US20030155182A1

US20030155182A1 - Device and method for accurately supplying components of an automatic gearbox for motor vehicles

Info

Publication number: US20030155182A1
Application number: US10/332,357
Authority: US
Inventors: Bernhard Sich
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2000-07-07
Filing date: 2001-06-23
Publication date: 2003-08-21

Abstract

The device for accurately supplying components of an automatic gearbox for motor vehicles is characterized in that the supply line which supplies the gearbox with hydraulic oil is divided into two lines (1, 2), the first line (1) having an aperture (4) and a differential pressure valve (5) and the second line (2) having a pressure limiting valve (6).

Description

The present invention relates to a device designed to ensure a precisely targeted fluid supply to components of a vehicle automatic transmission, especially a friction-type transmission, and a corresponding method.

Continuously variable, friction-type transmissions are ordinarily equipped with input and output disks that are oriented coaxially to a common shaft and are arranged in pairs, the inner surfaces of which are toroidal in shape, along with friction gears that are positioned between the pairs of input and output disks. These friction gears are in frictional contact with both the input and the output disks, and transfer torque that is supplied to them by the input disks to the output disks via the frictional contact, wherein the speed of the friction gears is higher the greater the distance is between their point of contact with the input disk and the rotational axis. In contrast, the speed of the output disk is greater, the closer the point of contact, between the friction gear and the output disk, is to the rotational axis is. Hence, by swiveling the friction gears, the speed of the output disk is infinitely adjustable. To this end, the rotational axes of the friction gears are mounted on a carrier, which can be controlled via a swiveling device.

If this type of friction transmission is connected to an internal combustion engine of a vehicle, via a hydrodynamic converter or a wet running starting clutch, then the clutch will generate heat, during slip drive which must then be removed via a purposeful supply of hydraulic fluid.

However, the operating points for cooling the starting clutch and for cooling and lubricating the remaining transmission components—in other words the bearing and the teething—are very different, so that the hydraulic fluid which is available and supplied to the automatic transmission must be supplied in varying quantities to the starting clutch and to the remaining components of the transmission.

The object of the present invention is to disclose a device and a method with which lubricating fluid can be optimally and precisely supplied to the components of an automatic transmission, especially a friction-type transmission, wherein, compared with traditional devices and/or methods, a substantially lower overall quantity of hydraulic fluid is required.

Proceeding from a device of the type described in detail above, this object is attained with the features specified in the characterizing section of claim 1; advantageous designs are described in the sub-claims; the method specified in the invention is outlined in greater detail in the independent method claim.

The device designed, according to the invention, for a precisely targeted supply to components in an automatic vehicle transmission thus provides that the feed line that supplies the transmission with hydraulic fluid is separated into two lines; one line is equipped with a restrictor and a differential pressure valve oriented in the direction of flow, while the other is equipped with a pressure relief valve.

The differential pressure valve is advantageously connected to an electric pressure controller, which itself is connected to the electronic transmission control system; in another advantageous exemplary design, the pressure relief valve is also connected to the electric pressure controller.

According to the method specified in the invention for the precisely targeted supply to components in an automatic transmission, especially a friction-type transmission for a vehicle, the hydraulic fluid that is supplied to the transmission for the purpose of lubricating and cooling is separated in two lines into two sub-quantities. In the first line, the rate of flow is controlled via a restrictor and a differential pressure valve, both of which are installed within this line, while in the second line, the pressure in the first line prior to the restrictor is controlled via a pressure relief valve installed within this second line. The differential pressure valve in the first line regulates the differential pressure at the restrictor that is installed in the same line. By precisely regulating the differential pressure valve, via a control valve in the form of an electric pressure controller which itself is connected to the electronic transmission control system, the flow rate can be controlled in the first line that is equipped with the restrictor and the differential pressure valve. The remaining hydraulic fluid flows through the second line and is fed to the transmission components, for example, to the bearings.

The advantage of the device specified in the invention is that the quantity of hydraulic fluid that is required for purposes of cooling and lubrication can be substantially reduced, allowing a savings of about 50% over traditional automatic transmissions. The precise control of the amount of hydraulic fluid in the first line, which is equipped with the restrictor and the differential pressure valve, enables the control and maintenance of a predetermined temperature of some heat-producing points in the automatic transmission, especially the starting clutch. Despite a decrease in hydraulic power—in other words the losses that occur in an automatic transmission—the advantage of reduced power consumption by the hydraulic fluid used for lubricating purposes is still achieved. The resolution and hysteresis of the characteristic flow rate curve also more advantageously compares with that of a traditional automatic transmission.

Below, the invention will be described in greater detail with reference to the attached diagrams, in which two advantageous exemplary designs of a device as specified in the invention are schematically illustrated. These show: [0011]
FIG. 1 is a first hydraulic fluid cycle, and [0012]
FIG. 2 is a second hydraulic fluid cycle, according to the invention.[0013]
In the diagrams, similar components are designated with the same reference numbers. A feed line for hydraulic fluid in an automatic transmission, which in this case is a friction-type transmission, is designated with the [0014] numeral 3. The feed line 3 is divided into two lines 1, 2 for a precisely targeted supply to the components of the automatic transmission, which require different operating points for cooling and/or lubrication. To this end, a restrictor 4 and a differential pressure valve 5 are installed in the first line 1, while a pressure relief valve 6 is installed in the second line 2.
The [0015] differential pressure valve 5, in the first line 1, is connected to an electric pressure controller 7, which is itself connected to the electronic transmission control system 8, by which it is controlled in keeping with the required operating parameters.
In the exemplary design illustrated in FIG. 2, the [0016] pressure relief valve 6 in the second line, is also connected, via the dashed line 9, to the electric pressure controller 7 and thus to the electronic transmission control system 8.
Thus, with the arrangement described, the hydraulic fluid required by the automatic transmission is divided into two sub-quantities and is fed through the [0017] lines 1 and 2, wherein in the first line 1 the flow rate can be precisely controlled via the restrictor 4 and the differential pressure valve 5. In this process, the differential pressure valve 5 generates a differential pressure at the restrictor 4, wherein the differential pressure valve 5 is controlled via the electronic transmission control system 8 and the electric pressure controller 7. This enables a precise control of the flow rate in the line 1, which is connected to the heat-generating starting clutch of the friction-type transmission.
The remaining hydraulic fluid flows through [0018] line 2 and serves to lubricate the bearing and/or the teething, wherein the pressure relief valve 6, provided in the second line 2, controls the pressure prior to the restrictor 4. If the pressure relief valve 6 is also controlled by the electric pressure controller 7, and thus by the electronic transmission control system 8, via the line 9 as shown in FIG. 2, then the pressure in the first line 1 can also be controlled prior to the restrictor.
The precise control of the quantity of hydraulic fluid in the [0019] first line 1 for the purpose of regulating a preset temperature at heat-generating points in the automatic transmission makes it possible to reduce the overall quantity of hydraulic fluid required by the transmission by approximately 50%. Lower power consumption in the generation of lubricating pressure also results.

REFERENCE FIGURES



Reference FIGS.

	1	Line
	2	Line
	3	Feed Line
	4	Restrictor
	5	Differential Pressure Valve
	6	Pressure Relief Valve
	7	Electric Pressure Controller
	8	Electronic Transmission Control System
	9	Line

Claims

1. Device for the precisely targeted supply to components in an automatic vehicle transmission, characterized in that feed line (3) that supplies the transmission with hydraulic fluid is divided into two lines (1, 2), wherein a restrictor (4) and a differential pressure valve,(5) are installed in the first line (1), and a pressure relief valve (6) is installed in the second line (2).

2. Device according to claim 1, characterized in that the differential pressure valve is connected to an electric pressure controller (7), which is connected to the electronic transmission control system (8).

3. Device according to claims 1 and 2, characterized in that the pressure relief valve is connected to the electric pressure controller (7).

4. Method for the precisely targeted supply to components in an automatic vehicle transmission, characterized in that the hydraulic fluid that is supplied to the transmission via a feed line for the purpose of lubricating and cooling is divided into two sub-quantities, which flow through two separate lines, wherein in the first line the flow rate of the hydraulic fluid is controlled via a restrictor and a differential pressure valve, which is controlled by an electric pressure controller, which itself is controlled by the electronic transmission control system, while the pressure prior to the restrictor in the first line is controlled via a pressure relief valve installed in the second line, which also is controlled by the electric pressure controller and thus by the electronic transmission control system.