In general, small hydraulic excavators mount the fan on the engine, with the water radiator and oil cooler arranged front-to-back (i.e., in a series structure), as shown in Figure 1. This structure is easy to manufacture but prone to clogging and overheating, and is difficult to arrange; when a suction fan is used, the engine offers relatively high resistance to the fan airflow. The improvement approach is to change from series to parallel. The water radiator and oil cooler are made into a single unit, as shown in Figure 2. The overall dimensions of the radiator assembly are slightly larger than the original, and the matching between the radiator and the fan is more reasonable.
As for the oil cooler, being closer to the fan, the airflow passing through its cooling core provides more thorough and uniform cooling. From the perspective of heat conduction, the heat generated by the hydraulic system is radiated into the air through the cooling core and then carried away by the cold air produced by the high-speed rotating engine fan. With the system heat dissipation unchanged, more thorough and uniform cold air will inevitably carry away more heat, thereby improving the heat dissipation capacity of the radiator.
To reduce costs, aluminum is selected as the manufacturing material for the parallel integrated radiator. In terms of the overall heat dissipation effect of the product, for the same machine model and the same frontal area, an aluminum radiator has higher heat dissipation efficiency than a copper radiator.
Due to the particular working environment of excavators, large amounts of dust, debris, lint, and insects are drawn into the radiator core. During maintenance and cleaning of the radiator, this fin structure only allows dust to be washed away, while debris, lint, and insects all become stuck in the dense small holes on the fins, making cleaning very difficult or even incomplete. Over time, this clogs the radiator core and reduces heat dissipation capacity. To solve the problem of the water radiator core fins being prone to clogging and to facilitate maintenance and cleaning, an improvement plan was proposed to change the fin structure and eliminate the louvers on the fins while ensuring heat dissipation capacity.
The specific improvement plan is as follows: eliminate the louvers on the fins (see Figure 3) and stamp the fins into a wavy shape (corrugated fins), as shown in Figure 4. When airflow passes through the radiator core, the corrugations and protrusions on the fins create turbulence in the airflow, making the radiator less prone to clogging and preventing debris, lint, and insects from all becoming stuck on the fins. Without louvers, the fins have a larger heat dissipation area. At the same time, compared with louvered fins, wavy fins are easier to process, and manufacturing costs decrease accordingly.
After installation and testing comparison, under the same working conditions, the test data show that the cooling capacity of the improved cooling system has been significantly improved. In addition, because the wind resistance of the entire cooling system is reduced, the noise generated by the original fan is also relatively reduced by 1.5 dB. With the improved radiator, each machine can save 350 yuan in cost.
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