FR2903460A1 - Hydraulic actuator for automatic or semi-automatic type gear box, has pressure and flow rate solenoid valves that are respectively proportional and binary and define flexible and fixed amplitude openings between two communication paths - Google Patents

Abstract

The actuator (13) has two pressure and flow rate solenoid valves (22, 23), where each valve is interposed between two pressure chambers (17, 18). The pressure solenoid valve is proportional and defines an flexible amplitude opening between two communication paths (22a, 22b, 22c, 23a, 23b, 23c), in two active and inactive states of the pressure solenoid valve. The flow rate solenoid valve is binary and defines an fixed amplitude opening between the two communication paths, in two active and inactive states of the flow rate solenoid valve.

Description

1 "Enhanced hydraulic actuator for a vehicle gearbox

  The invention relates to a hydraulic actuator for a transmission mechanism of a vehicle, particularly a motor vehicle, such as a semi-automatic or automatic gearbox.For this type of gearbox, a control unit 5 the hydraulic actuator to ensure the passage from one speed to another, depending on the choice of the driver when the gearbox is in semi-automatic mode, or according to a gear management system when this box In order to ensure the shifting function, the known actuator, indicated by 1 in FIG. 1, comprises a double-acting cylinder 2 defining two pressure chambers 3, 4 and a piston 6 displaceable in translation along a main direction A1, A'1 in two opposite directions.

  This actuator 1 is further provided with two three-way valves 11, 12, each interposed between a chamber 3, 4 of the jack, a pressurized source 7 and a recovery container 8; the three channels 11a, 11b, 11c and 12a, 12b, 12c respectively leading to the valves 11 and 12 respectively connecting these valves 11 and 12 to the source 7, the chamber 3, 4 and the container 8. Each three-way valve 11 , 12 can occupy an active state or an inactive state, in which the valve 11, 12 provides communication between two channels and isolates these channels from the third. More specifically, in its active state, each valve 11, 12 provides the connection between the chamber 3, 4 and the source 7 while isolating the chamber 3, 4 of the container 8, and in its inactive state, the valve 11, 12 connects the chamber 3, 4 to the container 8 and isolates this chamber 3, 4 2903460 2 from the source 7, the two valves 11, 12 occupying at each moment different states so as to allow movement of the piston 6 in two opposite directions. These two valves 11, 12 are further of proportional type and each allow, in their active and inactive states, a modulation of the quantities of fluid flowing between the two channels in communication, so as to ensure a gradual displacement of the piston 7 in the two opposite directions along the main axis Al, A'1.

However, the manufacturing and maintenance costs of this actuator are important and the invention aims to overcome this disadvantage. To this end, the invention relates to a hydraulic actuator comprising a double-acting jack provided with two pressure chambers and a piston displaceable in translation in a main direction in two opposite directions, a hydraulic power unit for the jack, a non-pressurized recovery vessel, and two three-way valves each interposed between a chamber, the hydraulic unit and the vessel, and each capable of occupying an active state, wherein the valve provides communication between the two ports respectively connected to the chamber and at the source and isolates this chamber from the container, and an inactive state, wherein the valve provides communication between the two channels respectively connected to the chamber and the container and isolates this chamber from the source, the two valves occupying each instant different states so as to allow a gradual displacement of the actuator 30 in two opposite directions. According to the invention, one of the valves is proportional and defines in its two states, between the two channels in communication, a modulable amplitude opening, the other valve is binary and defines a fixed amplitude opening 2903460 3 the two channels in communication. According to another characteristic, the proportional valve is of the pressure solenoid type, the amplitude of the opening being a function of the pressure of the fluid downstream of the valve. According to yet another characteristic, the proportional valve is of solenoid type in flow, the amplitude of the opening being a function of the flow of fluid downstream of the valve. The invention also relates to a gearbox of a motor vehicle comprising one of the actuators above and a control unit delivering a control current of the proportional valve of this actuator, the amplitude of the opening defined. by the valve being proportional to the control current. The invention will be better understood, and other features thereof will appear more clearly in the following description, with reference to the accompanying drawings given by way of example only, among which: FIG. 1 above is a diagram of FIG. principle of a hydraulic actuator of known type; FIG. 2 is a block diagram of an actuator according to the invention for a direction of positive displacement of the piston of the actuator; - Figure 3 is a diagram similar to that of Figure 2 for a negative direction of movement of the piston of the actuator.

The hydraulic actuator 13 of FIG. 2 is intended to equip an actuation mechanism for automated or semi-automated transmission, such as a gearbox of a motor vehicle (not shown).

2903460 4 It allows to operate a gearbox fork (not shown) of the vehicle for the passage of gears in this vehicle. When the actuator is used within an automatic transmission, its movement is controlled by a management system according to the current engine speed. When this actuator is disposed within a semi-automatic gearbox, its movement is guided by a speed selection lever (not shown) operable manually by the driver of the vehicle. In both cases, a control unit 20 delivers a control current i depending on the desired direction of movement 15 for the actuator 13 and the desired amplitude of this displacement. This actuator 13 comprises a double-acting jack 14 provided with a piston 15 movable along a horizontal main direction A1, A'1 in two opposite directions marked respectively by F1 in FIG. 2 and by F2 in FIG. 16 of the piston 15 separating the cylinder 14 into two pressure chambers 17, 18. Each of these chambers 17, 18 is selectively connected to a hydraulic unit such as a source of pressurized fluid 19 or to a fluid recovery vessel 21 located at a pressure lower than the pressure of the fluid within the source 19. In the example of the figures, the container 21 is at ambient pressure.

The selective connection between the two chambers 17, 18 and the source 19 or between these chambers 17, 18 and the container 21 is provided by two three-way solenoid valves 22, 23. These solenoid valves 22, 23 are further controlled by the unit. 7 to control the amount of fluid through which these valves 22, 23 are passed as a function of the control current i delivered by this unit and thus the displacement of the piston 15 of the cylinder 14. More specifically, each valve 22, 23 is disposed at the intersection of three channels 22a, 22b, 22c, 23a, 23b, 23c which are a first channel 22a, 23a providing a connection between the valve 22, 23 and the source 19, a second channel 22b, 23b connecting the valve 22, 23 to the relevant chamber 17, 18 and a third channel 22c, 23c allowing communication between the valve 22, 23 and the recovery container 21. It should be noted that the first channels 22a, 23a define a situational junction e downstream of the pressurized source 19. Each valve 22, 23 can occupy an active state in which it puts in communication the channels 22a, 23a and 22b, 23b, and connects the relevant chamber 17, 18 with the source 19 accordingly. , as shown in FIG. 2 for the valve 22, causing the pressurized fluid to fill this chamber 17, 18 and consequently preventing the flow of the fluid from the chamber 17, 18 to the recovery container 21, the track 22c connecting the valve 22 to the receptacle 21 serving as a bypass for the fluid coming from the source 19 in the event of overflow of fluid in the chamber 17.

On the contrary, each valve 22, 23 can occupy an inactive state, as illustrated for the valve 23 of FIG. 2, in which it isolates the concerned chamber 17, 18 from the source 19 and establishes a communication between the channels 22b, 23b and 22c, 23c and thus a connection between the corresponding chamber 17, 18 and the container 21, so that the pressurized fluid from this chamber 17, 18 can flow to the non-pressurized container 21. The two valves 22, 23 occupy at each moment different states, for moving the piston 35 in the two opposite directions F1 and F2.

More specifically, as shown in FIG. 2, when the first valve 22 is in its active state, allowing fluid to be supplied to the first chamber 17, the valve 23 occupies its inactive state and allows the flow of the fluid from the second chamber 18 to the container 21. Thus, the pressurized fluid from the source 19 exerts, on the side of the first chamber 17, a force on the body 16 of the piston 15 tending to move it in the direction 10 spotted by F1. Similarly, and as illustrated in FIG. 3, when the first valve 22 is in its idle state and the second valve 23 is in its active state, the body 16 of the piston 15 is moved in the direction indicated by F2. In order to ensure a gradual displacement of the piston 15 in the direction A1, A'1, while having a low manufacturing and maintenance cost, one of the valves 22 of the actuator 13 according to the invention is of the type 20 proportional, the other valve 23 being of binary type. More precisely, the proportional valve 22 can define between the two channels in communication in its respective states, that is to say between the channels 22a and 22b in its active state and between the channels 22b and 22c in its inactive state, a partial opening of the fluid passage whose amplitude is adjusted as a function of the control current i. This valve 22 can therefore occupy a multitude of positions in each of its states (active / inactive), so as to modulate the amount of fluid 30 therethrough. According to a possible embodiment of the invention, the valve 22 is of the proportional pressure solenoid valve type, that is to say that the fluid pressure downstream of this valve 22 is proportional to the control current i, and it is the force exerted on the piston which is regulated. According to another embodiment, the valve is of proportional flow type, in which case the flow rate of fluid downstream of the valve 22 is proportional to the control current i, so that it is the displacement of the piston 15 which is regulated. On the contrary, the binary valve 23 does not define between the channels in communication in its respective states, namely between the channels 23a and 23b in its active state and between the channels 23b and 23c in its inactive state, that an opening of fixed fluid passage amplitude and occupies a single position in each of its states, namely a full open position between the channels 23a and 23b and total closure of the channel 23c in its active state and a position of full opening between the channels 23b and 23c and total closure of the channel 23a in its inactive state. The operation of the actuator according to the invention is described in detail below with reference to FIGS. 2 and 3. In FIG. 2, the proportional valve 22 occupies an active state in which it defines a particular opening, directly dependent on the current delivered by the control unit, which is itself fixed by the aforementioned management system when the control box speeds is in automatic mode, or by the actuation of the shifter exerted by the user when the gearbox is semi-automatic.

As a result, the pressurized fluid from the source 19 exerts on the piston 15 a force proportional to the control current i, so that the piston 15 is displaced in the direction indicated by F1. At the same time, the binary valve is controlled to its inactive state, and occupies its unique inactive position 2903460, for which it isolates the second chamber 18 from the source 19 and connects it to the container 21, allowing the flow of the surplus fluid flow due to displacement of the piston 15 in the direction F1, from the second chamber 18 5 to the recovery container 21. In Figure 3, the binary valve 23 is controlled to its active state and occupies its unique position in which it connects the pressurized source 19 to the second chamber 18, so that the pressurized fluid 10 exerts a force tending to move the piston 15 in the direction indicated by F2. At the same time, the proportional valve 22 is controlled to its inactive state and defines between the channels 22b and 22c a particular opening whose amplitude depends on the control current i, so as to regulate according to this current, the quantity excess fluid flowing between the first chamber 17 and the container 21 due to the displacement of the piston 15 in the direction F2. However, the opening defined by the proportional valve 22 controls as a function of the control current i the amount of fluid that can flow from the first chamber 17 to the container and limits the displacement of the body 16 of the piston 15 to the first chamber 17 since the hydraulic fluid is incompressible. Consequently, this opening of the valve 22 controls the value of the force exerted on the piston on the side of the second chamber 18, again as a function of the control current i. Thus, the piston 15 is displaced in the direction indicated by F2 by the application of a force proportional to the control current, with as much precision as for a displacement in the direction of the arrow F1 or that for the known actuator of Figure 1 which comprises two proportional type solenoid valves.

Claims (4)

  1. Hydraulic actuator comprising a double-acting cylinder (13) provided with two pressure chambers (17, 18) and a piston (15) displaceable in translation in a main direction (Al, A'1) in two opposite directions , a hydraulic power unit (19) for the cylinder (13), an unpressurized recovery vessel (21), and two three-way valves (22, 23) each interposed between a chamber (17, 18), the hydraulic unit (19) and the container (21), and each able to occupy an active state, wherein the valve provides communication between two channels (22a, 22b, 23a, 23b) respectively connected to the chamber (17, 18) and the group hydraulic (19) and isolates a channel (22c, 23c) connected to the container (21), and an inactive state in which the valve (22, 23) provides communication between the two channels (22b, 23b, 22c, 23c) connected respectively to the chamber (17, 18) and the container (21) and isolates the track (22a, 23a) connected to the hydraulic unit (19), the two van nes (22, 23) occupying at each moment different states so as to allow a gradual displacement of the piston (15) of the actuator (13) in two opposite directions, characterized in that one of the valves (22, 23) is proportional and defines in its two states an aperture of modulable amplitude between the two channels in communication (22a, 22b, 22c, 23a, 23b, 23c), the other valve (23, 22) is binary and defines in its two states an opening of fixed amplitude between the two channels in communication.   2. An actuator according to claim 1, wherein the proportional valve (22, 23) is of pressure solenoid type, the amplitude of the opening being a function of the fluid pressure downstream of the valve (22, 23). 2903460 10   3. An actuator according to claim 1, wherein the proportional valve (22, 23) is solenoid valve type flow, the opening amplitude being a function of the fluid flow downstream of the valve (22, 23). 5   4. Gearbox of a motor vehicle characterized in that it comprises a hydraulic actuator (13) according to one of the preceding claims and a control unit (20) delivering a control current (i) of the proportional valve (22, 23) of the actuator (13), the amplitude of the opening defined by the valve (22, 23) being proportional to the control current.