Crop Machine with an Electronically Controlled Hydraulic Cylinder Flotation System

Abstract

In a crop harvesting machine there is provided a pair of hydraulic float cylinders for a header relative to a vehicle, where a float pressure to the cylinders is directly controlled by an electronic control supplying a variable control signal to a PPRR valve arrangement to maintain the float pressure at a predetermined value. At the set pressure a predetermined lifting force is provided to the header. A position sensor is used to generate an indication of movement and/or acceleration. The electronic control is arranged, in response to changes in the sensor signal, to temporarily change the control signal to vary the lifting force and thus change the dynamic response of the hydraulic float cylinder. In order to reduce static friction so that the system can react quickly, an arrangement is provided for causing relative reciprocating movement in an alternating wave pattern between the piston and cylinder.

Description

[0001]This application is a divisional application of application Ser. No. 15 / 188,468 filed Jun. 21, 2016.[0002]This invention relates to crop machine with an electronically controlled hydraulic cylinder flotation system of the header on support tractor. In particular the arrangement provides firstly a construction in which the effect of static friction provided by cylinder seals is significantly reduced so as to reduce resistance to motion of the cylinder in the floating action. Secondly the arrangement herein provides a dynamic control system which modifies the forces applied by the cylinder in response to movement of the header relative to the tractor. The present invention can be used in many different engaging systems such as hay tools, rakes, pickups, etc but is particularly applicable both for swathers or windrowers where the header is carried on a swather tractor and for combine harvesters where the header is carried by a combine adapter connected to the feeder house. If use...

AI Technical Summary

Benefits of technology

[0052]In this way the control system can be used to increase the lifting force dynamically during the time that the header is being lifted by contact with the ground or another obstacle so as to improve the response to forces from ground contact. In addition as soon as the ground contact is removed thus halting any further acceleration, the lifting force can be significantly reduced so that the weight of the header is re-applied in the downward direction thus damping any further upward floating movement. This avoids or reduces the situation where the header is lifted by ground force or engagement with an obstacle and then remains lifted for an extended period of time thus interfering with the cutting of the crop while the header remains raised.

[0053]It will be appreciated that the dynamic control of the lifting forces depending upon the movement of the header can be used both in a ground flotation mode and also when cutting at a set raised height. In the latter condition, float action is typically provided in order to float ...

Problems solved by technology

However, due to internal friction of the cylinder seals of the flotation cylinders, these systems typically have poor ground following capabilities unless the mass supported by the ground is significant, in the order of 15% of the header mass.

With this level of ground pressure (mass of header carried by the ground), wear on the ground contacting components is significant.

Also, when hitting an obstacle, a higher ground pressure is und...

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