WO2014079692A1

WO2014079692A1 - Plausibility checking method

Info

Publication number: WO2014079692A1
Application number: PCT/EP2013/073227
Authority: WO
Inventors: Anton Siemens
Original assignee: Robert Bosch Gmbh
Priority date: 2012-11-20
Filing date: 2013-11-07
Publication date: 2014-05-30
Also published as: CN104937286A; DE102012221127A1; CN104937286B

Abstract

The invention relates to a plausibility checking method for checking the plausibility of pressure values that are measured by means of a sensor device (32, 33) in a hydraulic system, which comprises a primary drive (11) and a hydraulic secondary drive (12), which is drivingly connected to the primary drive (11). In order to create a plausibility checking method that can be checked simply and economically, a power P0 of the primary drive (11) and a power P1 of the hydraulic secondary drive (12) are determined and used to check the plausibility of hydraulic pressure values measured by the sensor device (32, 33) at an outlet of the hydraulic secondary drive (12).

Description

description

title

Plausibility examination procedure

The invention relates to a plausibility check method for checking the plausibility of pressure values which are detected by a sensor device in a hydraulic system comprising a primary drive and a hydraulic secondary drive, which is drivingly connected to the primary drive. The invention further relates to a computer program product comprising a computer program having software means for performing such a plausibility check method when the computer program is executed on a computer. The invention further relates to a hydraulic drive having a hydraulic system in which such a plausibility check method is performed.

State of the art

In hydraulic systems, the knowledge of the pressure under control engineering, control technology and / or monitoring technical aspects plays an important role. The pressure can be detected, for example, with a pressure sensor. In order to detect operationally relevant deviations, sensor failures or unwanted drifting, it is necessary to make the pressure values recorded with the pressure sensor plausible.

Disclosure of the invention

The object of the invention is to provide a plausibility check method, with which the plausibility of pressure values which are detected by a hydraulic sensor device in a hydraulic system, can be easily and inexpensively checked. The hydraulic system includes a prime mover and a secondary hydraulic drive that is drivingly connected to the prime mover.

The object is achieved in a plausibility check method for plausibilizing pressure values which are detected by a sensor device in a hydraulic system comprising a primary drive and a secondary hydraulic drive, which is drivingly connected to the primary drive, in that a power PO of the Primary drive and a power P1 of the secondary drive are determined and used to plausibilize hydraulic pressure values detected at an output of the hydraulic secondary drive from the sensor device. The hydraulic secondary drive is preferably a hydraulic machine with a pump function and a motor function. The hydraulic machine can be designed, for example, as an axial piston machine. In the context of the present invention, it has been found that the plausibility of the pressure values recorded with the sensor device, for example a pressure sensor, on the power of the primary drive and the power of the secondary drive can be checked simply and inexpensively. By means of the plausibility check method according to the invention, a continuous determination of the pressure present at an output, in particular a high-pressure side of the hydraulic secondary drive, in particular a hydraulic machine with a pump function, with the aid of a power balance or a torque balance on the secondary hydraulic drive is simplified considerably , As a result, it is possible to dispense with an otherwise required, redundant pressure sensor or a more complex signal plausibility check.

A preferred embodiment of the plausibility check method is characterized in that the power P1 of the secondary drive is calculated taking into account losses from the power PO output by the primary drive. In operating points in which no additional power or only a known power flows off at a branched transmission, the power P1 of the secondary drive, taking into account the losses, in particular of transmission losses and / or clutch losses, from the output power PO of the prime mover is known or can be determined. A further preferred embodiment of the plausibility check method is characterized in that the output from the primary drive power PO is determined from known operating parameters. The known operating parameters are, for example, an injection quantity, air parameters, rotational speeds and the like. The power PO and possibly the power P1 can or can be determined or calculated in a motor vehicle-internal control unit.

A further preferred embodiment of the plausibility check method is characterized in that an effective torque M1 of the secondary hydraulic drive is determined by means of the following equation (1):

M1 = P1 / n1 = P0 / n1 = M0 ^* n0 / n1 (1).

NO stands for the speed of the primary drive. n1 stands for the speed of the hydraulic secondary drive. MO stands for the torque output by the prime mover, minus the losses.

A further preferred embodiment of the plausibility test method is characterized in that a strong, almost linear relationship is assumed between the torque M1 of the secondary hydraulic drive and a differential hydraulic pressure dp across the hydraulic secondary drive for a constant displacement level vg of the hydraulic secondary drive. The degree of adjustment vg of the hydraulic secondary drive is, for example, a swivel angle of a hydraulic machine with a pump function and an engine function, in particular an axial piston machine. The degree of adjustment vg can be measured during operation of the hydraulic machine. The hydraulic differential pressure dp is a pressure difference between an output and an input of the secondary hydraulic drive. The pressure at the output of the secondary hydraulic drive is also referred to as high pressure. Similarly, the pressure at the inlet of the secondary hydraulic drive is called low pressure. A further preferred embodiment of the plausibility check method is characterized in that the effective torque M1 of the secondary hydraulic drive is determined by means of the following equation (3):

M1 = vg ^* dp ^* k + M _Leak (vg.dp.n) (3).

Equation (3) with vg ^* dp ^* k contains an explicitly linear, analytical component. The factor k is a constant which is determined from measurements or the geometry data. M _Leak represents the loss / friction torque and thus the deviation from the linear relationship, which can be stored, for example, in a characteristic map.

A further preferred exemplary embodiment of the plausibility check method is characterized in that the formulaic relationship recorded with the aid of equation (3) is stored or stored, for example in the form of a characteristic field. The formulaic relationship shown in equation (3) can be inverted and remains unique in terms of pressure and moment. Thus, this relationship and also the inverse context, for example, be stored as a map in a control unit.

Another preferred embodiment of the plausibility check method is characterized in that a physical pressure p at the output of the secondary hydraulic drive is determined using the following equation (5): p = dp (M1, vg, n) -p _ND (5).

Here, p _ND stands for the pressure at the input of the hydraulic secondary drive. This pressure is also called low pressure. The calculation of the physical pressure p by means of equation (5) is very accurate for steady state and quasi-steady state operation. With high dynamics, the inertia in the system may need to be taken into account in the power balance. The invention further relates to a computer program product comprising a computer program having software means for performing a plausibility check method described above when the computer program is executed on a computer. For example, the computer may be represented by an in-vehicle controller.

The invention further relates to a hydraulic drive with a hydraulic system in which a plausibility check method described above is performed. The hydraulic drive is preferably designed as a mobile hydraulic drive and serves to represent a hydraulic hybrid vehicle.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail.

Short description of the drawing

In the single accompanying figure, a part of, for example, a mobile hydraulic drive to illustrate the plausibility check method according to the invention is shown greatly simplified.

Description of the embodiment

In the accompanying figure, a mobile hydraulic drive 10 with a primary drive 1 1 and a hydraulic secondary drive 12 is shown. In the primary drive 1 1 is an internal combustion engine 15, which is also referred to as an internal combustion engine. The hydraulic secondary drive 12 is a hydraulic machine 16 with a pump function and a motor function. The hydraulic machine 16 is advantageously designed as an axial piston machine. The delivery volume of the hydraulic machine 16 is adjustable. The associated degree of adjustment is referred to below as vg.

Arrows 17 and 18 indicate that the primary drive 1 1 is drivingly connected to the secondary hydraulic drive 12. In this case, the primary drive 1 1 can be used to drive the hydraulic secondary drive 12. The hydraulic secondary drive 12 can also be used to drive the Primary drive 1 1 can be used. Between the arrows 17 and 18 is indicated by a symbol 20 that additional inputs / outputs, transmission, (mechanical) translations, power splitter driving between the prime mover 1 1 and the hydraulic secondary drive 12 may be connected.

The hydraulic secondary drive 12 or the hydraulic machine 16 is connected to a hydraulic medium reservoir 23 on a low-pressure side. By an arrow 24 is indicated that with the hydraulic machine 16 in its pump function hydraulic medium from the

Hydraulic medium reservoir 23 is sucked and conveyed to a high-pressure side in a pressure accumulator 25.

The pressure accumulator 25 is used to store with pressure, in particular high pressure, acted upon hydraulic medium. Via a storage valve 26 high-pressure hydraulic medium can be dispensed from the pressure accumulator 25 as needed. The pressurized hydraulic fluid from the accumulator 25 can be used to drive the hydraulic machine 16 in its engine function and / or for operating other hydraulic machines or consumers in the system.

By means of a hydraulic connecting line 28, further hydraulic components, in particular hydraulic consumers and / or hydraulic generators, can be connected to the outlet or the high-pressure side of the hydraulic machine 16 or of the hydraulic secondary drive 12.

By a rectangular symbol 31 is indicated that the pressure in the

Hydraulic medium reservoir 23, which is also referred to as low pressure, is detected with a suitable pressure sensor. By a further rectangular symbol 32 is indicated that the high pressure in the pressure accumulator 25 can be detected with a suitable pressure sensor. By a further rectangular symbol 33 is indicated that the high pressure in the hydraulic connection line 28 is detected by a suitable pressure sensor. At a point 35 adjacent to the rectangular symbol 33 there is a physical pressure p, which can be determined with the aid of the plausibility check method described below. The letter P is used to designate services. To denote torques, the letter M is used. To denote speeds, the letter n is used. The letter p is used to denote pressures. In detail, the letter-number combinations used in the following equations (1 to 5) have the following meanings: PO = power of the prime mover 1 1 or of the internal combustion engine

15;

P1 = power of the hydraulic secondary drive 12 or the hydraulic machine 16;

MO = torque of the prime mover 1 1 and the internal combustion engine 15;

M1 = torque of the secondary hydraulic drive 12 or the hydraulic machine 16; NO = speed of the prime mover 1 1 or the internal combustion engine 15; n1 = speed of the hydraulic secondary drive 12 and the hyd raulischen machine 16; vg = degree of adjustment of the hydraulic machine 16; dp = differential pressure; p = physical pressure;

PND = low pressure;

M | _ea _k = loss / friction torque; k = constant.

The plausibility check method according to the invention makes it possible to determine the physical pressure p at point 35 in the hydraulic system, which is illustrated in simplified form in the attached figure. The plausibility check method according to the invention serves to monitor or check the plausibility of pressure values detected with the pressure sensor 33.

As a result, a continuous determination of the pressure applied to the high-pressure side of the hydraulic machine 16 by means of a power balance on the hydraulic machine 16 is made possible in a simple manner. On an additional, redundant pressure sensor or a more complex

Signal plausibility can be waived.

The plausibility check method can be advantageously used in a serial hybrid drive, as a part thereof is shown in simplified form in the attached figure. In this case, the hydraulic machine 16 is driven in its pump function by the internal combustion engine 15 in order to generate at its output a pressure or volume flow.

The plausibility test method works with a clearly calculable physical relationship between a pump torque and a hydraulic pressure, as is the case, for example, in Axialkolbenverstellmaschinen, especially Axialkolbenverstellmotoren or pumps, with a swash plate or hydraulic machines, especially pumps, with adjustable pivot axis. A prerequisite is the knowledge of the power absorbed by the hydraulic machine 16, in particular in its pump function.

In operating points at which no power or only a known power flows off at a branched transmission, the power of the hydraulic machine 16 P1 is known taking into account the transmission / clutch losses from the output power PO of the internal combustion engine or of the internal combustion engine 15. The power PO and possibly the power P1 is or are calculated in a control unit from injection quantity, air parameters, speed, et cetera. From the known rotational speeds nO of the internal combustion engine 15 and n1 of the hydraulic machine 16, the effective torque M1 of the hydraulic machine 16 can be determined therefrom. Neglecting the losses:

M1 = P1 / n1 = P0 / n1 = MO ^* nO / n1 (1).

Between the torque of the hydraulic machine 16 and the differential pressure dp over the hydraulic machine 16, that is between low pressure and high pressure, there is a strong, almost linear relationship for a constant pivot angle or degree of adjustment vg. The actual swivel angle or degree of adjustment vg of the hydraulic machine 16 can be measured.

For the degree of adjustment vg, the differential pressure dp and the effective torque M1 of the hydraulic machine 16, the general context applies:

M1 = M (vg, dp, n) (2), or with an explicit linear, analytical component: M1 = vg ^* dp ^* k + M _Leak (vg, dp, n) (3).

The factor k is a constant which is determined from measurements or the geometry data. M _Leak represents the loss / friction torque and thus the deviation from the linear relationship, which can be stored in a characteristic map, for example.

The relationship can be inverted and remains clear regarding pressure and moment. For example, it can be stored as a map in a control unit. Then, depending on the degree of adjustment, the speed and the torque stored: dp = dp (M1, vg, n) (4).

Knowing the low pressure p _ND , for example by the low pressure sensor 31 or from an estimate, the physical high pressure p can be determined as follows: p = dp (M1, vg, n) - p _ND (5).

This calculation is very accurate for steady state and quasi stationary operation. With high dynamics, the inertia in the system may need to be taken into account in the power balance. The inertia in the system is, for example, an inertia of a transmission and an inertial moment of the hydraulic machine 16 or an inertia of the adjustment system et cetera.

If a further pressure sensor 32 is present in the high pressure, for example in the pressure accumulator 25, the two sensors 32 and 33 can also be checked against one another when the accumulator valve 26 is open. The two mutually tested pressure values detected by the sensors 32 and 33 can be compared with the physical pressure p determined by the above-described plausibility check method. The result of the comparison can then be used to adapt or map the map to the individual system as long as the pressure values detected by the pressure sensors 32, 33 are considered to be free from errors.

Claims

claims

1 . Plausibility check method for plausibility checking of pressure values which are detected by a sensor device (32, 33) in a hydraulic system which comprises a primary drive (11) and a secondary hydraulic drive (12) which is drivingly connected to the primary drive (11) , characterized in that a power PO of the primary drive (1 1) and a power P1 of the hydraulic secondary drive (12) are determined and used to hydraulic pressure values detected at an output of the hydraulic secondary drive (12) from the sensor device (32,33) plausibility.

2. plausibility testing method according to claim 1, characterized in that the power P1 of the hydraulic secondary drive (12) is calculated taking into account losses from the output from the primary drive (1 1) power PO.

3. Plausibility testing method according to one of the preceding claims, characterized in that the output from the primary drive (1 1) power PO is determined from known operating parameters.

4. plausibility test method according to any one of the preceding claims, characterized in that an effective torque M1 of the hydraulic secondary drive (12) by means of the following equation (1) is determined:

M1 = P1 / n1 = P0 / n1 = M0 ^* n0 / n1 (1).

5. plausibility test method according to claim 4, characterized in that between the torque M1 of the hydraulic secondary drive (12) and a differential hydraulic pressure dp above the hydraulic secondary drive (12) for a constant degree of adjustment vg of the hydraulic secondary (12) is assumed to be strong, almost linear.

Plausibility check method according to claim 4 or 5, characterized in that the effective torque M1 of the secondary hydraulic drive (12) is determined by means of the following equation (3):

M1 = M (vg, dp, n) respectively

M1 = vg ^* dp ^* k + M _Lea k (vg.dp.n) (3).

A plausibility check method according to claim 6, characterized in that the formulaic relationship and the inverse relationship: dp = dp (M1, vg, n) detected by means of equation (3) are stored or stored, for example in the form of a characteristic field.

Plausibility check method according to one of Claims 5 to 7, characterized in that a physical pressure p at the output of the secondary hydraulic drive (12) is determined by means of the following equation (5): p = dp (M1, vg, n) -p _ND (5).

A computer program product comprising a computer program comprising software means for performing a plausibility check method according to any one of the preceding claims when the computer program is executed on a computer.

0. Hydraulic drive with a hydraulic system in which a plausibility check method according to one of the preceding claims is performed.