FR3027366A1 - DEVICE FOR TRANSMITTING MOTION BETWEEN A MOTOR PROVIDING A ROTATION MOVEMENT AND A RECEIVER MOVING INTO TRANSLATION - Google Patents

Abstract

Device for transmitting motion between a rotary motor (M) and a receiver (R) moved in translation comprising, around an axis of rotation (X), a transmission sleeve (10) free in rotation and in translation and carrying externally a first threaded segment (SF1) and a second threaded segment (SF2) with different threads, and a nut (20) fixed in translation and in rotation meshing with the first threaded segment (SF1) and a ring gear (30). internal thread engaged on the second threaded segment having externally a peripheral rotating drive surface cooperating with a rotational drive member (40) carried by the shaft (41) of the motor (M).

Description

Field of the Invention The present invention relates to a device for transmitting motion between a motor providing rotational movement and a receiver moved in translation.

STATE OF THE ART There are already multiple such motion transmission devices which transform a rotational movement into a translational movement. OBJECT OF THE INVENTION The object of the present invention is to develop a device for transmitting motion, which is simple and efficient, of small dimensions and which can in particular be integrated into a braking system. DESCRIPTION AND ADVANTAGES OF THE INVENTION For this purpose, the subject of the invention is a device for transmitting motion between a motor providing a rotational movement and a receiver displaced in translation. This device is characterized in that it comprises, installed around an axis of rotation, a transmission sleeve free to rotate about the axis and free in translation along the axis, this sleeve being connected to the receiver. tor, the sleeve carrying externally a first threaded segment and a second threaded segment. A fixed translational and rotational nut meshes with the first threaded segment of the sleeve, an internally threaded ring engaged on the second threaded segment and having externally a peripheral rotating drive surface cooperating with a drive member. in rotation carried by the motor shaft. The motion converter according to the invention, which is particularly compact in diameter, allows a very wide variety of applications with a constant or variable transmission ratio in the direction of increasing the ratio or the reduction and also a very considerable decrease in the pitch of the threading, which is not possible with a single thread while allowing the reversibility of the movement. The motion converter is economical to achieve and its operation is very reliable.

The transmission of the load is distributed over two thread segments; it allows a more efficient transmission and a particularly small footprint facilitating the integration of this motion converter in multiple types of actuators or assistive devices. The thread or threads variable pitch allow the adaptation of the variable output force for a constant input torque which facilitates the adaptation of systems to engines optimized when their power.

According to another feature, the threaded segments are in line on the outer surface of the sleeve, the peak diameter of the thread of the segment engaged with the thread of the nut being less than the crest diameter of the thread of the crown so that the segment Threaded sleeve can pass into the crown without its threading engages in the thread of the crown. This embodiment has the advantage of compactness in diameter compared to the state of the art and allows a good adaptation to the space available in general very limited for the integration of an actuator in a motor vehicle.

According to another feature, the first threaded segment and the second threaded segment intersect along the axis on the sleeve. This embodiment is particularly compact in diameter and length for the threaded ring, allowing its very effective integration for example in an electric brake booster system.

According to another characteristic, the sleeve is hollow. The hollow sleeve facilitates the integration of this motion converter in a mechanism that also requires the passage of an axis, a rod, a fluid line, an electric cable or a transmission cable to inside the sleeve to be connected to the receiver. The invention also relates to a braking system comprising an electric brake booster and a master cylinder, characterized in that it comprises a motion converter. The housing is fixed to the deck separating the vehicle engine enclosure and the passenger compartment, the converter having a hollow sleeve through which the control rod connects the brake pedal to the master cylinder and a motor controlled by the unit. controlling the braking system to drive the threaded ring according to the braking demand corresponding to the displacement of the control rod actuated by the brake pedal and detected by a sensor connected to the control circuit of the braking system. In particular the converter is a converter having a sleeve with crossed threads. In summary, the motion converter allows a good adaptation to the force / stroke actuation curve for controlling the master cylinder. In addition, the hollow sleeve allows the passage of the control rod of the pedal which reduces overall size, facilitates the control of the brake booster and the direct actuation of the master cylinder in case of failure of the brake booster.

Drawings The present invention will be described in more detail below with the aid of different motion transmission devices between a motor and a receiver, according to the accompanying drawings in which: FIG. 1 is a diagram of a first embodiment of embodiment of the transmission device according to the invention, FIG. 2 is a diagram of a second embodiment of the transmission device according to the invention, FIG. 3 is an exploded perspective view of an embodiment of FIG. 4 is a partially cut-away perspective view of a motion transmission device according to the second embodiment corresponding to the block diagram of FIG. 2, a motion transmission device corresponding to the diagram of FIG. FIG. 4A is a detailed view of a part of the nut of FIG. 4, showing more particularly the structure of the crossed threads, FIG. FIG. 5A is a detailed view of a portion of a variant of the nut similar to that of FIG. 4, showing the structure of the crossed threads, FIG. 5B is a detail view of several pads taken from FIG. 5A and showing the two net bottoms of the embodiment of the nut of FIG. 5A. Figure 6 is a schematic sectional view of a device of a braking system equipped with a device for the movement of movement between the brake pedal and the master cylinder.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION According to FIG. 1, the subject of the invention is a motion transmission device 1 receiving the rotational movement Ro of an engine M to exert a translation movement T (in both directions ) on a receiver R.

The transmission device 1, of axis xx consists of a sleeve 10, a nut 20 and a threaded ring 30. The sleeve 10, of axis xx is freely rotatable around the axis xx and free in translation along the axis xx. It is connected to the receiver R by a connecting member 2 transmitting the translation movement (T) of the sleeve 10 without transmitting its rotation movement R1. The sleeve 10 is externally provided with a first threaded segment SF1 and a second threaded segment SF2 both coaxial with the axis xx.

The nut 20 is locked in rotation and in translation. Coaxial with the axis xx, it is engaged by its thread 21 with the thread 11 of the threaded segment SF1 of the sleeve 10. The threaded ring 30 coaxial with the axis xx is engaged by its thread 31 with the thread 12 of the threaded segment SF2.

The threaded ring 30 has an outer circumferential surface 32, to cooperate in rotation with the output member 40, rotatable, carried by the shaft 41 of the motor M. The transmission link of the rotational movement between the members 32 and 40 is for example a connection by meshing, the peripheral surface 32 being toothed and the output member 40 being a pinion. The threaded ring 30 is rotatable around the axis xx but locked in translation. According to the embodiment of FIG. 1, the threaded segments SF1, SF2 are one after the other along the axis xx.

The diameter of the threaded segment SF2 is sufficiently greater than the diameter of the threaded segment SF1 so that the peak diameter DI2 of the thread 31 is greater than the diameter of the thread 11 and can not engage with the thread 11. The peak diameter according to FIG. the present description is the diameter of the geometric cylinder of circular section which passes through the top and / or the crest of a thread. This relationship between the diameters of the segments SF1, SF2 allows the sleeve 10 to move more freely in the threaded ring 30 without the thread 11 may come into engagement with the thread 31. The choice of the largest internal diameter of the thread 31 cooperating with the thread 12 of the threaded segment SF2 with respect to the homologous elements of the nut 20 and the threaded segment SF1 depends on the movement of the sleeve 10 according to the threads 11 and 12 depending on the movement that is to be communicated to the receiver R (range of motion). The "floating" sleeve 10 is subjected to the compound rotation imposed on it by the thread pairs 21/11 and 31/12 and results in a translational movement T more or less increased or decreased with respect to the movement of translation that would have the sleeve 10 which would be locked in rotation, and in the absence of the fixed nut 20. The threads 11, 12 are, by way of example, constant and in this case the multiplication or reduction ratio the movement will be constant. But it is also interesting to have for one or both threads, a variable pitch so as to vary the pitch resulting from the sleeve 10. This variant of the sleeve 10 allows to have a variable stroke applied to the receiver R , for an optimized input effort; that is to say, the torque to be applied to the ring 30 will thus be constant. It should also be noted that the sleeve 10, although shown hollow in the usual sense of a sleeve, is not necessarily hollow but may be a solid piece.

FIG. 2 shows an alternative embodiment of the motion transmission device of FIG. 1. This variant of the device generally has the same elements which, for this reason, bear the same numerical references supplemented by the suffix a; these different analogous or identical elements will not all be described in detail. The motion transmission device differs from the embodiment of the device 1 of Figure 1 by the combination of the threaded segments SFia, SF2a and threads 21a, 31a cooperating with the threads 1a, 12a thereof. According to FIG. 2, the movement transmission device 1a consists of a sleeve 10a, a nut 20a and a threaded ring 30a. The sleeve 10a is free in rotation and in translation around and along the axis xx of the device la. The sleeve 10a is connected to the receiver R by a connecting member 2a transmitting the translational movement T but not the rotational movement Ri of the receiver sleeve. The sleeve 10a has two SFia thread segments SF2a which do not follow one another along the axis xx but overlap at the periphery of the sleeve 10a while crossing one another. The threads 11a, 12a are therefore in opposite directions and the transmission will be reducing. The threads 1 a, 12 a may be at constant pitch or variable pitch of one or both threads 11 a, 12 a according to the stroke / constant or variable force to be supplied to the receiver R by a constant input supplied by the motor M. sleeve 10a is engaged by its threaded segment SFia with the nut 20a fixed in rotation and in translation and with the threaded ring 30a, fixed in translation and free in rotation. The threaded ring 30a is rotated by the motor M and its rotary member 40, for example a pinion 40 meshing with the toothing 32a of the threaded ring 30a.

The threaded segment SF 1 has a thread 11a extending for example over the entire length of the sleeve 10a and having a determined pitch. The threaded segment SF2a has a thread 12a crossing the thread 1a of the segment SFia, for example over the entire length of the sleeve 10a and having a determined pitch. As the sleeve 10a can circulate almost the entire length of the nut 20a and in the ring 30a, this reduces the axial length (along xx) of the ring 30a relative to the ring 30 of the first embodiment. It should also be noted that the sleeve 10a, although shown hollow, which is advantageous for many applications, can also be a solid part. The production of both the sleeve 10a and the threads 11a, 12a and the threads 21a, 31a does not present any particular difficulties. The crossed threads 11a, 12a of the sleeve 10a are made, for example, by first cutting one of the threads and then the other, crossing and physically cutting the thread already made so that the two threads 1a, 12a to not constant, will be delimited by curvilinear parallelepipedic studs whose four facets will be formed two by two by the geometric surfaces of the two threads as will be detailed in the following description.

In the case of one or two threads with variable pitch, the pads will be assimilated to deformed parallelepipeds. FIG. 3 is an axial half-section of an embodiment of the converter of the movement 1 of FIG. 1 showing the sleeve 10 that is mobile in rotation and in translation, the nut 20 fixed in translation and in rotation and the crown Fixed in translation but driven in rotation; this figure highlights the threaded segments SF1, SF2 and the peak diameter of the thread 31 of diameter greater than the peak diameter of the thread 11 of the threaded segment SF1 so that the sleeve 10 can "advance" in the thread 31 to the left according to Figure 3.

The means for driving the toothing 32 of the crown 30 is not shown. The nut 20 fixed in rotation and in translation is shown with, for example, its fixing orifice 13.

FIG. 4 is an axial half-section of an embodiment of the motion converter 1a of FIG. 2. This embodiment differs from that of FIG. 3 as already explained with reference to FIG. 4 shows the crossed threads 11a, 12a made on the outer surface of the sleeve 10a and leaving the studs 100a in the form of parallelepipeds curved facets forming the two threads 11a, 12a discontinuous which appears the bottom of the threads. Each thread 1 or 12a is representative of several threads each time parallel. FIG. 4A is an extract of FIG. 4 and FIG. 4B shows a pad of FIG. 4A highlighting the particular shape of this pad 100a taken as a representative example of the pads. The bottom of the thread 1 is schematized by a helical or quasi-helical band (not constant or not variable) whose direction is underlined by the double arrow F 1 a; it is the same for the next turn of the thread 1 la on the other side (behind) the pad 100a. Thus, the thread 1a is defined by its bottom or trace and at the pad 100a by the two facets 111a, 111aa, opposite.

Similarly, the thread 12a is shown schematically by a trace 12a; the thread 12a, also discontinuous, is delimited at the pad 100a by the facets 112a, 112aa, opposite. As a further remark, if the threads 11a, 12a are of variable pitch, then the threads 21a, 31a will be segmented for example they will be limited to half a turn to absorb the different curvatures of the facets 111a, 111aa, 112a , 112aa or variable steps, while having a sufficient length to overlap several pads 100a at a time and have sufficient guide and support contact depending on the efforts to be transmitted.

FIG. 5A shows the crossed threads 11b, 12b of the outer surface of a sleeve 10b not shown in detail but similar to that of FIG. 4. In this example, the threads 11b, 12b are representative of several parallel threads.

For the description of this variant, the same numerical references as in FIGS. 4, 4A, 4B will be used to designate elements analogous to these with the suffix b replacing the suffix a. This cross-threaded variant 11b, 12b differs from the embodiment of FIGS. 4, 4A, 4B by the depth of the thread 11b with respect to that of the thread 12b as evidenced by the detail view of FIG. 5B. The threads 11b, 12b are also delimited here by pads 100b resulting from the size of the crossed threads 11b, 12b. In the case of the particular example of FIG. 5A, there are in each case four parallel threads corresponding to the threading 11b and as many parallel threads for the threading 12b as appears on the right face of the sleeve 10b in FIG. 5A. Opposite facets 111b, 111bb form the threading 11b whose bottom 211b is bordered by opposite side surfaces 311b and 311bb connecting the facets 111b, 111bb. The facets 111b and the side surfaces 311b are on the right-facing side, visible in FIGS. 5A, 5B while the facets 111bb and the side surfaces 311bb are on the opposite, hidden side of the rows of studs 100b. The opposite facets 112b, 112bb are lower than the facets 311b, 311bb and the bottom 212b of the thread 12b is discontinuous, interrupted by the thread 11b of diameter less than that of the thread 12b. The outer surface of the pads 100b is on the same cylindrical envelope. The threads 31, 21 of the nut 20 and the threaded ring 30 will have a different peak diameter than the peak diameter of the thread 21 meshing with the thread 11b having an inside diameter smaller than that of the thread 31 which follows the thread. 12b less deep thread of the nut (Figure 5B).

In this variant, the threading 21 will be guided by the continuous part of the thread 1 lb bordered by the rings 311b, 311bb while the thread 31 will have to overlap at least two studs 100b so as not to lock.

FIG. 6 schematically shows a servo brake equipped with a motion converter according to the invention, which in this example is the converter 1a of FIGS. 2 and 4. The braking system as shown is limited to the master cylinder, for example a master tandem cylinder 200 connected to the brake pedal 210 by the control rod 211 cooperating with a sensor 220 detecting the braking request to transmit it to the management unit 230 which controls the motor not shown (for example the motor M) brake booster. The control rod 211 acts on the piston, for example the primary piston of the master cylinder 200 indirectly via the brake booster and directly in case of failure of the brake booster. The connection between the control rod 211 and the master cylinder 200 is only schematized without the various means, known per se, are represented.

For the part shown, the brake booster consists of the motion converter installed behind the apron 240 separating the EM motor vehicle enclosure and the passenger compartment H. the converter has a housing 250 fixed by means not shown to the apron 240 and housing the converter components 1a: the nut 20a integral with the housing 250, the threaded ring 30a driven by the brake booster motor and the sleeve 10a provided with the two outer threads 11a, 12a, crossed. The brake pedal 210 is hinged about the axis 212 and the sleeve 10a protrudes into the passenger compartment H behind the pedal 210. But this state is only that of the rest position. When the pedal 210 is actuated, the operation of the brake booster results in the movement of the sleeve 10a to the right according to FIG. 5 so that there is no protruding part or component limiting the amplitude of the pivoting stroke of the pedal.

This movement is preferably transmitted to the piston of the master cylinder 200 by the link 2a, schematized, which transmits only the translation / thrust and not the rotation of the sleeve 10a. The return movement of the sleeve 10a is controlled by the ring 30a driven in the opposite direction by the motor of the brake booster. The return movement of the piston or pistons of the master cylinder is ensured by the return spring of the master cylinder. In addition to this example of a braking system, the motion converter according to the invention can be applied to multiple mechanisms and actuators, in particular in the automotive field.

NOMENCLATURE OF THE MAIN COMPONENTS NOT SYSTEMATICALLY COMPRISING THE LITERAL SUFFIXES 1 Movement transmission device 10 Sleeve 11 Threaded threaded ring thread SF1 12 Threaded threaded ring thread SF2 13 Fixing hole 20 Nut 21 Thread 30 Threaded crown 31 Thread 32 External peripheral surface / Surface toothed 40 Rotating member 41 Output shaft 100 Plot 111,112 Facet (s) of a stud 211b, 212b Bottom (s) of the thread 1 lb 311b, 311bb Side surface (s) bordering the thread llb F1 1, F12 Thread direction M Motor R Receiver Ro Rotation speed of the rotary member 40 R1 Rotation speed of the sleeve 10 SF1 First threaded segment SF2 Second threaded segment xx Axis of the motion transmission device35