GB1587976A

GB1587976A - Heat generating units for vulcanising belt joints

Info

Publication number: GB1587976A
Application number: GB23830/78A
Authority: GB
Original assignee: BBA Group Ltd
Current assignee: BBA Group Ltd
Priority date: 1978-05-30
Filing date: 1978-05-30
Publication date: 1981-04-15

Description

(54) IMPROVEMENTS IN OR RELATING TO HEAT GENERATING UNITS FOR VULCANISING BELT JOINTS (71) We, BBA GROUP LIMITED of Whitechapel Road, P.O. Box No. 20, Cleck heaton, West Yorkshire, BDl9 6HP, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be parti cularly described in and by the following statement: - This invention relates to portable heat generating units for use in the vulcanising of belt joints in situations where stringent fire precautions are considered necessary, for example as in coal mines.

The general purpose and an example of such a portable heat generating unit is dis closed in Patent Specification No. 1,029,797; in the heating unit of this example the platens for effecting vulcanisation can be heated to a temperature of 100"C by the passage of water therethrough which is heated by a mechanical energy/thermal energy conversion unit.Although it is mentioned in Specification No. 1,029,797 that the heat generating unit is capable of heating the platens, say to a temperature of ]20 C by use of an appropriate water/ ethylene glycol mixture it has been found that with the development of new adhesives for vulcanising belt joints even such a temperature of 120"C is insufficient to effect efficient vulcanisation (an example of an adhesive or bonding compound which requires a vulcanising temperature considerably greater than 100"C is disclosed in our co-pending Application No. 8690176 Serial No. '1 560 891). It is therefore an object of the present invention to provide a portable heat gen erating unit for use in the vulcanising of belt joints at temperatures considerably greater than 100"C, say, in the order of 1 500C and which is suitable for use in situations where conditions of fire and ex plosion risk prevail.

According to the present invention there is provided a portable heat generating unit for use in the vulcanising of belt joints at temperatures greater than 100"C which in cludes a water reservoir; a closed heating system; first pump means for supplying water from the reservoir to the heating system and for maintaining said water in the system under pressure; said closed heat ing system having energy conversion means for converting mechanical energy into thermal energy to effect an increase in the temperature of the pressurised water there in, platen means and second pump means for circulating the water within said heat ing system to heat the platen means for vulcanising a belt joint.

The present invention can be regarded as an improvement in the invention discussed in Specification No. 1,029,797 whereby the water is subjected to heating by the mechanical/thermal energy conversion means and displaced or re-circu lated through the platen means is maintained at a pressure greater than atmospheric, thereby elevating the boiling point of the water and the temperature to which the platens are heated. The energy con version means for converting mechanical energy into thermal energy and ,the structure and arrangement of the platen means are conveniently as described in Specifi- cation No. 1,029,797.

Preferably the closed heating system has a first water circuit and a second water circuit both of which include a common water collecting chamber and of which the first water circuit comprises the second pump means and the platen means and the second water circuit comprises the energy conversion means. In such a preferred system the output from the first pump means is conveniently arranged to communicate with the water collecting chamber.

Desirably the closed heating system in cludes a pressure relief valve which can be adjusted to determine the maximum pressure to which water in the system is subjected by the first pump means and thereby controlling the temperature to which the platens can be heated. Such a pressure relief valve is conveniently located at a position between the output of the first pump means and the aforementioned water collecting chamber.As previously mentioned, belt jointing adhesives or bonding compounds can require a platen temperature in the order of 1500C to effect efficient vulcanisation of the joint and it is therefore preferred that the water in the closed heating system is capable of being pressurised to a pressure in the order of 54 pounds per square inch at which pressure the water is capable of being heated to 1500C to provide a corresponding temperature (assuming that heat losses are negligible) at the platens.

One embodiment of a portable heat generating unit constructed in accordance with the present invention will now be de scribed, by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 illustrates a side elevation of the unit in which, for convenience, the platens have been omitted but such platens can be arranged as described in Specifica tion No. 1,029,797, and Figure 2 is an end elevation of the unit in Figure 1.

The portable heat generating unit has a base plate 1 on which is mounted a flame proof electric motor 2. Also mounted on the base 1 is a heat energy conversion unit 3 having an inlet 4 and an outlet 5. The unit 3 is in the form of a pump and is sub stantially as described with reference to Figures 7 and 8 in Specification No.

1,029,797, whereby the rotor (not shown) of the pump is coupled to be driven by the motor 2.

Mounted above the motor 2 is a water reservoir 6 having an outlet passage 7 which provides an inlet to a pressurising pump 8 mounted on the base 1. The pump 8 is driven by a belt 9 from the motor 2. An outlet from the pump 8 communicates by way of passage 10 with the chamber of a water collecting vessel 11 which forms part of a closed heating system and is common to two water circuits in the system. The first water circuit which includes the cham ber of vessel 11 comprises a passage 12 from that chamber which provides an input to a circulating pump 13 and the output from such pump communicates by way of passage 14 with platen means (not shown) of the first water circuit. The return pas sage 15 from the platen means communi cates by way of a heat exchanger 16 with the chamber of vessel 11.As shown in Figure 2, the circulating pump 13 is mounted on the base 1 and is driven by a belt 17 from the motor 2.

The vessel 11 is mounted on the flanged inlet 4 of the pump 3 so that the chamber of the vessel 11 communicates with the pump chamber. Similarly mounted on the flanged outlet 5 of the pump 3 is a pressure relief valve 18 for the pump 3. The valve 18 is manually adjustable at 19 and the outlet from such valve communicates through passage 18' with the chamber of vessel 11.

The aforementioned second water circuit consequently comprises the chamber of vessel 11, the communication therefrom through inlet 4, the chamber of pump 3, the communication from that chamber through outlet 5, the pressure relief valve 18 and passage 18'.

The pressure relief valve 18 preferably includes a small fixed orifice (not shown) through which water can flow independently of the setting of the relief valve and from the outlet 5 to the passage 18'; the use of such an orifice in the relief valve 18 is described in Specification No. 1,029,797 and serves as an energy conversion means in addition to that of the pump 3.

Located in the passage 10 in communication with the closed heating system is a pressure relief valve 20 which is manually adjustable to control water pressure in the closed system (particularly in the vessel 11) and has an outlet 21 feeding into the reservoir 6.

Also mounted on the base 1 is a fan 22 having an air inlet 23. The fan is driven by the belt 17 from the motor 2. Air from the fan is displaced through a conduit 25 into a casing 26 of the heat exchanger 16.

This casing 26 surrounds the passage 15 and has an air outlet 27. Desirably the casing 26 is packed with copper wire to effect efficient transfer of heat from the water in passage 15 to the air flowing through the casing 26.

In use of the heat generating unit the reservoir 6 is charged with water and the motor operated to drive the pumps 3, 8 and 13 and to drive the fan 22. The pump 8 displaces water from the reservoir 6 into the closed heating system within which such water is circulated through the collecting vessel 11, the platens and the heat exchanger 16 by the pump 13 and from the vessel 11 through the second water circuit having the pressure relief valve 18 by the pumping action of the energy conversion unit 3. During re-cycling of the water through the second water circuit having the energy conversion rotor in the unit 3 and possibly the small orifice associated with the relief valve 18, the temperature of the water continues to rise until eventually it attains a boiling temperature consistent with the pressure in the closed heating system. Simultaneously with the heating of the water in the second water circuit, such water is circulated from the vessel 11 through the first circuit thereby heating the platens which are available for use in vulcanising the adhesive or bonding compound in a belt joint. As aforementioned the maximum temperature of the water in the two water circuits and thereby the temperature to which the platens will be heated, is determined by the water pres sure in the closed heating system and this water pressure is set by appropriate adjust ment of the relief valve 20 from the pump 8 so that excessive pressure in the system is relieved when the valve opens to open communication between the outlet of pump 8 and the reservoir return passage 21.

It will of course be appreciated that the temperature to which the water can be heated by the unit as above described and illustrated will be set to a limit which is considered safe for the various components which are used in the structure of the unit and will also be determined, to a large ex tent, by the performance characteristics of several of the components in the unit such as the power of the motor 2 which serves to drive the rotor in the pump 3 and also the pressurising pump 8.However, it has been determined experimentally that a water pressure of approximately 54 pounds per square inch can be attained within the closed heating system and that with such water pressure p]aten temperatures in the order of 150"C have been reached without difficulty and such platen temperatures have been found suitable for vulcanising adhesives such as those which are the subject of our co-pending Patent Application No. 8690/76 Serial No. 1 560 891.

Similarly to the unit described in Specifi cation No. 1,029,797, the unit as above de scribed with reference to Figures 1 and 2 provides a source of heated air which is conveniently available for drying the ends of a belt before the jointing operation, such heated air being available from the passage 27 as a result of the air being blown by the fan 22 through the heat exchanger 16.

WHAT WE CLAIM IS: 1. A portable heat generating unit for use in the vulcanising of belt joints at tem peratures greater than 100 C which includes a water reservoir; a closed heating system; first pump means for supplying water from the reservoir to the heating system and for maintaining said water in the system under pressure; said closed heating system having energy conversion means for converting mechanical energy into thermal energy to effect an increase in the temperature of the pressurised water therein, platen means and second pump means for circulating the water within said heating system to heat the platen means for vulcanising a belt joint.

2. A unit as claimed in claim 1 in which the closed heating system has a first water circuit and a second water circuit both of which include a common water collecting chamber, the first water circuit comprising the second pump means and the platen means and the second water circuit compris ing the energy conversion means.

3. A unit as claimed in claim 2 in which the output of the first pump means com municates with the water collecting chamber.

4. A unit as claimed in either claim 2 or claim 3 in which the first water circuit includes heat exchange means located downstream of the platen means, said heat exchange means comprising a casing through which air is blown to be heated by the water in the first water circuit, such heated air being available to dry the ends of the belt before they are joined.

5. A unit as claimed in any one of the preceding claims in which the closed heat ing system includes a pressure relief valve which is adjustable to determine the water pressure in said system.

6. A unit as claimed in claim 5 when appendant to claim 3 in which the pres sure relief valve is located between the first pump means and the water collecting chamber.

7. A unit as claimed in any one of the preceding claims in which the water in the closed heating system is capable of being heated to a temperature in the order of 150 C.

8. A heat generating unit substantially as herein described with reference to the accompanying diagrammatic drawings.

9. Belting which includes a belt joint formed by vulcanisation, heat for said vul canisation being derived from a unit as claimed in any one of the preceding claims.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

water in the two water circuits and thereby the temperature to which the platens will be heated, is determined by the water pres sure in the closed heating system and this water pressure is set by appropriate adjust ment of the relief valve 20 from the pump

8 so that excessive pressure in the system is relieved when the valve opens to open communication between the outlet of pump

8 and the reservoir return passage 21.

It will of course be appreciated that the temperature to which the water can be heated by the unit as above described and illustrated will be set to a limit which is considered safe for the various components which are used in the structure of the unit and will also be determined, to a large ex tent, by the performance characteristics of several of the components in the unit such as the power of the motor 2 which serves to drive the rotor in the pump 3 and also the pressurising pump 8.However, it has been determined experimentally that a water pressure of approximately 54 pounds per square inch can be attained within the closed heating system and that with such water pressure p]aten temperatures in the order of 150"C have been reached without difficulty and such platen temperatures have been found suitable for vulcanising adhesives such as those which are the subject of our co-pending Patent Application No. 8690/76 Serial No. 1 560 891.

Similarly to the unit described in Specifi cation No. 1,029,797, the unit as above de scribed with reference to Figures 1 and 2 provides a source of heated air which is conveniently available for drying the ends of a belt before the jointing operation, such heated air being available from the passage

27 as a result of the air being blown by the fan 22 through the heat exchanger 16.

WHAT WE CLAIM IS: 1. A portable heat generating unit for use in the vulcanising of belt joints at tem peratures greater than 100 C which includes a water reservoir; a closed heating system; first pump means for supplying water from the reservoir to the heating system and for maintaining said water in the system under pressure; said closed heating system having energy conversion means for converting mechanical energy into thermal energy to effect an increase in the temperature of the pressurised water therein, platen means and second pump means for circulating the water within said heating system to heat the platen means for vulcanising a belt joint.
2. A unit as claimed in claim 1 in which the closed heating system has a first water circuit and a second water circuit both of which include a common water collecting chamber, the first water circuit comprising the second pump means and the platen means and the second water circuit compris ing the energy conversion means.
3. A unit as claimed in claim 2 in which the output of the first pump means com municates with the water collecting chamber.
4. A unit as claimed in either claim 2 or claim 3 in which the first water circuit includes heat exchange means located downstream of the platen means, said heat exchange means comprising a casing through which air is blown to be heated by the water in the first water circuit, such heated air being available to dry the ends of the belt before they are joined.
5. A unit as claimed in any one of the preceding claims in which the closed heat ing system includes a pressure relief valve which is adjustable to determine the water pressure in said system.
6. A unit as claimed in claim 5 when appendant to claim 3 in which the pres sure relief valve is located between the first pump means and the water collecting chamber.
7. A unit as claimed in any one of the preceding claims in which the water in the closed heating system is capable of being heated to a temperature in the order of 150 C.
8. A heat generating unit substantially as herein described with reference to the accompanying diagrammatic drawings.
9. Belting which includes a belt joint formed by vulcanisation, heat for said vul canisation being derived from a unit as claimed in any one of the preceding claims.