Mechanical gearbox with sintered gears, geared motor and food processing machine with gearbox or geared motor

Abstract

Mechanical transmission (4), comprising a transmission housing (6) and meshing gears (7), characterized in that the transmission housing (6) is made of stainless steel, in particular stainless steel, and that at least one gear (7) meshing with another gear (7) is sintered and has open sinter pores on the surfaces of the gear (7) and a lubricant in the sinter pores.

Description

[0001] The invention relates to a mechanical gear for the food industry with sintered gears having the features of the preamble of claim 1, a geared motor with the gear and a food processing or food handling machine with the gear or the geared motor.

[0002] Easy-to-clean stainless steel gears are state-of-the-art in the food industry. These gears are usually lubricated with an artificial, food-safe grease that is harmless to health. It is also state-of-the-art, as numerous studies by food inspectors have shown, that food products are contaminated with mineral oils, for example, from drive components.

[0003] The object of the invention is to propose a gear unit for food processing which has the properties of an easy-to-clean stainless steel gear unit and at the same time prevents or at least significantly reduces the risk of escaping grease.

[0004] This object is achieved according to the invention by the features of claim 1.

[0005] The mechanical transmission according to the invention with the features of claim 1 comprises a transmission housing made of a rust-proof material, for example, stainless steel, and sintered gears arranged in the transmission housing and meshing with each other. Due to their production by sintering, the sintered gears have pores, referred to here as sintering pores, which can be filled with lubricant, similar to how a sponge can absorb water. The transmission can, for example, comprise a planetary gear (epicyclic gear), in which planetary gears (epicyclic gears) are made of the sintered material, while the remaining gears are made of standard hardened steel. When the gears come into contact, the sintered gears release lubricant, which reduces friction. After tooth contact, the sintered gears absorb the lubricant again, so that the lubricant, although liquid, always remains bound.Any other gears, such as spur gears and bevel gears, can also be manufactured using this technology. At least one of two or more meshing gears is always sintered and contains the lubricant in its open sintered pores on the gear surfaces.

[0006] According to the invention, the gear housing comprises or consists of a stainless steel. The steel can also be a stainless cast steel. The gear with the stainless steel gear housing has the advantage of safe use in the food industry, although the invention is not limited to use in the food industry. Gearboxes with sintered gears are particularly well suited for drives made of stainless steel. Due to the use of stainless steel, which has poor thermal conductivity, the drives must be designed larger than normally necessary for better cooling. This leads to high transmittable torques of the gears. In most applications, these high transmittable torques are not required. A reduction in the transmittable torques due to sintered gears does not have a negative impact on the application.

[0007] The gears of the transmission according to the invention have open sintered pores on the surfaces of the gears, which, according to the invention, contain a lubricant, in particular a lubricating grease or lubricating oil. Sintered pores are small cavities in the gears created by sintering during the production of the gears, with sintered pores near the surface on the surfaces of the gears, for example, on tooth flanks, tooth sides, tooth tips, and on the end faces of the gears, being open. Because the sintered pores of the gears contain the lubricant, the gears have a lubricant reservoir and self-lubrication. Self-lubrication reduces friction and wear of the gears during operation compared to unlubricated gears.

[0008] An advantage of the invention is the possibility of operating the gear unit without any lubricant other than the lubricant in or out of the sintered pores in the gear housing. This eliminates the risk of lubricant leakage from the gear housing, making the gear unit according to the invention safe to use in the food industry. The invention does not preclude the use of an edible oil or edible fat as a lubricant instead of, for example, a technical oil or grease, or lubricating oil or grease.

[0009] The dependent claims relate to advantageous embodiments and further developments of the invention.

[0010] In particular, the gear housing is made of stainless steel with the material number 1.4301 or 1.4404, or is made of such a material, or a similar stainless steel used in the food industry. These stainless steels are rust-proof and acid-resistant, austenitic chromium-nickel steels, which are safe for use in the pharmaceutical and food industries.

[0011] One embodiment of the invention provides for an increase in corrosion resistance of the gear housing by electropolishing.

[0012] Another subject of the invention is a geared motor with a gearbox of the type explained above. A geared motor has an electric motor and a gearbox driven by the electric motor, which is, for example, flanged to the electric motor or accommodated in a motor housing of the electric motor, wherein in the latter case the motor housing is also the gearbox housing.

[0013] The invention also further relates to a food processing machine with a drive having the gear unit according to the invention or the geared motor according to the invention. A food processing machine is understood to mean a machine or, for example, a system in or with which food is processed, in particular agricultural products or animal products are prepared, processed, or treated for human consumption. A food processing machine can, for example, comprise or be a kneading, stirring, comminuting, dosing, or mixing device, machine, device, or system. The list is exemplary and not exhaustive.

[0014] All features mentioned in the description and / or illustrated in the drawings can be implemented individually or in any combination in embodiments of the invention. Embodiments of the invention that include only a portion of the features of a claim, including the independent claim, are possible.

[0015] The invention is explained in more detail below using an exemplary embodiment illustrated in the drawing. The sole figure shows a schematic representation of an exemplary embodiment of the invention.

[0016] As an exemplary embodiment of the invention, a mixer 8 for food is shown in the drawing, which can generally also be understood as a food processing or food preparation machine 1 or as part of a food processing or food preparation machine 1. Instead of the mixer 8, a chopper, a dosing device, or another device, system, machine, or the like for processing or handling food (not shown) can also be used. This list is exemplary and not exhaustive.

[0017] The food processing or handling machine 1 according to the invention has a drive with a geared motor 2 according to the invention, which has an electric motor 3 and a gear 4 according to the invention, via which it drives the food processing or handling machine 1. Instead of the electric motor 3, the geared motor 2 can also have, for example, a hydraulic or pneumatic motor (not shown).

[0018] The electric motor 3, or generally the motor of the geared motor 2, has a motor housing 5, and the gear 4 has a gear housing 6, which in the exemplary embodiment is flange-mounted to the motor housing 5, i.e., is screwed to the motor housing 5. It is also possible, for example, for the geared motor 2 to have a common housing for its motor and the gear 4 (not shown).

[0019] The motor housing 5 and the gear housing 6, or the common housing of the geared motor 2, are made of stainless steel, in the exemplary embodiment, of stainless steel with the material number 1.4301 or 1.4404. The corrosion resistance of the steel of the motor housing 5 and the gear housing 6, or the common housing of the geared motor 2, can be increased by electropolishing. A stainless cast steel is also possible for the motor housing 5 and the gear housing 6, or the common housing of the geared motor 2.

[0020] The gear 4 according to the invention is a mechanical gear 4—in the exemplary embodiment, a planetary gear (epicyclic gear)—with intermeshing, sintered gears 7, i.e., gears produced by sintering. The gears 7, or at least at least one gear 7 meshing with another gear 7, has sintered pores, with sintered pores near the surface on the surfaces of the gear 7 being open. It is sufficient if a gear 7 meshing with another gear 7 is sintered and has the sintered pores. For example, planetary gears (epicyclic gears) 9 of the planetary gear are sintered. The other gears 7 can be sintered or unsintered, but can be gears 7 made of stainless steel, for example. According to the invention, the sintered pores open on the surfaces of the gear 7 contain a lubricating oil, a lubricating grease, or a lubricant in general, whereby an edible oil or edible fat can also be contained in the sintered pores as a lubricant.The lubricant can be introduced under pressure into the sintered pores of the gear(s) 7. In this way, the sintered gears 7 of the transmission 4 according to the invention contain a lubricant reservoir for self-lubrication. The transmission housing 6 is preferably "dry" on the inside, meaning it contains no lubricant other than the lubricant in the sintered pores of its gears 7. This prevents lubricant from escaping from the transmission 4, even if the transmission housing 6 is leaking.

Claims

[1] Mechanical transmission (4), with a transmission housing (6) and with meshing gears (7), characterized by that the gear housing (6) comprises a stainless steel, in particular consists of the stainless steel, and that at least one gear (7) meshing with another gear (7) is sintered and has open sintering pores on surfaces of the gear (7) and a lubricant in the sintering pores. [2] Transmission according to claim 1, characterized by that the gear housing (6) is made of stainless steel with the material number 1.4301 or 1.4404. [3] Transmission according to claim 1 or 2, characterized by that the corrosion resistance of the steel of the gear housing (6) is increased by electropolishing. [4] Transmission according to one or more of claims 1 to 3, characterized by that the gear (4) has a planetary gear. [5] Geared motor, characterized bythat the geared motor (2) has a gear (4) according to one or more of the preceding claims. [6] Food processing or food processing machine (1) with a drive with a gear (4) according to one or more of claims 1 to 4 or with a drive with a gear motor (2) according to claim 5.

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