Force sensor, in particular suitable for an electrohydraulic hitch control system of an agricultural tractor

Patent metadata

Field	Value
Publication number	US-11073432-B2
Application number	US-201715674243-A
Country	US
Kind code	B2
Filing date	Aug 10, 2017
Priority date	Aug 12, 2016
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

A force sensor is suitable for an electrohydraulic hitch control system of an agricultural tractor. The force sensor has an outer cylindrical part with a bore and a measuring rod fixed on one side in the bore. A central section of the cylindrical part is provided as force introduction section. Two outer sections of the cylinder part are removed equally far axially from the center of the force introduction section and are provided as abutment sections. The measuring rod is clamped in an area of the force introduction section.

First claim

What is claimed is:

1. A force sensor, comprising:
an outer cylindrical part with a bore and a measuring rod fixed on one side in the bore; wherein:
a central section of the cylindrical part is a force introduction section,
two outer sections of the outer cylindrical part are abutment sections, the two outer sections are removed equally far axially from the center of the force introduction section, and
the measuring rod is clamped in the outer cylindrical part at an axial location of the force introduction section.

2. The force sensor according to claim 1 , wherein the outer cylindrical part includes:
a first conical section extending from the force introduction section in a first axial direction, the first conical section having decreasing wall material thickness in the first axial direction;
a second conical section extending from the force introduction section in a second opposite axial direction, the second conical section having decreasing wall material thickness in the second axial direction;
a first cone-shaped transition extending from the first conical section toward a first one of the abutment sections, the first cone-shaped transition having increasing wall material thickness in the first axial direction; and
a second cone-shaped transition extending from the second conical section toward a second one of the abutment sections, the second cone-shaped transition having increasing wall material thickness in the second axial direction,
wherein the first and second conical sections each extend over an axial length that is longer than an axial length over which the corresponding first or second cone-shaped transition extends.

3. The force sensor according to claim 2 , wherein a ratio of the axial length of the first and second conical sections to the axial length of the respective first or second cone-shaped transition is at least 4:1.

4. The force sensor according to claim 3 , wherein
a change in material thickness extends continuously at at least one of: a transition between the force introduction section and the first and second conical sections; a transition between the first and second conical sections and the corresponding first or second cone-shaped transition; and a transition between the first and second cone-shaped transitions and the corresponding abutment section.

5. The force sensor according to claim 4 , wherein the measuring rod has a conical shape in a section from a clamped region toward a non-clamped end.

6. The force sensor according to claim 5 , wherein the measuring rod has at least two flattened shoulders configured for engagement by a screw-in tool.

7. The force sensor according to claim 4 , further comprising:
a permanent magnet fixed to a non-clamped end of the measuring rod; and
a Hall sensor inserted into a receiving section of the cylindrical part, the Hall sensor configured to detect a position change of the permanent magnet in relation to a plane radial to a longitudinal axis of the outer cylindrical part.

8. The force sensor according to claim 7 , further comprising:
a circuit board accommodated in the receiving section of the outer cylindrical part, the circuit board having evaluation electronics for the Hall sensor.

9. The force sensor according to claim 8 , wherein the evaluation electronics on the circuit board are configured to convert a sensor signal into an analog current or voltage signal which corresponds to an actual force signal.

10. The force sensor according to claim 8 , wherein the evaluation electronics on the circuit board are configured to convert a sensor signal into a digital actual force signal.

11. The force sensor according to claim 10 , wherein the evaluation electronics on the circuit board include a field bus interface configured to enable the sensor to be incorporated into a higher-order digital electrohydraulic hitch control system.

12. The force sensor according to claim 11 , wherein the field base interface is a CAN bus interface.

13. The force sensor according to claim 4 , wherein the change in material thickness is in the form of rounding.

14. The force sensor according to claim 3 , wherein the ratio is at least 6:1, 8:1 or 10:1.

15. The force sensor according to claim 1 , wherein the force sensor is configured for use with an electrohydraulic hitch control system of an agricultural tractor.

16. A force sensor, comprising:
a monolithic outer cylindrical part with a bore extending axially therethrough, the outer cylindrical part having a central section and two outer sections spaced equally far axially from a center of the central section; and
a measuring rod fixed in the bore at one of two axially spaced ends of the measuring rod, wherein:
the central section of the cylindrical part is a force introduction section that receives an external force to be measured by the force sensor,
the two outer sections are abutment sections configured to be fixed in position relative to one another, and
the measuring rod is clamped in the bore in at an axial location of the force introduction section.

Assignees

• Bosch Gmbh Robert

Inventors

• Thierbach Peter
• Klein Steffen

Classifications

• A01B61/02 Primary

  of the coupling devices between tractor and machine · CPC title

• A01B59/069

  with means for weighing the implement · CPC title

• G01L5/136

  Force sensors associated with a vehicle traction coupling (vehicle connections B60D; control of vehicle brakes B60T) · CPC title

• G01L1/044

  of leaf springs · CPC title

• G01L1/122

  by using permanent magnets · CPC title