GB2048641A

GB2048641A - Sensor

Info

Publication number: GB2048641A
Application number: GB8014868A
Authority: GB
Original assignee: VEB Kombinat Fortschritt Landmaschinen Neustadt (Bestand)
Current assignee: VEB Kombinat Fortschritt Landmaschinen Neustadt (Bestand)
Priority date: 1979-05-30
Filing date: 1980-05-02
Publication date: 1980-12-17
Also published as: PL121563B1; FR2457625A1; BG37531A1; HU181713B; CS227368B1; PL224566A1; SU1079197A1; GB2048641B; DE3013338A1; DD147183A3

Abstract

A sensor for use in the automatic control of an agricultural machine wherein a change in distance from a crop boundary or row of plants, is transmitted as a positional change to the solenoid plunger of an inductive transmitter comprises a housing (1) connectible to an agricultural machine and a rotatably journalled spring-loaded pin (2) with a crank pin (3), which is mounted at the front end of the pin (2) and which bears against a collar (13) of a spring-loaded, displaceable sleeve connected to a push rod (11) of the plunger. Mounted on the pin (2) opposite to the crank pin (3) is a lever arm (5) with a rotatably journalled and spring-loaded pin (6), to which are attached a feeler element (7), which is movable along a crop boundary or row of plants, and a stop (25). A stop (26) co-operable with the stop (25) is mounted on the lever arm (5) and a peg (14) projects from the pin (2) and into a recess of the housing (1). When a crop boundary 28 is sensed by movement of arm 7, this movement is transmitted to pin 2 as a rotational movement and as a result plunger 9 of the transmitter 10 is displaced by pin 3. <IMAGE>

Description

SPECIFICATION Sensor The present invention relates to a sensor for sensing the distance between an agricultural' machine and a plant row, especially maize.

Devices for sensing crop boundaries are disclosed in German (Dem. Rep.) patent specification Nos. 82 588 and 113684. Such a device consists of a housing comprising two central, spring-loaded rotary systems with or without clamping means for the springs.

The device is attached to a separate inductive transmitter. A disadvantage ofthis device is its large overall height and the cost and complication involved in sealing between the sensor element and the transmitter and in coupling them together without backlash.

In addition, devices are known which contain sensing elements, which are mounted on housings rotatable about stationary journals and also actuate stationary transmitters. Here again the coupling of sensor and transmitter is cómplicated and liable to failure. It is almost impossible to seal against rainwater and spray. The relatively large moment of inertia of the rotatable housing also mitigates against sensitive sensing. Once again there is a relatively large overall height, large volume and unfavourable mounting arrangements. As a result of this large height, these devices cannot be mounted at the divider points of harvesting machines, for example maize cutters and gatherers.

There is accordingly a need for a sensor which, inter alia, is suitable for mounting at the divider point of a harvesting machine and in which the coupling between sensor element and transmitter can be provided by a simple means without backlash and' minimum costs in sealing.

According to the present invention there is provided a sensor for sensing the distance between an agricultural' machine and a plant row, the sensor comprising a housing mountableon such' machine, an inductive transmitter arranged in the housing and comprising an induction coil plunger displaceable out of a rest position to control transmission by the transmitter, a drive member mounted in the housing to be angularly displaceable relative thereto through a limited range and comprising cam' means so operatively coupled to the plunger as to displace the plunger on displacement of the drive' member out of a rest position thereof, a lever arm connected to the drive member to be angularly displaceable therewith, a feeler element mounted on the lever arm to be angularly displaceable relative thereto out of a rest position on movement of the element in one direction against a stationary object and to displace the lever arm and thereby the drive member and plunger on movement of the element in the opposite direction against the object, and resilient means urging the plunger, drive' member and feeler element into their rest positions.

In one embodiment of the invention, the drive member comprises a pin, rotatable within a limited range, and having a crank pin at one end thereof, the pin being journalled in the housing. The range of movement of the pin is limited by a projection from the pin, for example a peg inserted into the pin, guided in a recess in the housing. The coupling between the plunger and the pin is provided by the crank pin bearing against a shoulder, for example a collar, of a spring-loaded, displaceable sleeve, connected to an extension rod of the plunger. To the opposite end of the pin there is attached the lever arm, on the free end of which is' mounted a spring-loaded spigot of the feeler element. The spigot is provided with a stop which co-operates with a stop on the lever arm.

Arranged in the housing is a torsion spring, which is anchored at one end to the housing and connected at its other end to an adjusting disc rotatably mounted on the pin. The spigot is firmly connected to a cover element covering a torsion spring which acts in a direction opposite to that of the spring in the housing and which is connected at one end to the cover element and at its other end to the lever arm.

The stop associated with the spigot is preferably located on the cover element.

The feeler elements, which is preferably formed as a straight or curved elongated' member, is clamped in a transverse bore in the spigot by a fixing screw extending axially in the spigot. The transverse bore in the spigot and the feeler element can have different cross-sectional shapes, for example quadrilateral or hexagonal.

An embodiment of the present invention will now be more particularly described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a longitudinal sectional view of a sensor according to the said embodiment; Fig. 2 is a plan view of the sensor; and Fig. 3 is a section of the sensor on the section line of Fig. 2.

Referring now to the drawings, there is shown a distance sensor comprising a pin 2, with a crank pin 3' mounted at one end thereof, rotatably journalled by means of a ball bearing 4 in a housing 1,the housing being connected to an agricultural' machine (not shown). Connected to the opposite end of the pin 2 is a lever arm 5, in which a spigot 6 carrying a feeler arm 7 is rotatably journalled by means of a ball bearing 8.

Also arranged in the housing lisa transmitter 10 having a solenoid plunger 9, which is connected by a push rod 11 to a spring-loaded sleeve 12. The sleeve has a flange or shoulder 13 pressurably bearing against the crank pin 3 under the bias of the spring. The range of movement of the pin 2 is limited by a peg 14, the axis of which intersects the axis of the pin 2 and the free end of which extends into a housing recess 15. The pin 2, together with the components secured thereto, is urged by a coil torsion spring 16 into a rest position in which the peg 14 bears against one end of the housing.The torsional force of the spring 16, which is located in an annular chamber 17 of the housing 1, is adjustable by virtue of the fact that one end 18 thereof is engaged in a bore 19 in the base of the chamber 17 and its other end 20 is engaged in a bore 21 in an adjusting disc 22. The disc 22 is mounted to be rotatable relative to the housing 1 and the pin 2 and is capable of being locked to the lever arm 5, the disc 22 forming a cover of the hous ing 1.

The spigot 6 is rotatably mounted on the lever arm 5 by means of a ball bearing 8, which is enclosed by a cap 23 secured to the spigot 6. The spigot, together with the feeler arm 7, is urged by a torsion spring 24 into a sensing position, which is also a rest position, in which a stop 25 on the cap 23 bears against a stop 26 on the lever arm 5. The spring 24 is engaged, with a degree of pretension, in a bore in the cap 23 and in a bore in the lever arm 5, the direction of bias of the spring 24 being opposite to that of the spring 16.

The arm 7 consists of a straight or curved bar and is firmly clamped in a transverse bore of the spigot 6 by means of a screw 27, extending axially of the spigot. The transverse bore which receives the arm 7, and the arm 7 itself, can be of different crosssections, for example quadrilateral or hexagonal.

In use when a crop boundary or row of plants 28 is sensed by movement of the feeler arm 7, this movement is transmitted via the cap 23, stops 25 and 26, and lever arm 5 to the pin 2 as a rotational movement. As a result, plunger 9 of the transmitter 10 is displaced by the crank pin 3 at the end of the pin 2, via the sleeve 12 and push rod 11. When the arm 7 is relieved of load, the pin 2 together with the lever arm 5 is rotated back by the spring 16 in the housing 1 and the spring-loaded sleeve 12 until the peg 14 in the pin 2 bears against the said one end of the recess 15. Thus the plunger 9 of the transmitter 10 is again displaced via the crank pin 3 and spring-loaded sleeve 12. For regulating the restoring force of the spring 16, the adjusting disc 22 is infinitely rotatable about the pin 2 and is locked to the lever arm 5 after adjustment.

When travelling backwards and on encountering an obstruction, the feeler arm 7 can be pivoted with the spigot 6 opposite to the direction of travel and against the bias of the spring 24. After the obstruction has been passed, the arm 7 is returned by the spring 24 to its rest position.

Such a sensor, with spring systems disposed alo nags'idle one another, has the advantage of a reduced overall height and thereby enables installation of the sensing device atthe divider head of a harvesting machine. A further advantage is that the transmitter and the means transmitting the feeler arm' movement are arranged in a common housing and thus there is no difficulty in the sealing of the individual parts of the housing, nor are additional coupling elements required between the transmitter and feeler arm. Yet another advantageous feature is the good sealing of the sensor device, as the cap 23 and the adjusting disc 22 serve to seal off the bearings, springs and components of the transmitter.

For the purpose of sensing a crop boundary or row of plants from the opposite side, the construction and rotational direction of the sensing device need to be arranged to be opposite, i.e. the same components can be employed but arranged to act in the opposite direction.

Claims

1. A sensor for sensing the distance between an agricultural' machine and a plant row, the sensor comprising a housing mountable on such'machine, an inductive transmitter arranged in the housing and comprising an induction coil plunger displaceable out of a rest position to control transmission by the transmitter, a drive member mounted in the housing to be angularly displaceable relative thereto through a limited range and comprising cam means so oper atively coupled to the plunger as to displace the plu nger on displacement of the drive member out of a rest position thereof, a lever arm connected to the drive member to be angularly displaceabletherew ith, a feeler element mounted on the lever arm to be angularly displaceable relative thereto out of a rest position on movement of the element in one direct ion against a stationary object and to displace the lever arm and thereby the drive member and plun ger on movement of the element in the opposite direction against the object, and resilient means urging the plunger, drive member and feeler element into their rest positions.

2. A sensor as claimed in claim 1, wherein the plunger is provided with an extension having an abutment engaged by the cam means

3. A sensor as claimed in claim 2, wherein the plunger extension comprises a rod and a sleeve mounted on the rod to be adjustable axially thereof, the abutment being provided by a collar on the sleeve.

4. A sensor as claimed in either claim 2 or claim 3, the resilient means comprising a respective spring acting on the extension to urge the plunger into its rest position.

5. A sensor as claimed in any one of the preceding claims, wherein the drive member comprises a pin' mounted to be rotatable about its axis.

6. A sensor as claimed in claim 5, the cam means comprising a projection extending from an end of the pin eccentrically of the pin axis.

7. A sensor as claimed in any one of the preceding claims, wherein the drive' member is provided with stop means co-operable with the housing to define the limits of displacement of the member.

8. A sensor as claimed in claim 7, the stop means comprising a projection projecting from the drive member into a recess of the housing, the length of the recess determining the range of angular displac ement ofthe drive member.

9. A sensor as claimed in any one of the preceding claims, the resilient means comprising a respective spring acting on the drive' member to urge it into its rest position.

10. A sensor as claimed in claim 3, wherein the spring acting on the drive member is a coil torsion spring.

11. A sensor as claimed in claim 10, wherein the spring is anchored at one end thereof to the housing and attached at its other end to adjusting means for adjusting the tension of the spring.

12. A sensor as claimed in claim 11, the adjusting means comprising an adjusting element rotatably mounted on the member, the adjusting element being locatable in a desired fixed position on the member.

13. A sensor as claimed in any one of the preceding claims, the cam means being provided at an end of the drive member and the lever arm being connected to the drive member at an end thereof opposite to the end with the cam means.

14. A sensor as claimed in any one ofthe preceding claims, wherein the feeler element comprises a spigot and is mounted on the lever arm by means of the spigot.

15. A sensor as claimed in claim 14, the resilient means comprising a respective spring acting on the spigot to urge the feeler element into its rest position.

16. A sensor as claimed in claim 15, wherein the feeler element comprises a cover element mounted on the spigot to cover the spring acting thereon.

17. A sensor as claimed in claim 16, wherein the spring acting on the spigot is connected atone end to the cover element and at its other end to the lever arm.

18. A sensor as claimed in any one of claims 14 to 17, wherein the feeler element comprises an elongate member secured to and projecting from the spigot.

19. A sensor as claimed in claim 18, wherein the elongate member extends into a transverse bore of the spigot and is clamped therein by threaded fastening means.

20. A sensor as claimed in claim 19, wherein the transverse bore is of non-circular cross-section.

21. A sensor as claimed in claim 20, wherein the transverse bore is of quadrilateral or hexagonal cross-section.

22. A sensor as claimed in any one of the preceding claims, wherein the drive member and feeler element are urged by the resilient means in mutually opposite rotational directions into their rest positions.

23. A sensor as claimed in any one of the preceding claims, wherein the feeler element and lever arm each comprise a respective abutment, the abutments being interengaged in the rest position of the feeler element.

24. A sensor as claimed in claim 23 when read with claim 16, wherein the abutment of the feeler element is provided on the cover element.

25. A sensor for sensing the distance between an agricultural' machine and a plant row, the sensor being substantially as hereinbefore described with reference to the accompanying drawings.