Method for controlling an automated transmission

Abstract

A method of controlling an automated transmission with positioning cylinders (6, 8, 20) controlled by shift valves or venting valves (10, 12, 16, 18, 22, 24). At least one cut-off valve (4) is positioned in front of the shift or venting valves and a control device controls the valves while pressure pipes, which follow the cut-off valve (4), are connected with one another following the cut-off valve (4). Due to the fact that the cut-off valve (4), for reasons of design simplicity and cost, is generally designed as a simple 2/2 way valve which only allows pressure increase but not pressure reduction, the method provides control of the shift valves or ventilation or venting valves (16, 18), of a non activated positioning cylinder (8), so that the pressure pipe system is connected with an outflow pipe (14) for a pressure reduction in the pressure pipe system (30, 32, 34).

Claims

1. A method of controlling an automated transmission comprising: a first positioning cylinder (6) being a dual functioning positioning cylinder having a pair of 3/2 valves (10, 12); a second positioning cylinder (8) being a single functioning positioning cylinder and having first and second 2/2 valves, and the first 2/2 valve (16) facilitates filling of the second positioning cylinder (8) and the second 2/2 valve (18) facilitates venting of the second positioning cylinder (8); a third positioning cylinder (20) being a single functioning positioning cylinder, configured to actuate a clutch and having a third and fourth 2/2 valves, and the third 2/2 valve (22) facilitates filling of the third positioning cylinder (20) and the fourth 2/2 valve (24) facilitates venting of the third positioning cylinder (20); at least one main cut-off valve (4) being positioned upstream of the 2/2 and the 3/2 valves (10, 12, 16, 18, 22, 24), and a control device for controlling the 2/2 and 3/2 valves, the method comprising the steps of: connecting a plurality of pressure pipes with one another to facilitate a pressure reduction in a pressure pipe system (30, 32, 34) which follows the at least one main cut-off valve (4), and controlling the 2/2 and the 3/2 valves so that the pressure pipe system is vented via a pressure outflow pipe (14) for facilitating the pressure reduction in the pressure pipe system.

2. The method according to claim 1, further comprising: providing the transmission with at least a transmission brake which is activated by the second functioning positioning cylinder (8), filling the second functioning positioning cylinder (8) via the first 2/2 valve (16) and venting the second functioning positioning cylinder (8) via the second 2/2 valve (18), and switching each of the first 2/2 valve (16) and the second 2/2 valve (18) into a position which facilitates the pressure reduction without actuating the second positioning cylinder (8).

3. A method of controlling an automated transmission comprising: a plurality of pressure pipes; a pressure outflow pipe; a first positioning cylinder being a dual functioning positioning cylinder having a pair of 3/2 valves; a second positioning cylinder being a single functioning positioning cylinder, configured to act as a transmission brake and having first and second 2/2 valves, and the first 2/2 valve facilitates filling of the second positioning cylinder and the second 2/2 valve facilitates venting of the second positioning cylinder; a third positioning cylinder being a single functioning positioning cylinder, configured to actuate a clutch, and having third and fourth 2/2 valves, and the third 2/2 valve facilitates filling of the third positioning cylinder and the fourth 2/2 valve facilitates venting the third positioning cylinder; at least one main cut-off valve being positioned upstream of the 2/2 and 3/2 valves; a pressure sensor located downstream from the at least one cut-off valve for measuring a system pressure; a check valve located upstream from the third positioning cylinder to avoid venting of the third positioning cylinder in response to a drop in the system pressure; and a control device in communication with the pressure sensor for controlling the pairs of 3/2 valves, the first, the second, the third and the fourth 2/2 valves; wherein when the pressure sensor indicates a need to lower the system pressure in the plurality of pressure pipes, the control device switches the first 2/2 valve and the second 2/2 valve into a position such that the system pressure is vented, via the pressure outflow pipe, while the second positioning cylinder is not actuated to lower the system pressure to a desired system pressure.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The description has a drawing attached to it for a further explanation of the invention. It shows schematically a shift scheme for the execution of the inventive control method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(2) The shift system, which is presented in the drawings as a pneumatic shift system for shifting an automated shift transmission for commercial vehicles for instance, is supplied with a pressure means by a pressure means supply system which is part of the vehicle, and which has a pressure means supply container 2.

(3) In the present exemplary case, the shift system comprises of a pressure means supply container 2, followed by a main cut-off valve 4 which can connect or separate a following shifting configuration with the pressure means supply container 2. It is also noted here that several parallel positioned main cut-off valves can be provided, instead of the main cut-off valve 4.

(4) In the presented case, the following shifting configuration comprises two positioning cylinders 6 or 8, respectively, whereby the first positioning cylinder 6 is a dual-functioning positioning cylinder, for the selection of a gear step or a shifting path for instance, and the second positioning cylinder 8 is a single-side functioning positioning cylinder, for a transmission brake.

(5) The two pressure chambers 9 and 11 of the first positioning cylinder 6 are each filled by means of an assigned 3/2 way valve 10 or 12, respectively, or vented via a pressure or means outflow pipe 14, while the only pressure or chamber 13 of the second positioning cylinder 8 is filled by means of the 2/2 way valve 16 and is vented by means of a 2/2 way valve 18, via the pressure means outflow pipe 14. The 3/2 way valves 10 and 12 are also called shifting valves, and the 2/2 way valves 16 and 18 are also called ventilation and venting valves.

(6) Here, the shift system also comprises a third single-side functioning positioning cylinder 20 which serves for the actuation of a transmission clutch. The only pressure chamber 21, of the third positioning cylinder 20, is respectively filled or vented via a 2/2 way valve 22 and vented via a 2/2 way valve 24, by the pressure means outflow pipe 14.

(7) The 2/2 way valve 22 has a check valve 26 positioned in front of it for filling of the clutch positioning cylinder 20 to avoid venting of the clutch positioning cylinder 20, during a drop of the pressure supply.

(8) The 3/2 and 2/2 way valves 10, 12, 16, 18, 22, 24 and, in particular, the main cut-off valve 4, which are assigned to the positioning cylinders 6, 8, 20, are triggered via a control device which for clarity reasons, is not shown here. A pressure sensor 28, which follows after the main cut-off valve 4, collects the nominal pressure in the shifting configuration and feeds a respective signal to the control device.

(9) For instance, if the pressure in the pressure pipe system which is positioned after the man cut-off valves 4, meaning the interconnected pressure pipes 30, 32, 34, needs to be lowered, the ventilation and venting valves 16 and 18 are each preferably switched into a position, for a short time under the assumption that the transmission brake (positioning cylinder 8) is not activated, which allows a pressure flow rate such that the entire pressure pipe system is connected with the pressure means outflow pipe and is vented to a point where the desired pressure adjusts itself.

REFERENCE CHARACTERS

(10) 2 Pressure Means Supply Container 4 Main Cut-Off Valve 6 Positioning Cylinder 8 Positioning Cylinder 9 Pressure Chamber 10 3/2 Way Valve 11 Pressure Chamber 12 3/2 Way Valve 13 Pressure Chamber 14 Pressure Means Outflow Pipe 16 2/2 Way Valve 18 2/2 Way Valve 20 Positioning Cylinder 21 Pressure Chamber 22 2/2 Way Valve 24 2/2 Way Valve 26 Check Valve 28 Pressure Sensor 30 Pressure Pipe 32 Pressure Pipe 34 Pressure Pipe