lag (difference in speed) between the shafts 10 and 12 as the shafts revolve at the same speed, being driven by the wheels 3, 5 and 15, 13.

When the friction clutch 7 slips, the speeds of the primary and secondary shafts 6, 8 are different. The control centre 17 gives the actuating mechanism 1 8 of the friction clutch a command to tighten the friction clutch 7 to a predetermined constructive maximum value if the speed difference indicated by the speed detectors 19 is little.

When the propeller 16 meets an obstacle, the friction clutch 7 slips. The speed difference between the shafts 6 and 8 is large.

Thereat the control centre 17 gives the actuating mechanism 18 of the friction clutch a command to unclutch the friction clutch. At the same time, the control centre also controls the main engine 1 and reduces its fuel injection and keeps it running at the desired speed of rotation.

When the friction clutch 7 is disengaged and the propeller 16 is jammed by an obstacle, the hydrodynamic clutch 11 produces a torque on the propeller shaft 14 when it transmits the movement of rotation of the shaft 10, by the intermediate of the wheels 13, 15, to the shaft 14. The magnitude of the torque depends on the choice of the hydrodynamic clutch 11.

After the obstacle has been removed from the propeller 16, the ratio of the speeds of rotation of the shafts 6 and 8 is changed.

Thereat the control centre 17 controls the actuating mechanism 18 of the friction clutch to engage the friction clutch 7 and, accordingly, increases the supply of fuel to the main engine 1. The situation has thereby become normal again.

Fig. 2 illustrates a second embodiment of the invention. The hydrodynamic clutch 11 is fitted co-axially with the friction clutch 7.

The discs 20 of the friction clutch 7 are attached to the housing 21 of the clutch, which said housing revolves along with the shaft 2 connected to the main engine, whereas the discs 22 are attached to the shaft 14, which is connected to the propeller.

The discs 20 and 22 are pressed together by increasing the pressure in the resilient annular member 23.

The first blade wheel 24 of the hydrodynamic clutch 11 is attached to the housing 21 of the friction clutch 7 and revolves along with the housing. The second friction wheel 25 of the hydrodynamic clutch is fixed permanently to the shaft 14. The joint between the blade wheel 25 and the blade wheel 24 as well as the joint between the blade wheel 25 and housing 21 are slipping joints.

The control centre 17 operates in the same way as in the embodiment shown in Fig. 1.

When the friction clutch 7 is engaged, the shafts 2 and 14 revolve at the same speed.

When the propeller meets an obstacle, the friction clutch 7 slips, whereby the speed detectors 19 ascertain the speed difference between the shafts 2 and 14, and the control centre 17 gives the actuating mechanism 18 a command to disengage the friction clutch.

Thereat the blade wheel 24 of the hydrodynamic clutch 11, which revolves along with the housing 21 and with the shaft 2, transmits a torque, which is an indication of the propeller loading situation. Upon removal of the obstacle, the speed of rotation of the shaft 14 increases and the control centre gives the actuating mehcanism a command to engage the friction clutch again. The supply of fuel to the main engine is also controlled in the same way as in the embodiment shown in Fig. 1.

The invention is not confined to the embodiments described above only, but it may show variation in many ways within the scope of the patent claims.

The system may also be controlled manually, without a control centre unit 17.

The clutch equipment may also be used for other applications, besides in a ship. It is suitable for any application whatsoever in which the drive machinery must be protected during occasional increase in load. The drive machine may also be some other machine, besides a combustion engine.

In stead of a hydrodynamic clutch, it is also possible to use some other member revolving in a medium or in a magnetic field for the transmission, for example a generator.

Claims

1. Clutch equipment between the driven shaft (14) and the driving engine (1) for the protection of the machinery on occasional variations in the loading of the driven shaft, which said clutch equipment comprises two clutches (7, 11), wherein the maximum torque transmitted by the second clutch (11) is only a part of the maximum torque transmitted by the first clutch (7), whereat the connection between the driving shaft (2) and the driven shaft (14) is produced by means of the first clutch (7) during normal loading, and by means of the second clutch (11) during loading higher than normal, characterized in that, when the load increases, a change in the ratio of the speeds of rotation of the primary shaft (6 or 2) and the secondary shaft (8 or 14) of the first clutch (7) beyond a certain value gives an impulse for uncoupling of the first clutch (7), whereby the second clutch (11) transmits a torque to the driven shaft (14), which said torque is an indication of the loading situation of the propeller, and that, when the obstacle which increased the load is removed and when the ratio of the speeds of rotation of the shafts (6 or 2; 8 or 14) is again changed, this change gives the impulse to engage the first clutch (7).

2. Clutch equipment as claimed in claim 1, characterized in that, when the first clutch (7) is disengaged, an impulse is also given to reduce the operating power of the drive engine (1), and, correspondingly, when the first clutch (7) is re-engaged, an impulse is also given to increase the operating power of the drive engine (1).

3. Clutch equipment as claimed in claim 1 or 2, characterized in that the first clutch and the second clutch (7, 11) are placed on parallel shafts (6, 8 and 10, 13) placed side by side.

4. Clutch equipment as claimed in claim 1 or 2, characterized in that the first and the second clutch (7, 11) are placed on coaxial shafts (2, 14).

5. Clutch equipment as claimed in any of the claims 1 to 4, characterized in that the first clutch (7) is a friction clutch.

6. Clutch equipment as claimed in any of the claims 1 to 5, characterized in that the second clutch (11) is a hydrodynamic clutch.

7. Clutch equipment substantially as hereinbefore described with reference to the accompanying drawings.