Pressure sensor with reduced measurement error

Abstract

A pressure sensor is provided. The pressure sensor includes a housing with a control and evaluation unit. A plurality of pressure ports are arranged at the housing of the pressure sensor, with a pressure measuring cell being associated with every pressure port. The pressure measurement cells are connected to the control and evaluation unit, and the pressure sensor has at least one digital output interface. At least one pressure port is a port for inserting a pressure line, with the pressure line being installable without tools and with the pressure line being surrounded by a seal of the pressure port and being secured against being pulled out.

Claims

1. A pressure sensor, comprising: a housing; a control and evaluation unit; a plurality of pressure ports arranged at the housing of the pressure sensor; and a plurality of pressure measuring cells, wherein each of the pressure measuring cells is in fluid communication with a respective one of the pressure ports, wherein the plurality of pressure measurement cells are connected to the control and evaluation unit, wherein the pressure sensor has at least one digital output interface, wherein at least one of the pressure ports is a port for inserting a pressure line, with the pressure line being installable without tools and with the pressure line being surrounded by a seal of the pressure port and being secured against being pulled out, wherein the pressure sensor further comprises at least one further pressure port, the at least one further pressure port comprising a G¼ IG, G¼ AG or ¼″ NPT pressure port, and wherein each of the pressure ports has a unique pressure range.

2. The pressure sensor in accordance with claim 1, wherein a first pressure range has the range from 0 to 10 bar and a second pressure range has the range from 0 to 16 bar.

3. The pressure sensor in accordance with claim 1, wherein a differential pressure measurement can be carried out between two of the pressure ports.

4. The pressure sensor in accordance with claim 1, wherein the at least one digital output interface is at least one TO link interface.

5. The pressure sensor in accordance with claim 1, wherein the at least one digital output interface is at least one Ethernet interface screw.

6. The pressure sensor in accordance with claim 1, wherein the at least one digital output interface is at least one fieldbus interface.

7. The pressure sensor in accordance with claim 1, wherein at least one control button is arranged at the housing.

8. The pressure sensor in accordance with claim 1, wherein at least one planar display is arranged at the housing.

9. The pressure sensor in accordance with claim 1, wherein the control and evaluation unit is programmable.

10. The pressure sensor in accordance with claim 1, wherein at least one temperature sensor is arranged in the housing, with the temperature sensor being connected to the control and evaluation unit.

11. The pressure sensor in accordance with claim 1, wherein at least one vibration sensor is arranged in the housing, with the vibration sensor being connected to the control and evaluation unit.

12. The pressure sensor in accordance with claim 1, wherein each of the pressure ports is connected to a corresponding one of the pressure measurement cells and the housing via a tube, with a plurality of the pressure measurement cells being fastened to a common printed circuit board.

13. The pressure sensor in accordance with claim 1, wherein each of the pressure ports is directly connected to the housing and each one of the pressure measurement cells is arranged on a respective separate printed circuit board.

Description

(1) The invention will also be explained in the following with respect to further advantages and features with reference to the enclosed drawing and to embodiments. The Figures of the drawing show in:

(2) FIG. 1 a schematic representation of a pressure sensor;

(3) FIG. 2 a further schematic representation of a pressure sensor;

(4) FIG. 3 a schematic representation of a pressure port;

(5) FIG. 4 a schematic representation of a pressure sensor in an application;

(6) FIG. 5 a housing of a pressure sensor;

(7) FIG. 6 a housing of a pressure sensor with control buttons and a display;

(8) FIG. 7 examples of pressure measurement cells;

(9) FIG. 8 a schematic representation of a printed circuit board with a pressure measurement cell;

(10) FIG. 9 a schematic representation of a printed circuit board with a pressure measurement cell;

(11) FIG. 10 a schematic representation of printed circuit boards with pressure measurement cells;

(12) FIG. 11 a schematic representation of a printed circuit board with connection webs and pressure measurement cells.

(13) In the following Figures, identical parts are provided with identical reference numerals.

(14) FIG. 1 shows a pressure sensor 1 having a housing 2 with a control and evaluation unit 3, wherein a plurality of pressure ports 4 are arranged at the housing 2 of the pressure sensor 1, wherein a pressure measurement cell 5 is associated with every pressure port 4, wherein the pressure measurement cells 5 are connected to the control and evaluation unit 3, wherein the pressure sensor 1 has at least one digital output interface 6, and wherein at least one pressure port 4 is a port for inserting a pressure line 21, with the pressure line 21 being installable without tools and with the pressure line 21 being surrounded by a seal 22 of the pressure port 4 and being secured against being pulled out.

(15) In this respect, for example, a plurality of pressure measurements of, for example, four, eight, sixteen or thirty two, or more individual pressure measurements are possible. In accordance with FIG. 1, eight pressure ports 4 are shown.

(16) FIG. 4 shows the pressure sensor 1 in an application having a vacuum gripper 28, a programmable logic controller 29, and a cloud 30. An example for such a use or application is a matrix of pneumatic vacuum grippers. These grippers are arranged in a pattern of 4×8, for example. Such a system receives the feedback as to which gripping procedure has been successfully carried out.

(17) The data evaluation and the data output by means of the control and evaluation unit 3 and the housing 2 are only present in a single version. A plurality of pressure values or process values can thereby be detected in the same housing 2.

(18) FIG. 5 shows by way of example a housing 2 having the pressure ports 4 on a mounting rail or top hat rail.

(19) FIG. 6 shows by way of example a housing 2 having the pressure ports 4 on a mounting rail or top hat rail, wherein the housing has a display 15 and control buttons 14. The pressure sensor 1 can be simply operated, parameterized, or configured using the control buttons 14. The control buttons 14 are, for example, formed as membrane keys or capacitive keys or similar. The planar display 15 is, for example, spatially associated with the control buttons 14. The display 15 and the control buttons 14 together form a user interface for inputting parameters or configurations and likewise for outputting diagnostic information, process data, pressure values, and/or temperature values.

(20) In accordance with FIG. 2, the control and evaluation unit 3 is programmable. The control and evaluation unit 3 has a memory 23 for this purpose. The control and evaluation unit 3 in particular also has an additional program memory 24 to store and execute user programs. The user programs can be executed on the control and evaluation unit 3 of the pressure sensor 1. Individual programs of the user or customer can thus be simply integrated on the pressure sensor 1. The output signals on the digital output interface can thus already be generated after the user program.

(21) Provision can, however, also be made that the pressure sensor 1 is also programmable via the anyway present firmware in the control and evaluation unit 3. A web-based or browser-based programming interface can be provided for this purpose.

(22) The pressure port 4 is, in accordance with FIG. 3, a port for inserting a pressure line 21, with the pressure line 21 being installable without tools and with the pressure line being surrounded by a seal 22 of the pressure port 4 and being secured against being pulled out. Such pressure ports 4 are also called push-in fitting ports. An installation of the pressure line 21 to be connected can take place simply manually without any tools being required. The pressure line 21 is inserted into a circular cylindrical mount for this purpose. On the pushing in, the pressure line 21 is surrounded by at least one annular seal 22 and is simultaneously latched, for example by means of an annular latching ring 25 having inwardly facing latching tongues 26 that are displaced or bent over by the introduced pressure line 21. If the tube is pulled, the latching tongues 26 cant or catch in the surface of the pressure line 21 and prevent a pulling out.

(23) To pull the pressure line 21 out, an annular unlatching device 27 that can likewise be actuated by hand without tools is provided at the pressure port 4. The annular unlatching device 27 is pressed in the direction of the pressure port 4, whereby the latching tongues 26 of the latching ring 25 are removed from the surface of the pressure line 21, whereby the pressure line 21 is no longer latched and the pressure line 21 can be removed and pulled out of the pressure port 4 simply by hand.

(24) Due to the simplicity of the pressure port 4 and due to flexible pressure lines 21, the pressure ports 4 can be used simply without the pressure ports 4 having to be exactly positioned and without threaded connections being provided, and the connection can be made without tools.

(25) The pressure ports 4 are preferably provided for a relative pressure measurement, for example. A relative pressure measurement relative to the environment takes place here. In this respect, every pressure measurement cell 5 belonging to the pressure port 4 is read in individually by the control and evaluation unit 3 and the measured value is provided or output by the control and evaluation unit 3 on the output interface 6. A processing, filtering, scaling, and/or calibration takes/take place between the reading and the output, for example.

(26) The pressure measurement cell 5 is obtained, for example in accordance with FIG. 7, as an SMD component and is mounted on a printed circuit board 18 in accordance with FIG. 8. An integrated pressure measurement cell 5 can have the following appearance:

(27) The adaptation to the process takes place by means of a mount at the upper side of the SMD component in accordance with FIG. 7 that is integrated with an exact fit and in a pressure tight manner in the housing 2. An O ring 31 is for this purpose, for example, placed around a nose of the pressure measurement cell 5 and takes care of the sealing between the housing 2, in particular the pressure port 4, and the SMD pressure measurement cell, in a cutout in the housing 2. The printed circuit board 18 is then fixedly screwed to the housing 2 in the region of the process port.

(28) This adaptation has to compensate the location tolerances between the printed circuit board 18, the mounting tolerances of the SMD components on the printed circuit board 18, and component tolerances and housing tolerances, and must simultaneously ensure the compressive strength of the process pressure.

(29) In accordance with FIG. 2, at least one further pressure port is a G ¼ IG 8, G ¼ AG 9 or ¼ NPT IO pressure port 4 of the pressure sensor 1. Different connections are thus provided at the pressure sensor 1, whereby the pressure sensor 1 can be used in a more versatile manner.

(30) A G ¼ IG 8 connection is a connection having a ¼ inch internal thread for a high pressure connection. A G ¼ AG 9 connection is a connection having a ¼ inch external thread for a high pressure connection. A ¼″ NPT IO connection is a connection having a ¼ inch external thread for a high pressure connection

(31) In accordance with FIG. 2, different pressure ports 4 are, for example, associated with different pressure ranges. Different pressure ranges can thereby be evaluated and monitored by a single pressure sensor 1. For example, at least one first pressure range has the range from 0 to 10 bar and at least one second pressure range has the range from 0 to 16 bar. There for further, for example, also pressure ranges from 0 to 1 bar, 0 to 6 bar, 0 to 16 bar, −1 to 0 bar, −1 to 1 bar, or −1 to 10 bar.

(32) A differential pressure measurement can, for example, be carried out between two pressure ports 4. In this process, for example, two pressure ports 4 or two pressure channels are used for the differential pressure measurement. A digital differential pressure measurement takes place here, for example, with two pressure channels or two pressure measurement cells 5 producing a digital differential pressure measurement value as an absolute value in each case. It is, for example, possible for all pressure ports 4, with two pressure ports 4 always forming a differential pressure channel. The differential pressure channel can also be provided for all the measurement ranges.

(33) Two pressure ports 4 or two process connections are provided, for example, per pressure channel in a differential pressure measurement. The pressure sensor 1 can also measure the difference between the two process connections using a single pressure measurement cell 5, that is a relative measurement. In contrast to the absolute measurement, this offers the advantage that only one single pressure measurement cell 5 is required per pressure channel. A differential pressure measurement using two independent pressure measurement cells 5, that is a respective absolute pressure measurement, produces higher measurement accuracy.

(34) A simple flow measurement between two pressure ports 4 can furthermore be provided. A diaphragm is arranged between the pressure ports 4 for this purpose and the pressure measurement cell 5 is configured to determine a flow quantity. This is in particular provided for small measurement ranges from 0 to 0.5 bar.

(35) In accordance with FIG. 4, the output interface is, for example, an IO link interface 11. Up to 32 bytes can be mapped via IO link process data. The number of possible pressure values in the process datum scales in dependence on the transferred pressure values.

(36) As already mentioned, handling units having a large number of pressure measurement sites represent an advantageous use of the multi-channel pressure sensor 1. The pressure sensor 1 is here seated directly on the gripper or robot arm. An actuator system that has to be controlled by a machine control is also located at this position of the handling unit. The pressure sensor 1 provides electrical output signals of the IO link interface 11 to further reduce the cabling effort between the handling unit and the control.

(37) Parameter inputs for the pressure sensor 1 by which a controller can switch the outputs of the pressure sensor 1 are provided via an interface, in particular the IO link interface 11.

(38) Pneumatic valves or electrical actuators can be switched by the output signals of the ID link interface 11. Additional digital input signals can be advantageous to evaluate further sensor signals such as the location information of grippers.

(39) In accordance with FIG. 4, a further output interface is, for example, an Ethernet interface 12.

(40) An Ethernet device can be an intelligent sensor, namely the pressure sensor 1, an actuator, a hub, or, however, due to the bidirectional communication, also a mechatronic component, e.g. a gripper having an Ethernet connection. With respect to an Ethernet device, intelligent means that a device, that is the pressure sensor 1, has identification data, e.g. a type designation and a serial number or parameter data, e.g. sensitivities, switching delays, or characteristics, that can be read or written over the Ethernet protocol. The changing of parameters can thus take place in part in ongoing operation by the PLC. But intelligent also means that the pressure sensor 1 can deliver detailed diagnostic information.

(41) The output interface is optionally a fieldbus interface. Provided fieldbuses are, for example Profibus, Interbus, CANopen, etc.

(42) In accordance with FIG. 2, at least one temperature sensor 16 is arranged in the housing, with the temperature sensor 16 being connected to the control and evaluation unit 3.

(43) The process temperature can, for example, be detected in this process. For example, the temperature of the pressure medium can be directly detected, whereby useful additional information on the process is available.

(44) The environmental temperature can, for example, also be detected. An additional useful process parameter is thus likewise available.

(45) The temperature or temperatures are detected and evaluated continuously or cyclically, for example.

(46) In accordance with FIG. 2, a vibration sensor 17 is arranged in the housing, with the vibration sensor 17 being connected to the control and evaluation unit 3.

(47) The vibration sensor 17 is, for example, directly connected to the housing of the pressure sensor 1. Vibrations of the process that have been caused can thus be recorded and analyzed.

(48) In accordance with FIG. 2 the pressure port 4 of the pressure measurement cells 5 is connected to the housing 2 via a tube 19, with a plurality of pressure measurement cells 5 being fastened to a common printed circuit board 18, in accordance with FIG. 9.

(49) Temperature influences and/or production tolerances between the PCB and the housing 2 can be compensated via a flexible connection between the pressure measurement cell 5 and the housing 2, for example via the tube 19. Mechanical displacements that occur can thus in particular be compensated on large temperature changes.

(50) In accordance with FIG. 10, the pressure port 4 of the pressure measurement cell 5 is directly connected to the housing and each pressure measurement cell 5 is arranged on a respective separate printed circuit board 18.

(51) The pressure port 4 or process connection of every pressure measurement cell 5 is here directly screwed in the housing 2. The connection of a pressure measurement cell printed circuit board and of a base module printed circuit board takes place, for example, via plug connectors or flat ribbon cables that enable a tolerance compensation.

(52) A cascadable solution is thereby provided with which pressure sensors 1 having a different number of pressure ports 4 can be implemented with an identical internal design. A large number of different variants of pressure sensors 1 can thereby be formed. For this purpose, a base module that is connected to or combined with a number of pressure measurement cells 5 is provided for the production of the pressure sensor 1. A modular system is thus formed.

(53) In accordance with FIG. 11 the pressure port 4 of the pressure measurement cells 5 is directly connected to the housing 2, with a plurality of pressure measurement cells 5 being fastened to a common printed circuit board, 18 with the printed circuit board 18 having connection webs between the printed circuit board parts of the pressure measurement cells 5.

(54) All the components are mounted on one printed circuit board here 18. The tolerance compensation works, for example, by a mechanical relief of the printed circuit board 18 by milled slots, whereby the connection that is left forms the connection web 20, or by partly flexible printed circuit boards e.g. at the connection sites, whereby the connection webs 20 are formed.

(55) Provision can, however, also be made to use only completely flexible printed circuit boards 18.

REFERENCE NUMERALS

(56) 1 pressure sensor 2 housing 3 control and evaluation unit 4 pressure port 5 pressure measurement cell 6 digital output interface 8 G ¼ IG 9 G ¼ AG 10 ¼″ NPT 11 IO link interface 12 Ethernet interface 14 control buttons 15 display 16 temperature sensor 17 vibration sensor 18 printed circuit board 19 tube 20 connection webs 21 pressure line 22 seal 23 memory 23 program memory 25 latching ring 26 latching tongues 27 unlatching device 28 vacuum gripper 29 programmable logic controller 30 cloud 31 O ring