Lubricant for construction machinery

Abstract

The present invention relates to a lubricant for a construction machine (100), wherein the lubricant is a lubricating grease comprising a base oil and a thickener, wherein the lubricant has a walking penetration according to DIN 2137 of 265 to 430 [0.1mm].

Description

[0001] The present invention relates to lubricants for construction machinery, in particular, but not exclusively, compaction devices with an electric motor. A further aspect of the present invention relates to a construction machine, in particular compaction devices such as rammers and vibratory plates, equipped with the novel lubricant. Background of the invention

[0002] Rammers and vibrators, also known as compaction devices, are construction machines used to compact soil, asphalt, and other materials. They are used to ensure that the subsoil is stable and load-bearing, which is particularly important for foundations, paths, and roads.

[0003] Vibratory plates, also often called vibratory compactors, compact the subsoil through vibrating movements. They have a flat, heavy base plate that is set in motion by vibrations. Vibratory plates require more space than rammers, but are therefore suitable for larger, flatter areas. They work well on non-cohesive soils such as sand or gravel.

[0004] Rammers, also known as vibratory rammers, work by repeatedly striking the ground vertically. They have a compact design and are mostly used in confined or difficult-to-access areas. Powerful, pulsating movements compact the soil to a greater depth. Rammers are primarily used on cohesive soils (e.g., loam, clay) that require more energy to compact.

[0005] Vibratory rammers for subsoil compaction, for example, are based on a multi-spring vibration system within the device, in which a gearbox converts the rotating motion of its combustion or electric motor into an up-and-down movement. This causes the base plate to lift several centimeters off the subsoil at a high frequency, compacting it upon re-entry.

[0006] Proper lubrication is essential for the operation of construction equipment such as rammers and vibratory plates. Choosing the right lubricant and performing regular maintenance play a crucial role in preventing breakdowns and maximizing machine lifespan. Specific challenges such as vibration, dirt ingress, and extreme temperatures necessitate a tailored lubrication strategy.

[0007] Machines like rammers and vibratory plates are subjected to extreme vibrations. These vibrations can cause lubricant loss or uneven distribution. Furthermore, they often operate in dirty environments (e.g., on construction sites) where dust and dirt can penetrate the gearboxes. If dirt particles accumulate in the lubricant, this can impair lubrication and lead to increased wear. Additionally, the numerous moving parts within a rammer (pistons, springs, connecting rods, gears) or within a vibratory plate compactor (e.g., eccentrics in an oil bath) can cause significant churning losses.

[0008] Particularly in rammers, grease can be pumped into areas where there is no tribological stress. This can cause critical tribological systems to either run dry or lubricant to accumulate at the base of the machine, where it cannot be displaced. This can lead to damage to the components (plastic deformation or breakage) during a stroke.

[0009] Based on the aforementioned problem, an object of the present invention is to provide a lubricant for construction machinery that generates low power losses and is robust with regard to leakage / dust ingress in harsh construction site environments. Finally, a construction machine equipped with the novel lubricant is to be provided that is maintenance-free with respect to the lubricant.

[0010] The problem is solved by the subject matter of the independent claims. Advantageous embodiments relating to the subject matter of the independent claims are found in the dependent claims.

[0011] Accordingly, the present invention relates to a lubricant for a construction machine, wherein the lubricant is a grease comprising a base oil and a thickener, and wherein the lubricant has a working penetration according to DIN 2137 of 265 to 430 [0.1 mm]. The classification according to NLGI described in DIN 51 818 ranges from very soft (class 000) to very hard (class 6). The grease according to the invention thus has an NLGI class between 2 and 00. The lubricant of the present invention is therefore a grease, not a lubricating oil. This has the advantage that the three-dimensional network structure formed by the thickener absorbs the base oil in a sponge-like manner (a colloidal suspension is formed) and releases it to the friction surfaces of the construction machine over a definable period of time. In this respect, the teaching of the present invention counters a technical prejudice regarding construction machines, such as rammers or similar equipment.Vibratory plates. To ensure adequate lubrication, these are currently exclusively lubricated with oil. However, oil lubrication often results in high splashing losses. Furthermore, a reliable seal against foreign matter from the environment must be guaranteed. The inventive flexural penetration of the lubricant ensures that sufficient oil oozes from the thickener's network structure at all times, thus lubricating the moving parts of the construction machine. Simultaneously, excessive splashing losses are prevented by the controlled release of the base oil. The inventive grease also provides a seal against foreign particles such as construction dust without the need for additional sealants.

[0012] According to another embodiment, the base oil has a viscosity of 22 to 220 mm² / s at 40°C. Preferably, the viscosity of the base oil can be 34–64 mm² / s at 40°C.

[0013] According to another embodiment, the base oil comprises a mineral oil, polyalphaolefin, polyglycol, ester or combinations thereof.

[0014] According to another embodiment, the thickener comprises a calcium complex, an aluminum complex, a barium complex, a sodium complex, a lithium complex, polyurea, lithium, lithium calcium, bentonite, amorphous silicon dioxide, or combinations thereof. Such thickeners exhibit a particularly advantageous network structure to optimally control the aforementioned leaching of the base oil over a defined period within a relevant temperature range typical for construction machinery.

[0015] According to another embodiment, the lubricant has a scuffing load-bearing capacity according to DIN ISO 14635-3 of damage force level 10 or higher.

[0016] Another aspect of the present invention relates to a construction machine, in particular a rammer or vibrator, wherein the construction machine comprises the following: a motor; a compressor plate; at least one housing which is arranged between the motor and the compressor plate and has at least one kinematic mechanism, wherein a lubricant mentioned above is provided in the housing to lubricate the kinematic mechanism.

[0017] In the case of a rammer, the housing can be a volume containing a gearbox and a percussion mechanism connected to the gearbox. The lubricant is provided within the housing in such a way that it lubricates the tribological contacts in both the gearbox and the percussion mechanism. In the case of a vibrator, a gearbox housing can accommodate the gearbox, and a separate eccentric housing can accommodate an eccentric for generating imbalances. The lubricant is preferably provided in both housings. The lubricant can, for example, be applied to the inner wall of the respective housings.

[0018] According to another embodiment, the construction machine has a gearbox which is arranged between the motor and the compressor plate, wherein the gearbox is lubricated with the lubricant.

[0019] In another embodiment, the motor is an electric motor. The construction machine is preferably battery-powered. It has been found that the lubricant according to the invention offers significant advantages, particularly with battery-powered construction machines. By reducing splashing losses, the mechanical efficiency of the construction machines is increased, resulting in longer operating times before a battery replacement is necessary.

[0020] In a further embodiment, the gearbox housing defines an interior space in which the amount of lubricant is less than 60 vol%, preferably less than 15 vol%, and particularly preferably between 5 and 10 vol% of the free interior space. Such an amount of lubricant ensures that the tribological contacts are adequately lubricated while simultaneously reducing splashing losses.

[0021] In a further embodiment, the gearbox is housed in a gearbox casing, with the lubricant being applied to the inner walls of the gearbox casing. The lubricant, which is a grease lubricant, is arranged on the inner walls of the gearbox casing in such a way that the three-dimensional network structure of the thickener is spaced apart from the tribocontacts. In other words, only the base oil seeping out wets the tribocontacts during operation.

[0022] Further advantages arise from the following description of the figures. The figures, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0023] They show: Fig. 1 a schematic representation of a rammer; Fig. 2 schematic diagram regarding the mechanical efficiency of a rammer as a function of the engine speed and type of lubrication. Detailed description

[0024] The Figure 1 Figure 1 shows a schematic representation of a rammer. The rammer 100 according to Figure 1 is an electric rammer, i.e., the rammer is equipped with an electric motor 102. The electric motor 102 is located in the Figure 1In the illustrated embodiment, the electric motor is arranged on the outside of a gearbox housing 106. However, it is also conceivable to arrange the electric motor inside the gearbox housing.

[0025] One in Figure 1 The schematically depicted motor shaft 108 connects the motor to a gearbox 104. The gearbox 104 is in Figure 1 This is shown only schematically. It can include the transmission elements customary in the prior art, which convert a rotational movement of the electric motor 102 into a linear movement of a drive rod 110. In particular, the rotational movement of the motor shaft 102 is converted by the gearbox 104 into an oscillating movement of the drive rod 110.

[0026] The drive rod is connected to a piston rod 112. A piston 114 is arranged at one end of the piston rod 112 opposite the drive rod 110. The piston 114 is part of a stamping mechanism that connects the gearbox 104 to a base plate 120. The piston 114 is linearly movable within a base 118. The stroke movement of the piston 114, introduced via the drive rod 110, can be transmitted to the base 118 via spring elements 116. The piston 114, movably arranged in the base with the spring elements 116, forms a spring-mass oscillator for exciting the base plate 120.

[0027] The base plate 120 is located at one end of the foot section 118, opposite the gearbox 104. During operation, the base plate 120 is in contact with the substrate to compact it. For this purpose, the reciprocating movement of the piston 114 is transmitted to the base plate 120 via the spring elements 116.

[0028] The rammer 100 also has a handle 122, which is connected to the gearbox housing 106. The handle 122 can be used by the user to guide the rammer 100 across the ground.

[0029] All mechanical transmission elements of the rammer 100 are subject to heavy stress, as they are continuously moved at high frequency. To ensure long service life and adequate cooling of the friction surfaces, it is known to provide lubricants inside the rammer, for example, inside the gearbox housing 106.

[0030] According to the present invention, a lubricating grease with a working penetration of 265 to 430 [0.1 mm] according to DIN 2137 is used to lubricate the rammer. The lubricating grease is applied, in particular, to an inner wall of the gearbox housing 106. The thickening components contained in the lubricating grease form a structure of microscopic particles or filaments. This thickener structure forms a network in which the base oil is retained. Since the lubricating grease has the claimed working penetration, it oozes out of the thickener structure at the desired rate in combination with the claimed base oil viscosity, thereby ensuring advantageous lubrication of the gearbox contacts and sliding systems of the rammer 100.In other words, the base oil bleeds out of the thickener structure quickly enough to adequately lubricate the rammer's tribological contacts, while simultaneously ensuring that only the necessary amount of base oil bleeds out. This significantly reduces splashing losses.

[0031] For example, consider the Figure 2Reference is made to a figure showing the mechanical efficiency of a rammer as a function of motor speed and lubrication type. It is immediately apparent that the mechanical efficiency of rammers can be significantly increased by the grease lubrication according to the invention. This becomes increasingly evident, particularly at high motor speeds, e.g., above 2,000 rpm. Very high speeds are achieved, especially in combination with electrically operated rammers. In one example, the rammer reaches speeds of approximately 20,000 rpm. Similarly high speeds are also achieved with electrically operated vibrators. Such high speeds, in combination with the grease lubrication according to the invention, lead to particularly high mechanical efficiencies, as is the case with a rammer in Fig. 2 shown.

[0032] The present invention is not limited to the invention described in Figure 1The application of the lubricant according to the invention is limited to the illustrated rammer 100. Rather, it can also be used profitably in many other construction machines. For example, the use of the lubricant according to the invention in vibratory plates (vibrators) or demolition hammers is also conceivable. Reference symbol list

[0033] 100 Rammer 102 Motor 104 Gearbox 106 Gearbox housing 108 Motor shaft 110 Drive rod 112 Piston rod 114 Piston 116 Spring element 118 Foot 120 Base plate 122 Handle

Claims

1. Lubricant for a construction machine (100), wherein the lubricant is a grease comprising a base oil and a thickener, wherein the lubricant has a walking penetration according to DIN 2137 of 265 to 430 [0.1mm].

2. Lubricant according to claim 1, wherein the base oil has a viscosity of 22 to 220 mm. 2 / s at 40°C, preferably 34 to 64 mm 2 / s at 40°C, exhibits.

3. Lubricant according to claim 1 or 2, wherein the base oil comprises a mineral oil, polyalphaolefin, polyglycol, ester or combinations thereof.

4. Lubricant according to any one of claims 1 to 3, wherein the thickener comprises a Ca complex, Al complex, Ba complex, Na complex, Li complex, polyurea, Li, LiCa, bentonite, amorphous silicon dioxide or combinations thereof.

5. Lubricant according to any one of claims 1 to 4, wherein the lubricant comprises: - 65 - 97% base oil; - 3 - 30% thickener; - 0 - 10% additives.

6. Lubricant according to any one of claims 1 to 5, wherein the lubricant has a scuffing load-bearing capacity according to DIN ISO 14635-3 of damage force level 10 or higher.

7. Lubricant according to any one of claims 1 to 6, wherein the lubricant contains solid lubricants, in particular PTFE, ZnS, SnS2, graphite, Ca2P2O7, and / or MoS2.

8. Construction machine (100), in particular rammer or vibrator, wherein the construction machine (100) comprises: - a motor (102); - a base plate (120); - at least one housing which is arranged between the motor and the compaction plate and has at least one kinematic mechanism, wherein a lubricant according to one of claims 1 to 7 is provided in the housing to lubricate the kinematic mechanism.

9. Construction machine (100) according to claim 8, wherein the construction machine has a gearbox which is arranged between the motor and the compressor plate, and wherein the gearbox is lubricated with the lubricant.

10. Construction machine (100) according to claim 8 or 9, wherein the motor (102) is an electric motor, and wherein the electric motor is preferably operated at a speed between 18,000 rpm and 22,000 rpm during normal operation.

11. Construction machine (100) according to claim 10, wherein the motor (102) of the construction machine (100) is battery-operated.

12. Construction machine (100) according to one of claims 8 to 11, wherein the gearbox (104) is accommodated in a gearbox housing (106) and the lubricant is provided on inner walls of the gearbox housing (106).

13. Construction machine (100) according to claim 12, wherein the gearbox housing defines an interior space, and wherein the amount of lubricant is less than 60 vol-%, preferably less than 15 vol-%, particularly preferably between 5 and 10 vol-%, of the free interior space.

14. Construction machine (100) according to one of claims 8 to 13, wherein a tamping unit is arranged between the gearbox and the base plate and wherein the tamping unit is lubricated by the lubricant.

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