Return-Suction Filtration in a Self-Propelled Harvesting Machine
Hydraulic circuit without filtration
Simplified presentation of the hydraulic circuit incl. filter concept
With the return-suction filter, ARGO-HYTOS was the first filter manufacturer to launch a new, revolutionary filter system on the market.
Since then, this filter concept for mobile machines has become a standard in many applications, because it provides far-reaching functional improvements and lowers the system and maintenance costs.
Using the example of the harvester shown below, the reasons for the success of the return-suction filter concept can be illustrated.
The hydraulic system of such a beet harvester typically consists of:
Hydrostatic drive
(1) A variable pump in the closed circuit, connected to the hydraulic motor at the axles, ensures locomotion
Working hydraulics (2)
Fixed or variable pumps supply the users in the open or closed circuit
Steering system (3)
A variable pump in the open circuit supplies the steering system
Filter selection
Filters in the hydraulic circuit guarantee function and / or wear protection. Thus one differentiates between protective filters (function protection = coarse hydraulic filters / strainers) and working filters (wear protection = fine hydraulic filters).
What concerns the drive, protecting the filling pump and / or the hydrostat as well as ensuring the oil cleanliness and thus the wear protection are of primary importance. Here a working filter is required.
The same applies for the working hydraulics (open / closed circuit), because also here the pump has to be protected and the necessary oil cleanliness has to be ensured.
The main focus with steering systems mostly lies on the function protection of the steering unit and is implemented by a protective filter.
If necessary, more than two plates can be stacked, to save e.g. a collector – as decided upon in this example. The adjacent picture shows the return-suction filter with three connecting plates. All lines could be guided and directly connected to the filter. Just as uncomplicated, a housing ventilation was integrated in the filter cover.
This example shows how and how quickly, based on existing technical solutions, trendsetting products arise with the relevant application know-how and intelligent concepts.
A single return-suction filter (4) takes over almost all the tasks mentioned above. The filter concept for the entire machine is completed by two more filters from the ARGO-HYTOS portfolio:
Ventilating filter with filling filter (5)
For ventilation of the hydraulic tank. The filling strainer downstream of the ventilating filter prevents coarse dirt from entering the tank while filling or with re-filling of oil due to maintenance or repair work.
Suction filter (6)
The working hydraulics have - at the suction side – not been connected to the return-suction filter, but suck oilfrom the tank via a separate and maintenance-free suction filter.
Explanation: In order to maintain the pre-charge pressure of approx. 0.5 bar at the connection of the filling pump,a minimum surplus between return and suction volume is necessary under all operating conditions.
Production launch
Since all ARGO-HYTOS filters are developed and manufactured by the company itself, the users can be provided with a lot of information such as e.g. pressure loss characteristics at an early stage. Thus, the suitable version was selected from the catalogue series E 598 / E 998 and installed into a harvester.
This was followed by extensive testing under real conditions. After successful completion of these tests, the preparations for the production launch could be started. To make the new return-suction filter even more advantageous, in our example, a customized filter on the basis of the catalog part was generated for the machine manufacturer.
The series E 598 / E 998 features a very high modular connection concept with two stackable connecting plates. For the return and suction side, two connecting plate variants are already available in the standard, which can be positioned turned through 90° to each other. Thus, a variety of connection configurations are possible.
Customer benefit
- Improved cold start characteristics of the system, as the filling pump is supplied with pre-charged oil (prevention of cavitation)
- Fewer components by saving a filter
- Reduction of spare parts and maintenance costs
All the more pleasing, when in addition to the technical improvements, the customer benefit is significantly increased also by reducing the system costs.