GB2189052A - Controlling a number of valves - Google Patents

Abstract

A control mechanism for a Change Speed Gear a fuel supply valves in motor vehicles has a number of control elements. Pressure medium is supplied to each control element via a control valve 10,20,30 constructed as a combined electromagnetic pilot and pressure control valve. The force acting on the valve body 11 can be regulated by changing the magnetic field force. Appliance 17 sends a voltage indicating the instantaneous magnetic induction to an integrating element 51. By comparing the actual value given by the integrating element 51 and a desired value specified by a control circuit 9, which is determined by operating parameters, comparator 50 produces a signal for the electromagnet. A timing element limits the duration of the control operation of the regulating element 50 beginning with the triggering of a change of the Change Speed Gear. <IMAGE>

Description

SPECIFICATION Control mechanism for a number of control valves, preferably for a change speed gear The invention relates to a control mechanism for a number of control valves, preferably for a Change Speed Gear, in particular multistage tooth-wheel gearing for motor vehicles, which can be switched while loaded, and which has control elements in the form of friction clutch components and/or friction brake components actuated by pressure medium for switching in or switching over the individual gear speeds with the supply of pressure medium to each control element being influenced by one control valve respectively and there being provided a control circuit which triggers a commutation of the Change Speed Gear depending on various operating parameters, such as, for example, the driving speed and/or output speed of the Change Speed Gear and/or the position of the fuel feeder.

With such Change Speed Gears it is important to avoid interruptions in power transmission to a large extent during the switching operation which occurs under load, and which can also take place both in the traction operation and also in the thrust operation. It is particularly important that the gearing can be switched over between the individual switching stages without any jerks and bumps as far as possible.

From DE-AS 25 41 600 is known a control mechanism of the above-mentioned type, in which the control valves are constructed as hydraulic valves, the piston valve of which is actuated on the one hand by an operating piston and on the other hand by a cushion plunger, which operates in opposition to this.

Pressure medium is supplied to the operating piston via separate pilot valves, which are actuated electrically. So as to enable individual pressure control during the switching operation, this control mechanism in addition has one or several venting shut-off valves, by which the relief of the clutch or brake components can be temporarily delayed. However one disadvantage of this known control mechanism is the high number of valves and pressure medium lines used on account of the purely hydraulically operated control valves, which in addition make electromagnetic pilot valves and also the venting shut-off valve necessary. A further disadvantage is that the time slope of the regulated pressure build-up is governed in particular by the use of throttles in the control lines, and therefore can not be adapted to the operating parameters.

The use of components is also considerable in a switching device operated by pressure medium which is known from DE AS 18 17467, as here too for each Change Speed Gear component firstly a control valve operated by pressure medium and in addition an electrically operated control valve are provided.

DE-PS 22 09 447 describes a hydraulic switching mechanism having switching pressure control, which for each gear control element has a pressure medium control valve and a joint pressure control valve for all gear control elements. At the same time the pressure control valve can be controlled by means of electrical signals so that the pressure medium pressure is temporarily reduced for each switching operation, with the beginning and the end of the pressure reduction being freely adjustable by means of individual time switch components. However the level of the pressure reduction can only be regulated as a function of the position of the fuel feeder and only uniformly in the whole hydraulic system, i.e. not individually in each pressure medium line.Consequently the following is the result: If during a gear change (unloading a previously switched-in control element and loading another control element) a third gear control element is to remain switched in, then there is the danger that this third control element temporarily slips (risk of premature wear).

The object of the invention is to construct a control mechanism of the type mentioned at the beginning so that for each gear control element to be switched in it is possible to have short-term individual pressure control together with a small number of components being required, and consequently increased operational safety. Moreover it is to be possibie to control the pressure or the pressure build-up respectively, in particular depending on the gear control element to be switched in, and furthermore depending on the switching direction (changing up or changing down) and also on the operating parameters, such as, for example, the travelling speed, the engine loading, the position of the fuel feeder etc. If necessary it is also intended to be possible to control the duration of the pressure control in dependence on one or several of the abovementioned magnitudes.

The object is achieved in accordance with the invention in that the control valve is constructed as a combined electromagnetic pilot and pressure control valve, in which the force of the armature of the electromagnet acting on the valve body and displacing it can be regulated by changing the magnetic field force, in the electromagnet there being an appliance for producing a measuring voltage proportional to the temporary induction change for determining a measured variable forming the actual value (x) for the instantaneous magnetic induction and consequently the magnetic force produced, to which at least one integrating element is connected, which converts the measuring voltage into the measured variable proportional to the induction, in that furthermore a regulating element is provided, which produces a control quantity (y) for the induction current of the electromagnet by comparing the actual value (x) given by the integrating element and a desired value (w) specified by the control circuit, so that the magnetic force and also the pressure of the pressure medium actuating the control element is regulated to a value corresponding to the desired value, and in that finally a timing element is provided, which limits the duration of the control operation of the regulating element beginning with the triggering of a changing of the Change Speed Gear, so that subsequently the actual value and/or the desired value assumes a minimum or maximum value.

The progress achieved by the invention lies primarily in that it is possible to have individual control for the pressure of the pressure medium and in particular for its time slope depending on various operating parameters of significance to the switching operation whilst using a small number of hydraulic components, i.e. only one control valve for each control element of the gear to be actuated.

A control valve suitable for this is known, for example, from DE-AS 20 19345. The pressure control valve described therein is fitted with an electromagnet, the magnetic force of which can be regulated to control the pressure by using a regulator. For this purpose the pressure control valve is also fitted with a pick-up element for determining the force of the magnetic field, the signal size of which is used for the control.

Essentially this pick-up element can be formed in the way described by a resistance dependent on the magnetic field or even by a Hall generator.

Because of the mechanical and thermal sensitivity and also the temperature dependence of the output signal of these elements, when using such control valves in vehicle gear units, the provision of an auxiliary winding in the form of an induction loop is recommended for determining the instantaneous magnetic induction. Likewise for this purpose the operating winding inducing the magnetic field itself may however be used, and both steps have already essentially been disclosed in DE AS 20 19345. German Utility Model G85 29 255.9 also describes a suitable pressure control valve.

The last two possibilities for measuring the magnetic field are offered in particular within the scope of the invention, as here a single pressure control operation only lasts a few seconds. As a result signal errors occuring in the integration elements because of inavoidable offset voltages and voltage drift, at any rate with longer integration times, remain small enough, so that they remain insignificant and can be disregarded.

In a first embodiment of the invention each control valve can be provided with its own integrating and/or timing and/or regulating element. An extremely universal control facility is given by this.

When switching over from one gear stage to another it is sufficient to disengage the control element to be released directly, i.e.

without pressure regulation, and to control for a short time only the pressure of the control element about to be actuated. In a preferred embodiment of the invention a common integrating, timing and regulating element is therefore provided for all control valves. This is made possible by the following design features. The. integrating element is connected to the auxiliary winding of the respective control valve via a shift mechanism actuated by the control circuit and the control quantity of the regulating element is transmitted to the electromagnet of the respective active control valve also via said shift mechanism actuated by the control circuit. As a result it is possible to reduce the number of electrical or electronic components, which would otherwise be required, to a considerable extent. The shift mechanism may be formed in a particularly simple way by a multiplex element.

The timing element is advantageously arranged between the integrating element and the actual value input of the regulating element and at the end of the time-limited control operation sets the actual value to its minimum value, so that the control quantity assumes its maximum value. In this way it is ensured that at the end of the control time period determined by the timing element the respective control element switched in is fully pressurised. However the control mechanism may also be constructed so that the time switching element resets the integrating element to zero for ending the control operation, as a result of which the integrating element is already in its initial position for the next switching operation.

Finally there is also the possibility of arranging the timing element between the control circuit and the regulating element and, to end the control operation, of it setting the desired value to a maximum value, so that the control quantity assumes its maximum value.

Moreover the control circuit can produce an individual desired value for each switching operation. Furthermore, an individual timing element can be provided for each switching operation.

The invention is explained in more detail below with reference to the exemplified embodiments shown in the drawings. They show: Figure 1 the control mechanism according to the invention in a diagrammatic representation, Figure 2 a further embodiment of the object according to Fig. 1, but only a partial representation, Figure 3 an axial section through one of the control valves, Figure 4 a detailed representation of the object according to Fig. 1 in a further embodiment.

The control mechanism shown in Fig. 1 is provided for a Change Speed Gear, in particular for multistage tooth-wheel gearing for motor vehicles, which can be switched while loaded. To switch in or switch over the individual gear shift stages, the gear shift in Fig. 1 has control elements, not illustrated, in the form of clutch and/or brake components, which are actuated by pressure medium, and which are operated via pressure medium lines 15, 25, 35. Thus, to given an example, to engage first gear the control element connected to line 15 can be actuated, with the other lines 25 and 35 being simultaneously free from pressure. Accordingly in second gear line 25 is impinged with pressure, while lines 15 and 35 are free from pressure.The invention is explained below using this simple example, in which only one of the pressure medium lines 15, 25 or 35 is impinged with pressure in each gear. However the invention can also be used in Change Speed gears in which several (preferably two) control elements have to be simultaneously operated by pressure impingement in each gear.

The supply of pressure medium to each control element is influenced respectively by one control valve 10, 20, 30, the individual control valves 10, 20, 30 being connected via a common supply line 5 to a pump 6, which produces the required control pressure. A pressure control valve 6a keeps the pressure in line 5 at a constant value. Finally a control circuit 9 is provided which triggers a commutation of the Change Speed Gear depending on various operating parameters of the gearing or of the vehicle. With these operating parameters, the determination of which is not shown in more detail in the drawings, it concerns, for example, the driving speed and/or output speed of the Change Speed Gear and the position of the fuel feeder M, which represents a measure for the engine loading.From these operating parameters the control circuit 9 forms 9 commands for gear changing: from idling to gear 1 (line 01), from gear 1 to gear 2 (line 12), from gear 2 to gear 3 (line 23), from gear 3 to gear 2 (line 32), from gear 2 to gear 1 (line 21).

By this the control circuit 9 determines which switching stage is to be switched in next.

Each control valve 10, 20, 30 is constructed as a combined electromagnetic pilot and pressure control valve, preferably according to Fig. 3. I.e., taking control valve 10 as an example: As a pilot valve it connects pressure medium line 15 either to supply line 5 or to discharge line 18. Moreover as a control valve it can regulate the pressure in the pressure medium line 15 to a specified value for a short time. During such a pressure regulating operation the force of the armature 22 of the electromagnet 16 acting on the valve body 11 and displacing it can be adjusted by changing the magnetic field force. In detail the valve body 11 is constructed in the shape of a cup and is axially displaceable via an actuating pin 22' connecting with the armature 22.The valve body 11 is divided in a valve housing 11' into three inner chambers 24, 26, 28 by two annular flanges 1 1a, 1 1b disposed behind one another in the axial direction and guiding the valve body 11. The middle inner chamber 26 is connected to the pressure medium source 6 via supply line 5, while inner chamber 24 is connected via pressure medium line 15 to a control element 8, shown here as a circle, in the region of the open end of the valve body 11. From the inner chamber 28 adjacent to the electromagnet 16 a discharge line 18 leads to the outside, for example into a sump 14.

In the region of its base, the valve body 11 is provided with radially extending bore holes 13, the diameter of which is at most equal to the width of annular flange 11 b, so that the bore holes 13 are completely or nearly completely covered by annular flange 11 b with a corresponding position of the valve body. In this "pressure regulating position", in which the bore holes 13 are symmetrical to the annular flange 11 b, equilibrium between the displacement forces acting on the valve body 11 can occur-for the duration of a regulating operation described in more detail below. I.e. the magnetic force transmitted from the pin 22 is in this position equal to the compressive force acting on the valve body 11 from the pressure in line 15.If the magnetic force is less than the said compressive force, in particular when the electromagnet is switched off, then the valve body 11 is displaced from the pressure regulating position" to the electromagnet 16. As a result there is a free (unthrottled) connection between the control element 8 and the sump 14 via bore holes 13, as a result of which the control element is relieved. When the valve body 11 is displaced in the opposite direction, triggered by the setting of the magnetic force to its unregulated maximum value, the inner chambers 24 and 26 are however connected to one another and consequently pump 6 is connected to control element 8.

During the pressure regulating operation, which always occurs at the beginning of the supply of pressure medium to a control element 8 to be newly switched in and the duration of which is limited, the induction current of the electromagnet 16 can be regulated, as is diagrammatically shown in Fig. 1. To detect the magnetic force the electromagnet 16 has an auxiliary winding 17 arranged in the region of the operating winding 16'. The connections of the auxiliary winding 17 are designated by 1 7a and 17b, and the connections of the op erating winding 16 by 16a and 16b. The voltage induced in the auxiliary winding 17 is proportional to the time change of the magnetic induction.It is supplied via lines 17a, 17c to an integrating element 51, which forms, by chronological integration (as is known from DE-AS 20 19 345), a voltage directly proportional to the magnetic induction.

This is simultaneously a measure for the instantaneous field force and consequently the magnetic force produced and serves as a measured variable forming the actual value.

Moreover a regulating element 50 is provided, which produces a control quantity y for the induction current of the electromagent 16 by comparing the actual value x (emitted by the integrating element 51 via lines 53,53') with a desired value w, so that the magnetic force and moreover the pressure of the pressure medium (line 15) actuating the control element is regulated to a value corresponding to the desired value w. This control quantity y is supplied via a line 52, 52' to an electrically controllable control element, e.g. to a switching transistor 19, which adjusts the magnetic current (line 16a) according to the control quantity y of regulating element 50. All switching transistors are connected to a current source 161 via a supply line 160.Finally there is provided a timing element 49, which limits the duration of the control operation of regulating element 50 beginning with the triggering of a commutation of the Change Speed gear so that subsequently the actual and/or desired value assumes a minimum or maximum value.

It is important that the control circuit 9 forms an individual desired value for each shift operation, the said desired value being supplied (simultaneously with the giving of the appropriate shift command) through one of lines 01', 12',23', 32' or 21' to a digital analogue transformer 39 and from there as an analogue signal via line 48 to regulating element 50.

Basically it is possible that each control element 10, 20, 30 is provided with its own integrating, timing or regulating element 51, 49, 50, by which are given universal control and regulation facilities, which admittedly entail a greater number of electric or electronic structural groups. However, depending on the individual application, it will be sufficient to provide just some of these elements several times. Fig. 2 shows in detail that, for example, each switching operation can be provided with its own timing element 490 to 494. Every time that the control circuit 9 emits a shifting command, one of the timing elements is activated via the appropritate signal line 01, 12, 23, 32 or 21. Consequently the duration of the pressure regulation can be set individually for each shifting operation.

However within the scope of the invention there is also the particularly advantageous facility of providing all control valves with common integrating, timing and regulating elements 51, 49, 50, with the integrating element 51 being connected to the respectively active auxiliary winding 17 (line 17a, 17c) via a shift mechanism 40 and the control quantity y of regulating element 50 being transmitted to the respectively active electromagnet 16 via the same shift mechanism 40 actuated by the control circuit 9 through signal lines 01, 12, 23, 32, 21. This shift mechanism 40 can be formed in a particularly simple manner by a multiplex element in integrated Change Speed Gear technology. Fig. 1 diagrammatically shows that the shift mechanism 40 has four switching positions: N (idling) and I, II, Ill for gears 1 to 3.

In the exemplified embodiments shown in the drawings the timing element 49 (or timing elements 490 to 494) is arranged respectively between the integrating element 51 and the actual value input of regulating element 50.

This timing element 49 sets the actual value at its minimum value at the end of the timelimited control operation, as a result of which the control quantity y emitted by regulating element 50 assumes its maximum value. The control valve 10, 20, 30 respectively controlled thus loads the associated control element with maximum pressure. However, likewise to end the control operation, the timing element 49 may reset integrating element 51 to zero, so that in return the actual value assumes its minimum value, as a result of which the integrating element 51 is already in its initial position for the next switching operation.

Alternatively, as shown in Fig. 1 by dotdash lines, timing element 49' may also be disposed between control circuit 9 and regulating element 50, which, however, then sets the desired value to its maximum value at the end of the time-limited regulating operation, as a result of which the control quantity also assumes its maximum value.

Finally Fig. 4 shows an exemplified embodiment having a control valve lo, in which the induction winding of the electromagnet 16 is itself used to determine the ipstantaneous magnetic induction. For this purpose in the circuit of voltage source 161 via switching transistor 19 and induction winding 66 of the electromagnet a precision resistor RM is connected in series, and this causes a voltage drop, from which the measured variable proportional to the induction can be formed.

As the voltage drop at the precision resistor contains a constant direct voltage component, this primarily has to be supressed by a differentiating circuit 67 and its output signal subsequently has to be integrated in a first integrating element 71 to recover the original signal. As this voltage is proportional to the current variation in the magnet 16, a second integration integrating element 72 is required, which then supplies a voltage proportional to the magnetic field present in the electromagnet 12, the further processing of which is carried out in a way evident from Fig. 1.

The invention can also be used in a fuel feeding appliance for a multi-cylinder internal combustion engine. Herein one fuel atomizer valve (also called "Fuel Feeding Valve") is assigned to each cylinder as is generally known.

With reference to Fig. 1, this means that a fuel pump 6, a main fuel line 5, several fuel feeding valves 10, 20, 30, and several fuel branch lines 15, 25, 35 are provided which lead to the individual cylinders of the internal combustion engine.

Claims (13)

1. A control mechanism for a number of control valves, eg fuel feeding valves of a multistage tooth-wheel gearing for motor vehicles, which can be switched while loaded, and which has control elements in the form of clutch and/or brake components actuated by pressure medium for switching in or switching over the individual gear shift stages, with the supply of pressure medium to each control element being influenced by one control valve respectively and there being provided a control circuit, which triggers a commutation of the Change Speed Gear depending on various operating parameters, such as, for example, the driving speed and/or output speed of the gear-shift and the position of the fuel feeder, characterised in that the control valve (10, 20, 30) is constructed as a combined electromagnetic pilot and pressure control valve, in which the force of the armature (32) of the electromagnet (16) acting on the valve body (11) and displacing this can be regulated by changing the magnetic field force, in the electromagnet there being an appliance (17 or 66 respectively) for producing a measuring voltage proportional to the temporary induction change for determining a measured variable forming the actual value (x) for the instantaneous magnetic induction and consequently the magnetic force produced, to which at least an integrating element (51 or 71 respectively and 72) is connected, which converts the measuring voltage into the measured variable proportional to the induction, in that furthermore a regulating element (50) is provided, which produces a control quantity (y) for the induction current of the electromagnet (16) by comparing the actual value (x) given by the integrating element (51) and a desired value (w) specified by the control circuit (9), so that the magnetic force and also the pressure of the pressure medium actuating the control element is regulated to a value corresponding to the desired value (w), and in that finally a timing element (49) is provided, which limits the duration of the control operation of the regulating element (50) beginning with the triggering of a changing of the Change Speed Gear, so that subsequently the actual value (x) and/or the desired value (w) assumes a minimum or maximum value.

2. Control mechanism according to Claim 1, characterised in that the appliance (17) is formed by an auxiliary winding.

3. Control mechanism according to Claim 1, characterised in that the appliance (66) is formed by the operating winding inducing the magnetic field.

4. Control mechanism according to Claims 1 to 3, characterised in that each control valve (10, 20, 30) is provided with its own integrating element and/or timing element and/or regulating element (51, 49, 50).

5. Control mechanism according to Claims 1 to 3, characterised in that for all control valves (10, 20, 30) common integrating, timing and regulating elements (51, 49, 50) are provided and the integrating element (51) is connected to the measuring voltage generator (e.g. auxiliary winding 17) of the respective active control valve (e.g. 10) via a shift mechanism and the control quantity (y) of the regulating element (50) is transmitted to the electromagnet (16) of the respective active control valve (e.g. 10) via the same shift mechanism (40) actuated by the control circuit (9).

6. Control mechanism according to Claim 5, characterised in that the shift mechanism (40) is formed by a multiplex element.

7. Control mechanism according to Claims 1 to 6, characterised in that the timing element (49) is arranged between the integrating element (51) and the actual value input of the regulating element (50) and, at the end of the time-limited control operation sets the actual value (x) at its minimum value, so that the control quantity (line 52) assumes its maximum value.

8. Control mechanism according to Claim 7, characterised in that the timing element (49) resets the integrating element (51) to zero to end the control operation, as a result of which the integrating element (51) is already in its initial position for the next switching operation.

9. Control mechanism according to Claims 1 to 6, characterised in that the timing element (49') is arranged between the control circuit (9) and the regulating element (50) and to end the control operation sets the desired value (w) at its maximum value, so that the control quantity (y) assumes its maximum value.

10. Control mechanism according to one of Claims 1 to 9, characterised in that the control circuit (9) produces an individual desired value (line 01', 12', 23', 32', 21') for each switching operation (01, 12, 23, 32, 21).

11. Control mechanism according to one of Claims 1 to 10, characterised in that an individual timing element (490 to 494) is provided for each switching operation (01, 12, 23, 32, 21) (Fig. 2).

12. A control mechanism for a number of fuel feeding control valves of a multi-cylinder internal combustion engine with the supply of fuel to each cylinder being influenced by one control valve respectively and there being provided a control circuit, which triggers feeding of fuel to each of the cylinders, depending on various operating parameters, such as, for example, the driving speed and/or the position of the accelerator pedal, characterised in that the control valve (10, 20, 30) is constructed as a combined electromagnetic pilot and pressure control valve, in which the force of the armature (32) of the electromagnet (16) acting on the valve body (11) and displacing this can be regulated by changing the magnetic field force, in the electromagnet there being an appliance (17 or 66 respectively) for producing a measuring voltage proportional to the temporary induction change for determining a measured variable forming the actual value (x) for the instantaneous magnetic induction and consequently the magnetic force produced, to which at least an integrating element (51 or 71 respectively and 72) is connected, which converts the measuring voltage into the measured variable proportional to the induction, in that furthermore a regulating element (50) is provided, which produces a control quantity (y) for the induction current of the electromagnet (16) by comparing the actual value (x) given by the integrating element (51) and a desired value (w) specified by the control circuit (9), so that the magnetic force and also the pressure of the pressure medium actuating the control element is regulated to a value corresponding to the desired value (w), and in that finally a timing element (49) is provided, which limits the duration of the control operation of the regulating element (50) beginning with the triggering of feeding fuel to one of the cylinders, so that subsequently the actual value (x) and/or the desired value (w) assumes a minimum or maximum value.

13. A control mechanism for multistage tooth-wheel gearing for motor vehicles constructed arranged and adapted for use substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.