Compressor systems for puncture repair kits

Abstract

The invention relates to a compressor system for a puncture repair kit comprising a piston (3) which is driven by a motor (9) via a crank mechanism and a cylinder main body (1) having a pump chamber (6) in which the piston (3) is mounted such that it can move from a bottom dead point to a top dead point for compressing air.

Description

[0001] Description

[0002] Compressor systems for breakdown assistance kits

[0003] The invention relates to a compressor system for a breakdown kit, comprising a piston driven by a motor via a crank mechanism with two gears, and a cylinder main body having a pumping chamber in which the piston is mounted for movement from a bottom dead center to a top dead center for compressing air. Furthermore, the invention relates to a breakdown kit comprising a compressor system and a method for sealing a vehicle tire.

[0004] Compressor systems for breakdown kits of the type described above are known for use with car tires. Such breakdown kits are designed to provide the volume of compressed air required for a car tire at the required pressure within a specified time. Known compressor systems for breakdown kits are not designed for vehicle tires, such as those of a van or truck, which have a larger volume and / or a higher inflation pressure. The provided volume flow is too low to inflate such a vehicle tire in the specified time. The required long operating time would regularly lead to overheating of the compressor system, whereby the necessary inflation pressures cannot be achieved by known compressor systems.This is due to the fact that known compressor systems are made of plastics with the aim of achieving low weight and small size.

[0005] US 2020 / 0158099 A1 discloses such a compressor system made of plastic, wherein the air outlet end component of the cylinder, which is detachably connected to the outlet unit, has a metal insert to make this area resistant to the high pressures and temperatures prevailing there. Against this background, the object of the invention is to provide a compressor system for a breakdown assistance kit of the type mentioned above in a reliable and cost-effective design with a low weight and compact size, which enables a higher volume flow and a higher inflation pressure when filling vehicle tires.

[0006] This object is achieved with a compressor system according to the features of patent claim 1 and a breakdown assistance kit and method according to the independent claims. The subclaims relate to particularly useful developments of the invention.

[0007] According to the invention, a compressor system for a breakdown assistance kit is provided, comprising a motor, a piston which is driven by the motor via a crank mechanism and a one-piece cylinder main body having a pumping chamber in which the piston is mounted so as to be movable from a bottom dead center to a top dead center for compressing air, and a receiving chamber for receiving the compressed air compressed in the pumping chamber through an air outlet valve, wherein the cylinder main body is a plastic component, wherein the cylinder main body has a metal insert in the region of the air outlet valve.

[0008] It was advantageously recognized that a one-piece cylinder body, which forms the pumping chamber and the receiving chamber, is particularly reliable while maintaining a compact size and thus a low weight. The one-piece design of the area exposed to high pressure and high temperatures eliminates the need to connect and seal multiple components in this area. Due to the prevailing pressures and the resulting forces, plastic flanges must be large at the prevailing temperatures to ensure the most permanently tight connection possible.

[0009] The cylinder body features a metal insert in the area of ​​the air outlet valve, as it was recognized that this is where the highest temperatures are reached and where the flow velocity is high. This places a high thermal load on a plastic, along with high mechanical stress due to the high flow velocity and applied pressure. Conventional plastics cannot withstand these loads over the long term without damage. Conventional compressors designed for the required pressures and flow rates are made of metal and are therefore larger and significantly heavier.

[0010] According to the invention, it was recognized that a one-piece cylinder main body made of plastic is suitable for providing a lightweight compressor system that enables higher filling pressures than in known compressor systems of this type at a high volume flow rate if it has a metal insert in the particularly stressed area. The metal insert is preferably made of an iron alloy, a zinc alloy, or an aluminum alloy.

[0011] A one-piece cylinder main body is understood to mean that the cylinder main body does not consist of multiple components that form sealing surfaces with one another or that require disassembly during maintenance or repair. However, a one-piece cylinder main body consists of various materials, such as a plastic and a metal insert, and preferably glass fibers. Preferably, the metal insert is overmolded in the plastic of the cylinder main body. Alternatively, the metal insert can be permanently bonded to the plastic using other known means to form the one-piece cylinder main body.

[0012] A preferred embodiment provides that the plastic of at least the cylinder main body is a glass fiber-reinforced plastic, which preferably has a glass fiber content of 40% to 60%, and more preferably 45% to 50%, and is preferably a polyamide. Plastics with a glass fiber content of at least 40% and at most 60% are particularly suitable for use as the cylinder main body due to their high mechanical and thermal resilience. Polyamide, in particular, has proven to be a suitable plastic in this regard. Preferably, at least the other highly stressed components also have a similar glass fiber content.

[0013] A further preferred embodiment provides that the metal insert is positively enclosed by the plastic of the cylinder main body, and more preferably, extends with partial regions through the outer surfaces of the plastic of the cylinder main body. A positive enclosure of the metal insert by the plastic ensures a secure connection between the metal insert and the plastic, even under high thermal and mechanical stresses. Partial regions of the metal insert that protrude from the plastic of the cylinder main body into the surrounding area enable effective heat dissipation to the surrounding area. In particular, the partial regions can be designed as cooling fins and positioned in an area of ​​increased air circulation.

[0014] A further preferred embodiment provides for the air outlet valve to be a check valve, in particular a flutter valve. Check valves are reliable and cost-effective air outlet valves that have proven particularly suitable for medium gas exchange frequencies. Flapping valves are preferably used because they are particularly efficient, i.e., generate low backflow losses, and are lightweight. In particular, flutter valves enable effective gas exchange even at higher gas exchange frequencies.

[0015] A further preferred embodiment provides that the crank mechanism has gears, wherein the gears are made of metal at least in some areas, preferably exclusively. Plastic gears have a low durability given the high pressures to be generated at a high volume flow and the resulting high power to be transmitted, if they have the necessary compact design. It has proven advantageous to manufacture the particularly stressed areas, such as the teeth of the gears, from a metal, as this enables a compact design and long-term reliable operation. Gears made solely of metal have proven to be particularly durable and cost-effective. A further preferred embodiment provides that the pump chamber forms a dead space volume to limit a maximum pressure in the pump chamber, in particular a variable dead space volume that depends on the pressure in the pump chamber.Limiting the maximum pressure in the pumping chamber by means of a dead space volume enables a cost-effective and reliable limitation of the maximum pressure. This type of maximum pressure limitation is also more efficient at high pressures than releasing the compressed air via a relief valve. This reduces the temperature load in the pumping chamber, particularly under high thermal and mechanical loads that occur at high pressures. In operating conditions where pressure limitation is not necessary, the dead space volume reduces efficiency. Therefore, a dead space volume that is dependent on the pressure in the pumping chamber, i.e. that increases at high pressures, is preferred because this increases efficiency at lower pressures, resulting in less heating of the pumping chamber and thus a lower maximum temperature reached when filling a vehicle tire.A variable dead space can be created, for example, by a second, spring-loaded piston that is connected to the pump chamber parallel to the air outlet valve or by means of elastic side walls of the pump chamber.

[0016] A further preferred embodiment provides that the cylinder main body is suitable for providing a maximum pressure of at least 7 bar, preferably at least 8 bar, more preferably at least 9 bar and most preferably at least 10 bar, with temperatures of at least 150°C, preferably at least 170°C, more preferably at least 190°C, more preferably at least 220°C and most preferably at least 250°C being present in regions of the cylinder main body. A cylinder main body that is suitable for providing at least a maximum pressure of 7 bar at temperatures of at least 150°C enables a compressor system for breakdown kits that can generate higher filling pressures at high volume flows. If the cylinder main body is suitable for even higher pressures and temperatures, even higher filling pressures can be generated at high volume flows.Higher inflation pressures are understood to mean, in particular, an inflation pressure in the vehicle tire of at least 3 bar, preferably of at least 4 bar and more preferably of at least 5 bar.

[0017] According to the invention, a breakdown assistance kit comprising a compressor system according to the invention and a sealing device is provided, wherein the sealing device has a sealing means for sealing a vehicle tire, wherein the compressor system is preferably connectable to the sealing device. The breakdown assistance kit according to the invention enables the sealing and filling of a vehicle tire with a higher inflation pressure. The compressor system is particularly advantageous when used as a breakdown assistance kit, since breakdown assistance kits are lightweight and compact.

[0018] According to the invention, a method for sealing a vehicle tire using a compressor system according to the invention or a puncture kit according to the invention is provided, comprising at least the following steps: i) building up an overpressure by a piston in the compressor system, wherein the overpressure in the cylinder main body is at least 8 bar, preferably at least 9 bar and more preferably at least 10 bar, ii) conveying a sealing agent into a vehicle tire by means of the overpressure built up in the compressor system.

[0019] The method according to the invention for sealing a vehicle tire with a sealant is advantageous because, due to the high pressures that can be generated in the cylinder main body, vehicle tires can be filled and preferably sealed with higher pressures at a high volume flow.

[0020] The invention permits numerous embodiments. To further clarify its basic principle, one of them is shown in the drawing and is described below. This shows in

[0021] Fig. 1 shows a compressor system for a breakdown kit. Figure 1 shows a compressor system for a breakdown kit with a one-piece cylinder main body 1 that accommodates a piston 3 driven by a connecting rod 2 with an air inlet valve 4 within side walls 5 of a pumping chamber 6. The cylinder main body 1 accommodates an air outlet valve 7 that prevents the compressed air from flowing back from the receiving chamber 8.

[0022] If the motor 9 drives a second gear 11 via a first gear 10, the connecting rod 2 moves the piston 3 toward bottom dead center, so that air flows through the open air inlet valve 4 into the pump chamber 6 when the air outlet valve 7 is closed. After passing bottom dead center, the air in the pump chamber 6 is compressed when the air inlet valve 4 is closed and conveyed through the opening air outlet valve 7.

[0023] The air heated by the compression reaches its maximum temperature when it reaches top dead center, whereby the resulting flow causes the greatest thermal load on the cylinder main body 1 to occur in the area of ​​the narrowing pump chamber 6 in the direction of flow immediately upstream of the air outlet valve 7. In this area of ​​the pump chamber 6, the highest mechanical load also exists due to the pressure. In order to withstand this thermal and mechanical load, the cylinder main body 1, which is predominantly made of a glass fiber reinforced plastic, has a metal insert 12 in this area, which forms the surface of the cylinder main body 1 in the highly stressed area. The metal insert 12 is formed in one piece with the plastic of the cylinder main body 1 and is positively connected to it by an injection molding process.List of reference symbols Cylinder main body Connecting rod Piston Air intake valve Side walls Pumping chamber Air exhaust valve Receiving chamber Motor First gear Second gear Metal insert.

Claims

Patent claims 1. Compressor system for a breakdown assistance kit comprehensive - an engine (8), - a piston (3) driven by the motor (8) via a crank mechanism and - a one-piece cylinder main body (1) having a pumping chamber (6) in which the piston (3) is mounted so as to be movable from a bottom dead center to a top dead center for compressing air, and a receiving chamber (8) for receiving the compressed air compressed in the pumping chamber (6) through an air outlet valve (7), wherein the cylinder main body (1) is a plastic component, wherein the cylinder main body (1) has a metal insert (12) in the region of the air outlet valve (7).

2. Compressor system according to claim 1, characterized in that the plastic of at least the cylinder main body (1) is a glass fiber reinforced plastic, which preferably has a glass fiber content of 40% to 60% and more preferably of 45% to 50%, and is preferably a polyamide.

3. Compressor system according to claims 1 or 2, characterized in that the metal insert (12) is positively enclosed by the plastic of the cylinder main body (1) and preferably extends with partial areas through the outer surfaces of the plastic of the cylinder main body (1).

4. Compressor system according to one of the preceding claims, characterized in that the air outlet valve (7) is a check valve, in particular a flutter valve.

5. Compressor system according to one of the preceding claims, characterized in that the crank mechanism has gears (8, 9) which consist at least in partial areas, preferably exclusively, of metal.

6. Compressor system according to one of the preceding claims, characterized in that the pumping chamber (6) forms a dead space volume for limiting a maximum pressure in the pumping chamber (6), in particular a variable dead space volume dependent on the pressure in the pumping chamber (6).

7. Compressor system according to one of the preceding claims, characterized in that the cylinder main body (1) is suitable for providing a maximum pressure of at least 7 bar, preferably of at least 8 bar, more preferably of at least 9 bar and most preferably of at least 10 bar, wherein temperatures of at least 150 °C, preferably of at least 170 °C, more preferably of at least 190 °C, more preferably of at least 220 °C and most preferably of at least 250 °C are present in regions of the cylinder main body (1).

8. Breakdown assistance kit comprising a compressor system according to one of the preceding claims and a sealing device, wherein the sealing device has a sealing means for sealing a vehicle tire, wherein the compressor system is preferably connectable to the sealing device.

9. A method for sealing a vehicle tire using a compressor system according to one of claims 1 to 7 or a puncture kit according to claim 8, comprising at least the following steps: i) building up an overpressure by a piston (3) in the compressor system, wherein the overpressure in the cylinder main body (1) is at least 8 bar, preferably at least 9 bar and more preferably at least 10 bar, ii) conveying a sealing agent into a vehicle tire by means of the overpressure built up in the compressor system.

Images