Thermal control for combustion-powered tools

Abstract

The invention relates to a combustion-powered tool (100, 200, 300) comprising an engine (101, 201, 301), a fuel cartridge (102, 202, 302) and heat transfer means (103, 203, 303) for selectively transferring heat from the engine to the fuel cartridge.

Description

[0001] THERMAL CONTROL FOR COMBUSTION-POWERED TOOLS

[0002] PRIORITY CLAIM

[0003] This application claims priority to and the benefit of French Application No. 2306810, which was filed on June 28, 2023, the entire contents of which is incorporated herein by reference.

[0004] Technical field of the invention

[0005] The present invention generally relates to the thermal control of one or more components of a combustion-powered tool. More specifically, although not exclusively, the present invention relates to the thermal control of a fuel cartridge of a combustion- powered tool.

[0006] Technical background

[0007] Combustion-powered nail and staple driving tools are known and normally comprise a housing enclosing an internal combustion engine. The engine is powered by a pressurized fuel gas canister, also known as a fuel cartridge.

[0008] Summary of the invention

[0009] The present invention aims to provide a more reliable combustion-powered tool.

[0010] The invention relates to a combustion-powered tool comprising a fuel cartridge and a control means for controlling the temperature of the fuel cartridge when in use.

[0011] When fuel is drawn from the fuel cartridge when in use, part of the remaining fuel evaporates, which reduces the temperature of the fuel in the fuel cartridge. One of the consequences of the reduced temperature in the cartridge is an ensuing drop in the pressure of the cartridge and of the fuel it contains.

[0012] The inventors found that this reduced pressure can affect the injection system and, in extreme cases, cause the tool to fail, if the combustion-powered tool is used continuously for long periods.

[0013] The invention therefore provides a more reliable combustion-powered tool, by controlling the temperature of the fuel cartridge.

[0014] The control means can comprise a heat transfer means. The heat transfer means can be used to selectively transfer heat from a heat source to the fuel cartridge. The invention also relates to a combustion-powered tool comprising a heat source, a fuel cartridge and a heat transfer means for selectively transferring heat from the heat source to the fuel cartridge.

[0015] The heat source can comprise an engine. The engine can be configured to receive fuel from the fuel cartridge.

[0016] More specifically, the heat source can comprise an engine configured to receive fuel from the fuel cartridge.

[0017] The control means or heat transfer means can comprise a control mechanism, for example to control the heat transfer between the heat source and the fuel cartridge.

[0018] The control means, heat transfer means or control mechanism can comprise or can operate in a first, connected, state in which heat can be transferred from the heat source to the fuel cartridge. The control means, heat transfer means or control mechanism can comprise or can operate in a second, disconnected state, in which heat transfer is inhibited between the heat source and the fuel cartridge.

[0019] The control means or heat transfer means can comprise a thermal bridge, for example to provide a conductive path between the engine and the fuel cartridge.

[0020] More specifically, the heat transfer means can comprise a thermal bridge to provide a conductive path between the engine and the fuel cartridge.

[0021] The control means, heat transfer means or control mechanism can comprise an actuator. The actuator can be used to selectively close and open the thermal bridge. The actuator can cause the thermal bridge to move into and out of thermal contact with the fuel cartridge or the engine.

[0022] The actuator can move the thermal bridge, for example, between a connected and a disconnected position. A conductive path can be provided between the engine and the fuel cartridge, for example in the connected position. The conductive path can be shut off, for example in the disconnected position.

[0023] More specifically, the heat transfer means can comprise an actuator that moves the thermal bridge between a connected position, in which a conductive path is provided between the engine and the fuel cartridge, and a disconnected position, in which the conductive path is shut off.

[0024] The actuator can comprise a thermal actuator. The thermal actuator can comprise a material that expands and contracts in response to the temperature of the mechanism. For example, the material can be a liquid, a gas, wax or a wax-like substance. The thermal actuator can comprise a thermal actuator made of wax. The thermal actuator can be configured to move the thermal bridge to the disconnected position when the fuel cartridge temperature reaches a preset minimum threshold. The thermal actuator can be configured to move the thermal bridge to the connected position when the fuel cartridge temperature reaches a preset maximum threshold.

[0025] More specifically, the actuator can comprise a thermal actuator configured to move the thermal bridge to the disconnected position when the fuel cartridge temperature reaches a preset minimum threshold and / or to move the thermal bridge to the connected position when the fuel cartridge temperature reaches a preset maximum threshold.

[0026] The thermal bridge can comprise a bimetallic thermal switch. The bimetallic thermal switch can be configured to move the thermal bridge to the disconnected position when the fuel cartridge temperature reaches a preset minimum threshold. The bimetallic thermal switch can be configured to move the thermal bridge to the connected position when the fuel cartridge temperature reaches a preset maximum threshold.

[0027] More specifically, the thermal bridge can comprise a bimetallic thermal switch configured to move the thermal bridge to the disconnected position when the fuel cartridge temperature reaches a preset minimum threshold and / or to move the thermal bridge to the connected position when the fuel cartridge temperature reaches a preset maximum threshold.

[0028] The actuator can comprise an engine, an electromagnet or a solenoid.

[0029] The control means, heat transfer means or control mechanism can comprise a thermal circuit breaker. The thermal circuit breaker can be configured to connect the engine, electromagnet or solenoid to a power source, for example when the fuel cartridge temperature reaches a preset maximum threshold. The thermal circuit breaker can be configured to disconnect the engine, electromagnet or solenoid from the power source, for example when the fuel cartridge temperature reaches a preset minimum threshold.

[0030] More specifically, the heat transfer means can comprise a thermal circuit breaker configured to connect the engine, electromagnet or solenoid to a power source when the fuel cartridge temperature reaches a preset maximum threshold and / or to disconnect the engine, electromagnet or solenoid from the power source when the fuel cartridge temperature reaches a preset minimum threshold.

[0031] The control means or heat transfer means can comprise air circulation means, for example for directing a flow of engine-warmed air towards the fuel cartridge.

[0032] More specifically, the heat transfer means comprise air circulation means for directing a flow of engine-warmed air towards the fuel cartridge. The control means, heat transfer means or air circulation means can comprise a fan, for example to induce an air flow around and / or through the engine. The control means, heat transfer means or air circulation means can comprise a valve, for example to selectively allow air to flow towards the fuel cartridge. The valve can be downstream of the engine.

[0033] More specifically, the air circulation means can comprise a fan to induce air flow around and / or through the engine and a valve downstream of the engine to selectively allow air to flow towards the fuel cartridge.

[0034] The control means, heat transfer means or air circulation means can comprise a processor, which can be configured or programmed to control the heat transfer from the heat source to the fuel cartridge. The processor can be configured or programmed to operate the control mechanism, actuator, fan or valve. The control means, heat transfer means or air circulation means can comprise a memory, which can be operationally connected to the processor. The memory can comprise a computer program or a computer code enabling the processor to control the heat transfer from the heat source to the fuel cartridge. The memory can comprise a computer program or a computer code enabling the processor to operate the control mechanism, actuator, fan or valve.

[0035] The control means, heat transfer means or air circulation means can comprise one or more sensors, for example one or more temperature sensors, which can be operationally connected to the processor. At least one of the sensors can be associated with the fuel cartridge and / or configured to measure the temperature of the fuel cartridge. At least one of the sensors can be associated with the heat source or with the engine and / or configured to measure the temperature of the heat source or of the engine.

[0036] The processor can be configured or programmed to control the heat transfer from the heat source to the fuel cartridge in response to one or more signals received from the sensor(s). The processor can be configured or programmed to operate the control mechanism, actuator, fan or valve in response to one or more signals received from the sensor(s).

[0037] The combustion-powered tool can comprise a nail gun or a stapler.

[0038] For the avoidance of doubt, all the features described herein also apply to any aspect of the invention.

[0039] As part of this application, it is expressly provided that the various aspects, embodiments, examples and alternatives disclosed in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, can be taken separately or in any combination. In other words, all embodiments and / or features of any embodiment can be combined in any way, unless these features are incompatible.

[0040] In order to avoid any ambiguity, the terms “can”, “and / or”, “for example”, and any other similar term used in the present document must be interpreted as not limiting, such that any feature thus described is not necessarily required to be present. Indeed, any combination of optional features is expressly foreseen without departing from the scope of the invention, whether or not they are expressly claimed. The applicant reserves the right to amend any claim originally filed or to file any new claim accordingly, including the right to amend any claim originally filed to depend on and / or incorporate any feature of any other claim, though it is not originally claimed in this manner.

[0041] Brief description of the figures

[0042] Other features and advantages of the invention will become apparent from the following detailed description, which will be understood in reference to the appended drawings, in which:

[0043] [Fig. 1] Figure 1 illustrates a nail gun according to one example, which comprises a temperature control means incorporating a thermal actuator for selectively providing a thermal connection between the engine and the fuel cartridge;

[0044] [Fig. 2] Figure 2 illustrates the nail gun in Figure 1 with the temperature control mechanism in the closed position;

[0045] [Fig. 3] Figure 3 illustrates a nail gun according to another example, which incorporates a temperature control means incorporating a thermal switch for selectively providing a thermal connection between the engine and the fuel cartridge;

[0046] [Fig. 4] Figure 4 illustrates the nail gun in Figure 3 with the temperature control means in the closed position;

[0047] [Fig. 5] Figure 5 illustrates a nail gun according to another example, which comprises a temperature control means incorporating a valve for selectively supplying a flow of engine-warmed air to the fuel cartridge;

[0048] [Fig. 6] Figure 6 illustrates the nail gun in Figure 5 with the valve open; and

[0049] [Fig. 7] Figure 7 illustrates the use of a three-way valve.

[0050] Detailed description of the invention

[0051] Referring now to Figures 1 and 2, a nail gun 100 can be seen, comprising an engine 101 , a fuel cartridge 102 and temperature control means 103 for selectively providing a thermal connection between the engine 101 and the fuel cartridge 102. In this example, the fuel cartridge 102 is mounted in a part of the nail magazine of the nail gun 100.

[0052] The engine 101 comprises a piston (not shown) with an elongated, rigid drive blade movably arranged within a cylinder body (not shown), as is common in the prior art. The fuel cartridge 102 is in the form of a pressurized fuel gas canister, which is fluidly connected to the engine to supply it with fuel gas to drive the engine 101 in the usual way.

[0053] The temperature control means 103 comprises a flexible strip 130 formed from a conductive material to establish a thermal bridge between the engine 101 and the fuel cartridge 102. In this example, the flexible strap 130 is attached at one of its ends to the engine 101 , so that its other end is held towards the fuel cartridge 102.

[0054] The temperature control means 103 also comprises a thermal actuator 131 , which is mounted on and in thermal contact with the fuel cartridge 102. The thermal actuator 131 comprises a cylinder 132, which contains a waxy material configured to expand when it is warmed, and a piston 133 which moves within the cylinder 132 in response to the expansion of the waxy material contained therein. The piston 133 has an end that bears on the flexible strip 130, so that as the temperature of the fuel cartridge 102 increases, the piston 133 moves outwards and pushes the flexible strip 130 out of thermal contact with the fuel cartridge 102, thus cutting off thermal contact between the engine 101 and the fuel cartridge 102.

[0055] Figure 1 shows the nail gun 100 in its pre-operational state, when the temperature of the fuel cartridge 102 is approximately equal to the ambient temperature. This is the normal operating temperature of the fuel cartridge 102, and the waxy material in the cylinder 132 is therefore in an expanded state, so that the piston 133 is extended and the flexible strap 130 is no longer in thermal contact with the fuel cartridge 102.

[0056] When in use, the temperature of the fuel cartridge 102 decreases as fuel is transferred to the engine, as explained above. In this case, the waxy material inside the cylinder 132 contracts, pulling the piston 133 inside the cylinder 132. When the temperature reaches a preset minimum limit, the flexible strip 130 comes into contact with the fuel cartridge 102, as shown in Figure 2.

[0057] When the engine 101 is running, its temperature rises, and when the flexible strap 130 comes into contact with the fuel cartridge 102, a thermal bridge is created between the engine 101 and the fuel cartridge 102. As the temperature of the engine 101 has increased and the temperature of fuel cartridge 102 has decreased, heat is transferred from the engine 101 to the fuel cartridge 102. When the fuel cartridge 102 is warmed by the engine 101 , the wax contained in the cylinder 132 begins to expand and to move the piston 133. When the temperature of the fuel cartridge 102 reaches the preset upper limit, the flexible strap 130 has moved away from the fuel cartridge 102, thus eliminating the thermal bridge. As a result, malfunctions associated with a fuel cartridge 102 that is too cold are attenuated.

[0058] Figures 3 and 4 show a nail gun 200 according to another example similar to the nail gun 100 in Figures 1 and 2, where similar references represent similar features, incremented by 100. The nail gun 200 according to this example differs from the one in Figures 1 and 2 in that the fuel cartridge 202 is housed in the main body of the nail gun 200 and in that the temperature control means 203 comprises a thermal circuit breaker 231 which selectively closes and opens the power supply from a battery 234 to operate a solenoid actuator 232 which causes the flexible strap 230 to engage and disengage from the engine 201 .

[0059] The battery 234 is electrically connected to the solenoid actuator 232 via the thermal circuit breaker 231. In this example, the flexible strap 230 is attached at one of its ends to the fuel cartridge 202 and its other end is adjacent to, but angled away from, the engine 201 . When the thermal circuit breaker 231 is closed, the battery 234 powers the solenoid actuator 232, which deploys a rod 233 on the solenoid actuator 232 and forces the flexible strap 230 into contact with the engine 201 , creating a thermal bridge. When the thermal circuit breaker 231 is opened, the rod 233 retracts and the flexible strap 230 moves away from the engine 101 .

[0060] The thermal circuit breaker 231 is mounted on and in thermal contact with the fuel cartridge 202. The thermal circuit breaker 231 is configured to stay open as long as the temperature of the fuel cartridge 202 is above a preset minimum limit, as shown in Figure 3. When the temperature of the fuel cartridge 202 falls below the preset minimum temperature limit, the thermal circuit breaker 231 closes and forces the flexible strap 230 to engage the engine 201 , as shown in Figure 4. When the temperature of the fuel cartridge 202 returns to a preset maximum temperature limit, the thermal circuit breaker 231 opens and the solenoid actuator 232 retracts the rod 233, thus breaking the thermal bridge between the engine 201 and the fuel cartridge 202.

[0061] Thus, the nail guns 100, 200 in Figures 1 to 4 incorporate temperature control means 103, 203 that operate automatically. In the nail gun 100 in Figures 1 and 2, automatic operation is provided by the thermal actuator 131 , while in the nail gun 200 in Figures 3 and 4, automatic operation is provided by a thermal circuit breaker 231. However, the person skilled in the art will understand that such automatic operation can be achieved using a controller and temperature sensors, for example.

[0062] Figures 5 and 6 show a nail gun 300 according to another example similar to the nail gun 100 in Figures 1 and 2, where similar references represent similar features, incremented by 200. The nail gun 300 according to this example differs from the one in Figures 1 and 2 in that the temperature control means 303 comprises a fan 333 which supplies an air flow around the engine 301 and a valve 332 for closing and opening a passage 330 to supply the air flow to the fuel cartridge 302.

[0063] The temperature control means 303 also comprises a controller 335 and a temperature sensor 336 associated with the fuel cartridge 302 to measure the temperature of the fuel cartridge 302. Both the valve 332 and the temperature sensor 336 are operationally connected to the controller 335. The controller 335 comprises a processor 337 and a memory 338 operationally connected to the processor 337. The memory 338 contains a computer program configured to enable the processor 337 to control the valve 332 in response to signals received from the temperature sensor 336, which indicate the temperature of the fuel cartridge 302.

[0064] When in use, the fan 333 runs to induce a flow of cooling air around the engine 301 and through a series of openings 310 in the main body of the nail gun 300. As long as the temperature of the fuel cartridge 302 measured by the temperature sensor 336 stays above a preset temperature limit, the controller 335 keeps the valve 332 in the closed position, as shown in Figure 5. The fuel cartridge 302 is thus isolated from the air flow. If the temperature of the fuel cartridge 302 measured by the temperature sensor 336 falls below the preset temperature limit, the processor 337 triggers the opening of the valve 332 and part of the air flow previously warmed by the engine 301 is directed towards the fuel cartridge 302. When the measured temperature returns to a value above the preset temperature limit, the processor 337 triggers the closing of valve 332.

[0065] The valve 332 illustrated in Figures 5 and 6 opens the passage 330 to allow part of the air flow to be directed towards the fuel cartridge 302. However, it may be more advantageous to consider a configuration in which the valve 332 is replaced by a three- way valve 432 that redirects the entire flow of engine-warmed air 301 , as illustrated in Figure 7. In this case, the openings 310 in the main body of the nail gun 300 would be closed to the air flow, ensuring that all air is directed to the fuel cartridge 302.

[0066] Throughout the description, the words “comprise” and “contain” and variations thereof mean “including but not limited to”, and are not intended for (and do not exclude) other whole or partial parts, additives or components. Throughout the description, the singular includes the plural, unless the context requires otherwise. In particular, when the indefinite article is used, the specification should be understood to include the plural as well as the singular, unless the context requires otherwise.

[0067] Any features, integers, characteristics, compounds or groups described in connection with a particular aspect, embodiment or example of the invention are to be understood as being applicable to any other aspect, embodiment or example described herein, unless inconsistent therewith.

[0068] List of Reference Numbers

[0069] 100 nail gun

[0070] 101 engine

[0071] 102 fuel cartridge

[0072] 103 temperature control means

[0073] 130 flexi le strip

[0074] 131 thermal actuator

[0075] 132 cylinder

[0076] 133 piston

[0077] 200 nail gun

[0078] 201 engine

[0079] 202 fuel cartridge

[0080] 203 temperature control means

[0081] 230 flexible strap

[0082] 231 thermal circuit breaker

[0083] 232 solenoid actuator

[0084] 233 rod

[0085] 234 battery

[0086] 300 nail gun

[0087] 301 engine

[0088] 302 fuel cartridge

[0089] 303 temperature control means

[0090] 310 openings

[0091] 330 passage

[0092] 332 valve

[0093] 333 fan

[0094] 335 controller

[0095] 336 temperature sensor

[0096] 337 processor

[0097] 338 memory

[0098] 432 three-way valve

Claims

CLAIMS1. A combustion-powered tool (100, 200, 300) comprising a heat source, a fuel cartridge (102, 202, 302) and heat transfer means (103, 203, 303) for selectively transferring heat from the heat source to the fuel cartridge.

2. The combustion-powered tool (100, 200, 300) according to claim 1 , in which the heat source comprises an engine (101 , 201 , 301 ) configured to receive fuel from the fuel cartridge (102, 202, 302).

3. The combustion-powered tool (100, 200, 300) according to claim 2, in which the heat transfer means (103, 203, 303) comprise a thermal bridge to provide a conductive path between the engine (101 , 201 , 301 ) and the fuel cartridge (102, 202, 302).

4. The combustion-powered tool (100, 200, 300) according to claim 3, in which the heat transfer means (103, 203, 303) comprises an actuator which moves the thermal bridge between a connected position, in which a conductive path is provided between the engine (101 , 201 , 301 ) and the fuel cartridge (102, 202, 302), and a disconnected position, in which the conductive path is shut off.

5. The combustion-powered tool (100, 200, 300) according to claim 4, in which the actuator comprises a thermal actuator configured to move the thermal bridge to the disconnected position when the temperature of the fuel cartridge (102, 202, 302) reaches a preset maximum threshold and / or to move the thermal bridge to the connected position when the temperature of the fuel cartridge (102, 202, 302) reaches a preset minimum threshold.

6. The combustion-powered tool (100, 200, 300) according to claim 3, in which the thermal bridge comprises a bimetallic thermal switch configured to move the thermal bridge to the disconnected position when the temperature of the fuel cartridge (102, 202, 302) reaches a preset maximum threshold and / or to move the thermal bridge to the connected position when the temperature of the fuel cartridge (102, 202, 302) reaches a preset minimum threshold.

7. The combustion-powered tool (100, 200, 300) according to claim 4, in which the actuator comprises an engine, an electromagnet or a solenoid.

8. The combustion-powered tool (100, 200, 300) according to claim 7, in which the heat transfer means (103, 203, 303) comprises a thermal circuit breaker configured to connect the engine (101 , 201 , 301), electromagnet or solenoid to a power source when the temperature of the fuel cartridge reaches a preset minimum threshold and / or to disconnect the engine, electromagnet or solenoid from the power source when the temperature of the fuel cartridge (102, 202, 302) reaches a preset maximum threshold.

9. The combustion-powered tool (100, 200, 300) according to claim 2, in which the heat transfer means (103, 203, 303) comprises air circulation means for directing a flow of engine-warmed air towards the fuel cartridge (102, 202, 302).

10. The combustion-powered tool (100, 200, 300) according to claim 9, in which the air circulation means comprises a fan for inducing a flow of air around and / or through the engine (101 , 201 , 301 ) and a valve downstream of the engine for selectively allowing air to flow towards the fuel cartridge (102, 202, 302).

11. The combustion-powered tool (100, 200, 300) according to any of the preceding claims, in which the tool comprises a nail gun or a stapler.

Images