SE528347C2 - System to ensure that the total force acting on a switching mechanism does not exceed a predetermined value - Google Patents

Abstract

A system for ensuring that the total force acting on the gear shifting mechanism (3) does not exceed a predetermined value. The force transferred from the gear lever (16) to the gear shifting mechanism receives power assistance from an assistance system, wherein the system is characterised in that the power assistance from the assistance system has a value that holds the total force acting on the gear shifting mechanism constant or reduces the total force acting on the gear shifting mechanism, when the gear shifting force is equal to or greater than a (second) limit value.

Description

25 30 35 528 347 gearbox, while maintaining the desired maneuvering forces as much as possible.

One solution to the problem of limiting the forces acting on the shift mechanism is to introduce a limitation on the force contribution supplied from the auxiliary system. Thus, in servo-operated systems, a limitation of the maximum force supplied from the servo mechanism is introduced. In electronically controlled, servo-operated systems, this can be achieved by introducing a reduction of the servo-operation, when the calculated total force on the shift mechanism in the gearbox exceeds a predetermined value. This is done, for example, in software.

However, it is an object of the present invention to provide a mechanical solution to the above-mentioned problems, which is independent of whether a mechanically or electrically controlled servo assistance system is used.

An approach to solve this problem is to create a condition-driven limitation in the power supply of the auxiliary system, insofar as the controlling conditions for limiting the power supply are made dependent on parameters such as the strength limit of the shift mechanism, etc. This can be solved by introducing a reducer which can work together with the servomechanism and which is capable of effecting a changed power supply into the servomechanism.

The objects of the invention are achieved by means of the invention as stated in the independent claims, wherein embodiments of the invention are stated in the dependent claims of the claim set.

According to the independent claim 1, a system is provided for ensuring that the total force acting on the shift mechanism does not exceed a predetermined value. In this context, it is assumed that the force transmitted from the shift lever to the shift mechanism receives a force contribution from an auxiliary system.

The force contribution from the auxiliary system has a value that keeps the total force acting on the shift mechanism constant or reduces the total force acting on the shift mechanism when the shift lever force is equal to or greater than a limit value (hereinafter referred to as the second limit value). The limit value is regulated depending on the strength of the shift mechanism to be used and on the other individual properties of the system. In case the invention is to be used in a shifting system where large forces are required to effect a change of the gear ratio, an auxiliary system is used which provides a force contribution which makes it easier for the driver to shift, typically such a called servo system. The system according to the invention, as stated in independent claim 2, will then have a dual function there - the force contribution from the auxiliary system has a value which increases the total force acting on the shift mechanism, when the force from the shift lever is increased within an area where the shift lever force is equal to or greater than a first limit value and less than a second limit value, and there - the force contribution from the auxiliary system has a value which keeps the total force acting on the shift mechanism constant or reduces the total force acting on the shift mechanism, when the gear lever force is equal as or greater than the other limit value.

The system can also be regulated by setting the limit values for the total force acting on the shift mechanism.

To describe the power transmission that takes place in the shifting system between the shift lever mechanism and preferably the shift mechanism and the auxiliary system, the term signal transmission is used hereinafter. By signal transmission is meant here the transmission of information about which input conditions apply to the shift mechanism and the auxiliary system. The signal transmitted between the shift lever mechanism and preferably the shift mechanism and the auxiliary system can thus be of different types. It can be a combined force and movement signal via struts or cable, for example in case the shifting system is mechanical.

The signal transmission can also be performed as a pressure signal, for example when the shifting system consists of a hydraulic system. The pressure signal transmission can of course also take place with pressure media other than hydraulic, for example pneumatic.

Alternatively, the signal transmission can be designed as an electrical, optical or electromagnetic signal. It should be mentioned that the same term signal transmission will also be used to describe the transmission of pressure, force and voltage ratios between other components of the system.

In the event that a force-giving device, for example a servo mechanism, is included in the auxiliary system, the signal is transmitted from the shift lever to the force-giving device, and depending on the value of the signal, a force contribution is transmitted to the shift mechanism. Alternatively, a signal may be transmitted from the auxiliary system, which represents a power contribution, to a power-providing device connected to the shift mechanism.

A signal corresponding to the signal from the gear lever, or derived from this signal, is transmitted to a reducer which is designed so that, depending on the value of the input signal, it can regulate the value of a power supply with which the reducer is connected. This can apply to power supplies of various kinds, such as pressurized fl uid, a source of voltage, etc. The reducer can transmit a power supply to the servomechanism or alternatively transmit a signal representing a power supply, for example in the case where the power supply is of the type that must be converted in order to be compatible with the servomechanism.

In a preferred embodiment of the reducer, this comprises at least one measuring unit and at least one regulator. The measuring unit receives the signal from the gear lever or the signal derived from the gear lever signal and controls the controller on the basis of this signal.

When the signal from the gear lever represents a value equal to or greater than the second limit value, the measuring unit controls the controller in such a way that the signal from the reducer to the servo mechanism is or represents a reduced power supply.

When the signal from the shift lever represents a value which is less than the second limit value but greater than or equal to the first limit value, the signal transmitted to the servomechanism from the reducer represents the power supply which the regulator receives from a source. When the signal from the shift lever represents a value equal to or greater than the second limit value, the power supply from the source in the controller is reduced, and the value of the signal transmitted to the servo mechanism from the reducer is reduced accordingly.

In an embodiment of the invention, the power supply can be provided by a pressurized unit, the regulator being formed with an inlet for directing the pressurized unit from the source to a cavity in the regulator. A prestressed control piston is arranged in the heel tube, which is designed with a borehole for guiding the till uidet to an outlet. Furthermore, the piston opens a drain by moving in the direction of its biasing force. When the signal from the gear lever represents a value which is less than the second limit value, the pressure from the outlet is substantially equal to the pressure of the supply supplied to the regulator. When the signal from the gear lever represents a value equal to or greater than the second limit value, the drain in the regulator is opened for discharge of fl uidum from the regulator, the pressure of the fl uidum being discharged from the outlet thus being reduced in compliance with the value of the signal from the gear lever.

According to a further embodiment, when the signal from the gear lever represents a value equal to or greater than the second limit value, the measuring unit controls the controller in such a way that a force is produced in the controller which counteracts / is greater than the control piston bias, and possibly the supply voltage to the valve seat of the control piston which closes the outlet, so that the piston thereby opens for discharge of fl uidum through the outlet. The power generated in the controller can be achieved in different ways, and also the control unit's control of the controller can take place in different ways.

In an implementation of the invention, the measuring unit comprises two prestressed pistons, which are arranged in the cavities of the measuring unit. The piston rod of the first piston is placed in a through-bore, which extends through the second piston and the piston rod of the second piston.

When the signal from the gear lever represents a value equal to or greater than the other limit value, a force is generated against one of the two pistons which counteracts / is greater than the sum of the pre-tension of the current piston, the pretension of the control piston and possibly the valve seat bias. In this case, the piston of the measuring unit is first displaced to abut against the control piston, which is also displaced in such a way that the outlet is opened.

In the case where the reducer with measuring unit, as described in the previous section, is used in a hydraulic shifting system, the force exerted against one of the two pistons will be generated by supplying fl uidum to the measuring unit as a result of the shifting lever force. When moving the gear lever in one direction, fl uidum is transferred to the measuring unit so that pressure is exerted against the piston surface of the first piston. When the gear lever is moved in the second direction, the fl uidum is transferred to a space between the first and the second piston in the measuring unit, so that the fl uidum exerts pressure against the piston surface of the second piston.

In the case where the reducer is used in a mechanical changeover system, the reducer in a preferred embodiment may comprise two controllers and a measuring unit which are placed between the two controllers. The measuring unit then comprises two pre-tensioned slides which are placed in a cavity in the measuring unit. force is exerted against one of the two slides, which is greater than the sum of the preload to the current slide, the preload to a valve arranged in the cavity of the measuring unit, the preload of the current control piston and possibly the preload on the valve seat of the control piston. In this case, an opening of the outlet is achieved and subsequent pressure regulation of the power supply into the servomechanism.

In the following, the conditions for the invention as well as a description of the function and two embodiments of the invention will be explained with reference to the accompanying figures, in which Fig. 1 shows the forces which arise in the shift mechanism according to the prior art.

F ig. 2 shows the forces which arise in the shift mechanism according to the solution principle on which the invention is based.

Fig. 3 shows a block diagram of the solution principle according to the invention.

Fig. 4 shows the invention used in a hydraulic shifting system.

Fig. 5 shows a reducer used in the system of Fig. 4.

Figs. 6, 7 and 8 show the invention utilized in a mechanical shifting system.

In Fig. 1, the horizontal axis shows the force exerted by the driver on the gear lever.

The vertical axis shows the force applied to the shift mechanism. A standard system without power contribution from an auxiliary system will provide a force on the gear selection mechanism in the gearbox as a function of the driver's force on the gear lever.

This relationship is shown by curve 2, which shows that the force acting on the gear selection mechanism increases in proportion to the driver's force on the gear lever.

Curve 5 shows an example of how the power contribution from auxiliary systems affects. At low gear levers, the force contribution from the auxiliary system will increase as a function of the gear lever forces and when the maximum force contribution from the auxiliary system has been reached, the curve will flatten and give a constant additional force to the gear selection mechanism in the gearbox.

The total force acting on the gear selection mechanism in the gearbox is shown in curve 6.

This curve is the result of the gear lever force shown in curve 2 and the power contribution from the auxiliary system shown in curve 5.

Curve 1 shows the maximum force that the gearbox synchronizing rings can withstand. For gear lever forces greater than the force value at the point where curve 6 10 15 20 25 30 35 intersects curve 1, there is a risk of overloading the gearbox synchronization mechanism.

This area is marked 7 in Fig. 1.

In order to avoid that the resultant, shown in curve 6, exceeds the maximum strength value of the shifting mechanism / synchronizing mechanism, the present invention has as a starting point to provide a system which by appropriate means ensures that the total force acting on the shifting mechanism is kept below the maximum strength value.

A solution principle for such a system is shown in Fig. 2. The horizontal axis shows the force exerted by the driver on the gear lever. The vertical axis shows the force applied to the shift mechanism. Curve 2 shows, in the same way as Fig. 1, a standard system without power contribution from any auxiliary system, which will give a force on the gear selection mechanism in the gearbox as a function of the driver's force on the gear lever.

Curve 3 shows an example of a solution in which a desired protection against overload of the shifting mechanism is introduced, by regulating the power contribution from an auxiliary system. As curve 3 shows, this is done by reducing the force contribution from the auxiliary system when the gear lever force reaches a certain limit value. With this solution principle, it is achieved that the shift mechanism is loaded with the resultant (shown by curve 4), by the shift lever force (shown by curve 2) and the force contribution from the auxiliary system (shown by curve). Fig. 2 shows that at low gear lever forces, the force contribution from the auxiliary system will increase as a function of the gear lever forces. At a certain limit value, whether this is a limit value for the gear lever force, or a limit value for the total force on the shift mechanism, the force contribution from the auxiliary system will be reduced with increasing gear lever force, so that the total force on the shift mechanism never exceeds the maximum force.

The maximum permissible total force on the shift mechanism is shown by curve 1.

Fig. 2 thus shows that the force contribution from the auxiliary system has a magnitude that increases the total force acting on the shift mechanism, when the shift lever force is increased within an area where the shift lever force is equal to or greater than a first limit value and less than a second limit value. Furthermore, the force contribution from the auxiliary system has a magnitude that keeps the total force acting on the shift mechanism constant, or reduces the total force acting on the shift mechanism, when the shift lever force is equal to or greater than the second limit value. 10 15 20 25 30 35 528 347 The value of the maximum total force allowed on the shift mechanism, as well as the first and second limit values, may vary depending on the type of system used. In the example shown in Pig. 1, the second limit value of the gear lever force will be located in the area where the force contribution from the auxiliary system is seen to have a reducing effect (see curve 2) on the total force shown by curve 4. The first limit value of the gear lever force will further be less than the second limit value, and in the example shown in Fig. 2, the first limit value will be located in the area where the power contribution of the auxiliary system (curve 2) begins to make a positive contribution to the total force on the shift mechanism (curve 4).

Fig. 2 shows that if the shifting force is further increased beyond the area where the auxiliary system provides a force contribution, the increase in shifting force will gradually lead to the maximum permissible force of the shifting mechanism (curve 1) being exceeded.

For safety reasons, it may in some cases be desirable to arrange the system in such a way that it is possible for the driver to change the gear ratio at such high shifting forces, even if the high shift lever force then exceeds the maximum permissible force of the shifting mechanism. shall be destroyed.

Fig. 3 shows a functional description of the system in accordance with the invention in the form of a block diagram.

Arrow 6a illustrates the force that the driver applies to the gear lever. The shift mechanism transmits the driver's power load on the shift lever to a signal 6b. The signal 6b can consist of a combined force and movement via struts or cable or the like.

It may be a hydraulic or pneumatic pressure or an electrical signal.

In most cases, the signal from the gear lever mechanism will affect the gear shift mechanism 3 directly at signal 6c. In the case shown, a servo assistance is included in the auxiliary system, the signal from the gear lever mechanism controlling a servomechanism 2. The servomechanism provides a power contribution indicated as signal 2a to the gearbox shifting mechanism. The signal 2a and the signal 6c constitute the total force of the shift mechanism in the gearbox. The servomechanism 2 receives a signal 5b which is or represents a power supply. The signal 5b can be, for example, a pneumatic or hydraulic pressure, or alternatively a voltage supply signal.

The auxiliary system further comprises a reducer, which is shown inside the marked field 1. The reducer comprises a regulator 5 and a measuring unit 4, which receives the desired switching force signal from the gear lever mechanism via the signal 6b. The measuring unit 4 controls the regulator 5, which is arranged in such a way that a power supply Sa can be regulated to the desired level Sb depending on the input signal 6b to the measuring unit 4. A power source provides the power supply 5a, the power source being for example air pressure supply, hydraulic pressure supply , power supply, etc.

In case the signal 6b is greater than or equal to the first limit value, the power supply 5b supplied to the servomechanism 2 will substantially correspond to the power supply Sa in to the controller. Under these conditions, the servo mechanism contributes a force contribution that increases the total force on the shift mechanism, which makes it easier for the driver of the vehicle to change gears. In case the signal 6b is equal to or exceeds the second limit value, the measuring unit 4 will control the controller so that the power supply 5a into the controller is regulated down into the controller, whereby a reduced power supply 5b into the servomechanism is achieved. This ensures that the force contribution 2a from the servo mechanism to the shift mechanism is limited when the force on the shift lever is greater than the second limit value. This ensures that the total force on the shift mechanism is kept smaller or equal to a predetermined size, so that a possible overload of the shift mechanism is avoided.

The solution principle illustrated in Fig. 3 is implemented in Fig. 4 in a hydraulic shifting system with pneumatic servo assistance. The example shown in Fig. 4 shows the reducer 1 made with a regulator part 5 - shown here as a pneumatic pressure reducing valve 5 - which is controlled by a hydraulic measuring unit 4. Other types of fluid medium can of course also be used as pressure medium in the regulator and for that part also in the measuring unit. The detailed embodiment of the reducer is most clearly shown in Fig. 5. This embodiment of the solution principle will be described in the following with reference to both Fig. 4 and Fig. 5.

The measuring unit 4 comprises a cavity 12 formed in the reducer 1, wherein in the cavity 12 a first prestressed piston 13 and a second preloaded piston 14 are arranged. Figs. 4 10 15 20 25 30 52 52 54 54 is arranged with its piston rod extending through a borehole in the second piston 14, so that the ends of the piston rods of the two pistons are positioned at a corresponding distance from the regulator piston 15. By Pig. 4 and 5 it further appears that the first and the second piston 13, 14 are biased with springs 13a, 14a.

When carrying out gear changes, hydraulic fluid is transferred through transfer lines to the servo mechanism 2 and to the measuring unit 4. In this embodiment, the servo mechanism 2 comprises a valve unit and a servo actuator. If the gear lever is moved in the direction of the arrow A, hydraulic fluid is transferred through the lines 10 to the servomechanism 2 and to the area of the cavity which is above the piston surface 13b of the piston. If the gear lever is moved in the direction of the arrow B, hydraulic fluid is transferred through the lines 11 to the servomechanism 2 and to the area overlying the piston surface 14b of the second piston 14.

The pressure acting on the respective piston surfaces in each of the two cases depends on the force exerted by the driver on the gear lever. In order to achieve displacement of one or the other piston, the force acting on the pistons 13 and 14 must have a magnitude and direction which can overcome the biasing force exerted by the springs 13a and 14a.

If the force exerted on the piston surfaces 13b, 14b is less than the second limit value, sufficient movement of the respective pistons in the reducer is not achieved for the valve seat 19 of the regulator piston to be opened. A flow path is established from a source 16 to the valve assembly connected to the servo mechanism. Pressurized fluid is passed from the source 16 into an inlet 16a of the regulator and further through a borehole 17 formed in the regulator piston 15, out through an outlet 21 and further into the valve unit. In this case it is achieved that the servomechanism is supplied with a pressure substantially corresponding to the pressure at the source in the source 16. The pressure supply from the reducer 1 to the servomechanism 2 determines the force contribution from the servomechanism to the shift mechanism 3. In this case the pressure supply to the servomechanism 2 force acting on the shift mechanism 3.

In the regulator part 5 the control piston 15 is shown biased with spring 15a. If the force acting on one of the pistons 13, 14 is greater than the other limit value, it is achieved that the end of the associated piston rod is brought into abutment against the regulating piston 15. The piston 13 or 14 in this case transmits a force to the regulating piston 15, which counteracts 10 15 20 25 30 35 528 347 11 regulator piston 15. The regulator piston 15 is then moved downwards to abut against the valve seat 19 of the regulator piston, which is prestressed by means of a spring 19a, at the same time as the force is sufficient to counteract the prestressing of the spring 19a, so that the spring is compressed. This opens the valve seat 19 of the regulator piston, which results in a discharge of fl uidum to the drain 20. How large an opening is achieved when the valve seat 19 of the regulator piston is opened, and thus how much fl uidum is discharged through the fl uidum path between the source and the valve unit, thus depends on the force acting on piston surfaces l3b or l4b. The greater the force exerted by the driver on the gear lever, the greater the force acting on the piston surfaces 13b or 14b, whereby also greater draining of fl uidum through the drain 20 is achieved. and a power contribution from the servo mechanism which ensures that the total force acting on the shift mechanism is kept below a predetermined value.

In Figs. 6-8, the solution principle as in Fig. 3 is implemented in a mechanical shifting system with pneumatic servo assistance. Fig. 6 shows an overview of the mechanical shifting system. By mechanical shifting system is meant here cable or stay transfer between gear lever and gearbox. F ig. 7 and 8 show a reducer 1a to be used in such a mechanical shifting system. The reducer 1a comprises a measuring unit 4, which is placed between two controllers 5a and 5b. The measuring unit of the reducer in this case consists of a servo valve. However, the servo actuator is located outside the reducer in the same way as in the embodiment according to Figs. 4-5. For the sake of simplicity, the following term servo mechanism 2 is used about the servo actuator.

The controllers Sa, 5b are substantially similar to the controller shown in Figs. 4 and 5.

Therefore, the same reference numerals are used to a large extent as on the controller in Fig. 4. It is seen that the measuring unit 4 "has a different construction than the measuring unit shown in Fig. 22a, 22b, which are biased by springs 22c and 22d. The power from the shift lever is transmitted to the servomechanism 2 and the reducer 1a by means of a balanced lever (not shown). The lever has its point of attack in the measuring unit 4 'of the reducer by means of an activating pin 12, which exerts a force on one or the other slide. Depending on whether the shift lever is moved in a direction corresponding to A and B, as shown in Fig. 4, this force will either act on the slide 22a or 22b. The descriptions of mode of operation and construction thus become the same for both sides of the reducer. 10 15 20 25 30 35 528 347 12 If the system is not active, fl uidum (air) is led from the source in the regulator part through the inlet l6a, 16b. The outlet 21a, 21b leads to the side of the servomechanism 2 which, when the pressure increases, will move the actuator in the same direction as the force from the gear lever determines. Drains 20 and 24 are used to let air out of the system.

In this case, the outlet 21a, 21b for transferring pressurized air to the servomechanism 2 is directly connected to the drain 24 via the drain valve seat 26 and a borehole 25 inside the slide 22a, 22b. The system, as shown in Figs. 7 and 8, is shown in its unloaded state.

When the gear lever force is equal to or greater than the first limit value, but less than the second limit value, the measuring unit is activated by the activating pin 12 exerting a force which presses on one of the slides 22a, 22b and moves it down a distance, so that the spring 22c, 22d, which provides bias for the slide 22a, 22b, is compressed to some extent. It should be mentioned here again that the force required to surface the slide constitutes a function of fi stiffness and dry fl stretching distance. When the slide 22a, 22b has been moved a distance, the drain valve seat 26 will seal against the valve 27. This means that the outlet 21 of the servomechanism 2 is no longer vented to drain 24. Thus, further to move the slide will also surface the valve 27, which eats compresses 28 and opens for passage of fluid through the supply valve seat 29. The fluid from the source will be introduced through the inlet 16a, 16b, through the borehole 17 in the regulator piston 15, then through the channel 23 and thus into the supply valve seat 29 - via grooves in the valve seat 30 - if the valve seat 30 abuts the regulator piston 15. These grooves are not shown in the sketch.

The flow passage which occurs by moving the valve 27 in the direction of the supply valve seat 29 is made possible either by the possibility of moving the valve 27 relative to a pin 31 housed in a recess in the valve 27 and the control piston 15, or by the valve 27 and the pin 31, the valve 27, the connecting pin 31 and the regulator piston 15 are moved downwards relative to the control piston 15. Alternatively, the distance between the regulator piston seat seat 19 and the regulator piston 15 makes this possible without leading to the regulator piston valve seat 19 being opened. The fluid will thus flow out to the servomechanism 2 and cause the driver to be able to move it more easily. When the servomechanism 2 moves towards the position indicated by the gear lever, the distance between the desired position (gear lever) and the actual position (servomechanism 2) will decrease, whereby the lever mechanism, which connects the regulator to the servomechanism 2, will ensure that as the desired position is reached to move the slide 22a, 22b back to the original position. Thus, the described valve mechanism will act as a position regulator.

The regulator piston 15 can be activated by the pin 31 which is accommodated in the bore in the valve 27, whereby the pin 31 can optionally also be attached to the valve. The pin 31 is not fixed in the regulator piston 15 but can be moved independently thereof.

As also mentioned above, the valve 27 moves due to the fact that the force exerted on the gear lever represents a counter force greater than the bias of the slide spring 22c, 22d.

Furthermore, the upper part of the control piston 15 will be provided with pressurized fluid via the channel 23. The supply from the source, which is introduced through the inlet 16a, 16b, enters the regulator piston 15 into a cavity between two sliding seals, as shown in Fig. 6 and 7. The net force from the supply from the source to the control piston 15 is almost zero. The underside of the large piston surface in the control piston 15 is vented to drain 20 via duct 32, so that no pressure build-up occurs there.

The sum of the forces from the gear lever transmitted through the actuating pin 12 and the force component from the pressure in the channel 23 towards the top of the regulator piston 15, strives to press the regulator piston 15 downwards and in this way compress the spring 15a. At a certain force from the gear lever mechanism, depending on the spring stiffness of the slide spring 22c or 22d + the valve spring 28 + the spring 15a of the regulator piston, the regulator piston 15 will be mounted against the regulator piston valve seat 19 and thus close to supply from the source through the inlet 16a, 16b.

If the driver stops the shifting of the gear lever there, the servomechanism 2 will use air from the outlet 21a or 21b, whereby the air pressure over the control piston 15 will drop and the piston is pushed back by the spring 15a until the control piston 15 eases from the regulator piston valve seat 19 and lets air in again. the measuring unit / servo valve. (The same applies to the embodiment shown in Figs. 4 and 5.) 10 15 20 25 30 528 347 14 If, on the other hand, the driver tries to increase the force on the gear lever further, so that the gear lever force becomes equal to or greater than the changed limit value, the regulator part is activated 5 to achieve a down-regulation of the pressure the fl uidum introduced into the servomechanism 2. In this case the regulator piston 15 is still pushed further down, whereby the valve seat 19 of the regulator piston is pressed downwards by compressing the spring 19a _. The fluid introduced into the servo valve / measuring unit 4 "through the channel 23 will then be vented to the drain 20. A balance between the pressure on the top of the regulator piston 15, the force applied by the driver to the gear lever mechanism transmitted by the actuating pin 12, and the counter force from the spring to the regulator piston 15, so that the unit pin 31, the regulator piston 15, the spring of the regulator piston 15, the regulator piston seat 19 and the associated spring 19 together act as a pressure regulator, which regulates the maintenance pressure to be delivered to the servo valve / measuring unit 4 ”. When draining fl uidum through the drain 20 and the consequent reduced pressure on fl uidum which is then led to the servomechanism 2 through the outlet 2la, 2lb, it is achieved that the total force acting on the shift mechanism is kept constant or reduced.

The pressure control of the id uidet delivered to the mains unit / servo valve and thence to the servo mechanism 2 is so adapted that when the force exerted by the driver on the gear mechanism increases beyond an initial deadband, the pressure of the in uidet into the servo valve will decrease proportionally. This means that the greater the force the driver shifts with, the less servo gain the servo valve will contribute, when the shift lever force exceeds the second limit value. This will continue until the servo unit is no longer able to make any power contribution.

Thus, the total force acting on the shift mechanism from the servomechanism 2 and the shift lever force will be prevented from exceeding the predetermined maximum value.

Of course, in order to provide the bias for the various pistons used in the reducer 1 and 1a, means other than springs can also be used.

Claims (13)

1. 0 15 20 25 30 35 528 347 15 PATENT REQUIREMENTS 1. A system for ensuring that the total force acting on a shift mechanism (3) does not exceed a predetermined value, the force transmitted from the shift lever to the shift mechanism (3) receiving a force contribution from an auxiliary system, characterized in that a (second) limit value is used to control that the force contribution from the auxiliary system is reduced, when the gear lever force is increased, whereby - the force contribution from the auxiliary system has a value which keeps the total force acting on the shift mechanism (3) constant or reduces the total force acting on the shift mechanism ( 3), when the gear lever force is increased within an area where the gear lever force is equal to or greater than said (second) limit value. System according to claim 1, characterized in that a first limit value is used to control that the force contribution from the auxiliary system increases, when the gear lever force is increased, wherein - the force contribution from the auxiliary system has a value which increases the total force acting on the shift mechanism (3 ), when the gear lever force is increased within an area where the gear lever force is equal to or greater than the first limit value but less than the second limit value. . System according to claim 1 or 2, characterized in that the force from the gear lever is transmitted as a signal (6c) to the shift mechanism (3) and that the force exerted by the driver on the gear lever is transmitted as a signal (6b) from the gear lever to the auxiliary system. System according to claim 3, characterized in that the signals transmitted are hydraulic, pneumatic, electrical, optical or electromagnetic. System according to one of Claims 3 or 4, characterized in that the signal (6b) from the gear lever to the auxiliary system is preferably transmitted to a power-giving device, for example a servo mechanism (2), and that a signal (2a) is transmitted, which is or represents a power contribution from the auxiliary system to the shift mechanism (3). System according to one of Claims 3 to 5, characterized in that a signal corresponding to the signal (6b) from the gear lever or derived from this signal (6b) is transmitted to a reducer (6b). 1), and that the reducer (1) transmits a signal which is or represents a power supply (5b) to the servomechanism (2). System according to claim 6, characterized by the reducer (1) comprising at least one measuring unit which receives the signal from the gear lever or the signal derived from the signal of the gear lever, at least one regulator which is controlled by the measuring unit and when the signal from the gear lever represents a value equal to greater than or greater than the second limit value, the measuring unit controls the controller so that the signal transmitted from the reducer to the servo mechanism is or represents a reduced power supply. System according to claim 7, characterized in that when the signal from the gear lever represents a value which is less than the second limit value, the signal transmitted to the servomechanism from the reducer represents the power supply which the controller receives from a source (Sa), when the signal from the gear lever represents a value equal to or greater than the second limit value, the power supply from the source (5a) in the regulator is reduced and the value of the signal transmitted to the servo mechanism from the reducer is reduced accordingly. System according to one of Claims 7 or 8, characterized in that the power supply is provided by a pressurized fluid and the regulator (5) is designed with an inlet for directing the pressurized fluid from the source (Sa) to a cavity in the regulator. , wherein in the cavity is arranged a prestressed regulator piston (15), which is formed with a borehole (17) for guiding the outlet to an outlet, wherein the piston can cause opening of a drain by moving in the direction of its pre-tensioning force, when the signal from the alternating lever represents a value less than the second limit value, the tryck uidet pressure out of the outlet is substantially the same as the pressure of the fl uidum supplied to the controller, when the signal from the gear lever represents a value equal to or greater than the second limit value, the drain is opened in the regulator for the discharge of fl uidum from the regulator and the pressure to fl uidum discharged from the outlet is reduced in accordance with the value of the signal from the xelspaken. 10. 15 20 25 30 35 10. 11. 12. System according to claim 9, characterized in that when the signal from the gear lever represents a value equal to or greater than the second limit value, the measuring unit (4) controls the regulator (5) so that a force is produced in the regulator (5) which counteracts the biasing force of the regulating piston (15), and possibly the pre-voltage to the valve seat of the regulating piston which closes to the drain, so that the regulating piston is thereby opened for discharge of fl uidum through the drain. System according to one of Claims 9 to 10, characterized in that the measuring unit (4) comprises two prestressed pistons (13, 14) arranged in the cavities of the measuring unit, the piston rod of the first piston being positioned in a continuous bore extending through the second piston. and the piston rod of the second piston, - when the signal from the gear lever represents a value equal to or greater than the second limit value, a force is exerted against one of the two pistons (13,14) which counteracts the sum of the bias of the current piston, the regulator piston (15) bias and possibly the bias to the valve seat of the regulator piston, the piston of the measuring unit being displaced to abut against the regulator piston for subsequent displacement of the regulator piston so that the drain is opened. System according to claim 11, characterized in that the reducer (1) is used in a hydraulic shifting system, where movement of the shift lever in one direction causes the transmission of fluid to the measuring unit (4) so that it exerts pressure against the first piston (13) piston surface (13b), and movement of the gear lever in the second direction causes the transfer of fl uidum to a space between the first and the second piston in the measuring unit, so that fl uidet exerts pressure against the piston surface (14b) of the second piston (14). System according to one of Claims 7 to 10, characterized in that the reducer (1) is used in a mechanical switching system and comprises two controllers (5a, 5b) and a measuring unit (4 ") which is placed between the two controllers (5a). 5b), wherein the measuring unit (4 ") comprises two prestressed slides (22a, 22b) which are placed in cavities in the measuring unit (4 °), so that movement of the gear lever with a force equal to or greater than the second limit value in one or the other direction causes a force to be exerted against one of the two slides (22a, 22b), this force being greater than the sum of the ear tension to the current slide, the preload to a valve arranged in the cavity in the measuring unit, the bias voltage to the current regulator piston (15), and possibly the bias voltage to the valve seat of the regulator piston (15), so that the drain is opened for discharge of fl uidum.