FR2543496A1 - DEVICE FOR AVOIDING SKATING OF A VEHICLE EQUIPPED WITH AUTOMATIC TRANSMISSION - Google Patents

Abstract

DEVICE TO AVOID SPIDING OF VEHICLES EQUIPPED WITH AN AUTOMATIC TRANSMISSION. IT INCLUDES A TORQUE T CONVERTER; AN AUXILIARY TRANSMISSION; ONE CONTACT ELEMENT BY FRICTION C1; A TRAIN OF GEARS; A MEANS OF MANUAL SELECTION; A VC ANTI-SLIP VALVE PROVIDED IN AN OIL PASSAGE. IT FURTHER INCLUDES A STARTING OIL PASSAGE 34 CONNECTED TO A SOURCE OF OIL UNDER PRESSURE P AND HAS A THROTTLE 33; AN ENGINE BRAKING OIL PASSAGE CONNECTS TO THE SAID PRESSURIZED OIL SOURCE P PARALLELLY AUDITS THE ENGINE BRAKING PASSAGE E A MEANS OF COMMUNICATION; THE WORK OIL PASSAGE 29 DESIGNED TO OPERATE IN RESPONSE TO A MANUAL SELECTION MEANS SELECTION OPERATION, SO AS TO MAKE THE START OIL PASSAGE 34 AND THE WORK OIL PASSAGE 29 AT THE MOMENT FROM STARTING, AND TO MAKE THE PASSAGE OF ENGINE BRAKING OIL WITH THE PASSAGE OF WORKING OIL, AT THE INSTANT OF BRAKING OF THE ENGINE E.

Description

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  Device for preventing skidding of a vehicle

  equipped with an automatic transmission.

  The present invention relates to a device

  designed to prevent skidding of vehicles equipped with an automatic transmission. When a shift lever is in the driving position (forward position) during a stop, vehicles equipped with an automatic transmission show so-called slippage phenomena, that is to say that the vehicle tends to

  move forward against the intentions of the con-

  Due to the pulling torque of a torque converter, such a slip force is able to apply to the motor a braking force when it is idling and empty. Therefore, to maintain a reference value of number of revolutions of the engine operating at idle, it is necessary to increase to a certain extent, at idle speed, the opening degree of a throttling valve in order to counterbalance the braking force. an increase in fuel consumption, which

  constitutes one of the main causes of fuel costs.

  vehicles equipped with an automatic transmission

matic.

  Taking into account the above, the Request-

  formerly proposed an improvement

  in that the idling condition of a vehicle is detected and the pressure on

  a starter coupling is derived to a

  see oil in order to interrupt the transmission of power between the engine and the drive wheels,

  which gives the load imposed on the engine, the same ni-

  in vehicles equipped with a transmission

  However, in the case of automatic transmission

  this development brings with it the problem of

254349 *

  the low gear gear used during idling, is also used to brake the engine although there is no difficulty when the whole system works reliably Indeed, if we admit that the system is maintained for

  for any reason in his condition avoiding a patient

  the effect exerted by the engine brake in the above-mentioned gear train is canceled in its entirety.

  this fact, in the vehicle in which the selective report

  is intended to make the engine brake

  in this gear train, said vehicle can only

  braking with the brake pedal, which

  directly locks the wheels This solution is clearly

  security is inadequate and it is necessary to propose an adequate countermeasure to ensure safety by eliminating incidents of this type. Examples of such incidents are a failure of the detection system which determines

  mistakenly that the vehicle is idling at an

  considered that although this vehicle is running, as well as a failure of the actuating mechanism which,

  although the detection system and the system of

  They operate in a correct manner, misprocesses the transmission in its condition in which it prevents slippage. In particular, the oil pressure selection valve, which constitutes the final actuating element, tends to be affected by sudden movements due to external parameters acting on the oil, so that in some cases it can not be reduced to its ineffective position

  because of the insufficient force of the return spring.

  This problem does not arise in vehicles in which there is a position of engagement of a report which puts the engine brake in action with the train

gearing of low speed.

  However, in vehicles in which engine braking is provided by the medium speed gear train, the gear ratio of this

  average speed train can not be reduced indefinitely

  because a gear ratio that is too strong affects negatively the action of the engine brake.

  in such vehicles, the reduction of energy consumption

  fueling knows limits.

  Consequently, an object of the present invention

  tion consists in proposing a device that avoids the

  of vehicles equipped with an automatic transmission, a device in which skidding of the starter gear is prevented while allowing this train

  gearing to provide engine braking, said

  positive being perfected so as to ensure an engine brake test even in case of failure of the mechanism

  anti-skid occupying its operating position.

  For this purpose, according to the invention, the

  The device has an oil passage that is used

  rabies, which is connected to a source of oil pressure and is provided in its central region with a constriction; a

  passage of the engine brake oil, which connects

  de-at a source of oil pressure parallel to the

  engine brake pipe; as well as a means

  a communication and inserted between the starting oil passage and the engine brake pipe, on the one hand, and the passage traversed by the working oil, on the other hand, this means of communication being designed to operate in response to a gearshift maneuver of the manual gearshift mechanism, so as to make the start oil passage and the working oil passage coincide during start-up and to match the moment of engine braking, the passage of the braking oil

  of this engine with said passage of the working oil.

  According to a first characteristic of the invention

  even if the valve prevents slippage

  fails even though it occupies a

  In an efficient manner, the high-pressure working oil is supplied to the passage of this working oil from the engine-braking oil passage, overcoming the restriction to which it is In this way, it is possible to put the motor brake into action without any failure, even in the case where the valve preventing slipping is defective.

  According to a second characteristic of the invention

  the valve preventing slippage has a cham-

  oil in which an oil pressure acts to

  bringing said valve to its closed position, however

  as means act in concert with a mechanism

  manual change of ratio so as to establish a communication between the oil chamber and a source

  oil pressure, when said selector mechanism

  manual operation is activated at the moment of braking

  Therefore, since the oil pressure deli-

  by the aforementioned source is introduced into the anti-skid valve concanitamnet braking engine so

  to bring this valve to its closed position, the

  The force is forcibly moved to put the engine brake into action safely, even in the event that the electric system actuating this anti-skid valve

  does not work properly when it detects

  the idle speed of the vehicle, or even in the event of

  a malfunction of said anti-skid valve due to foreign bodies trapped by the oil. The invention will now be described in more detail by way of non-limiting examples. FIG. 1 is a schematic view of an automatic transmission of motor vehicles to which the invention is applied, this transmission comprising three forward gears. and a single reverse gear; Figure 2 is a diagram illustrating the hydraulic circuit of the transmission shown in Figure 1;

  Figure 3 is a diagrammatic representation

  showing the connection of the oil passages when a manual valve occupies a braking position of the engine; Figure 4 is a diagram showing a

  hydraulic control circuit of another form of

embodiment of the invention; and

  Figure 5 is a schematic representation of

  to highlight the existing link between

  oil passages when a manual valve is moved

  to a position in which the

first gear engaged.

  Preferred embodiments of the present invention are described below in detail

  Referring to the accompanying drawings.

  If we first look at Figure 1 showing a schematic view of a transmission

  automatic motor vehicle system comprising three

  ports and a single report in progress.

  the output power of an E-motor is transmitted

  from a crankshaft 1, via a torque converter T, an auxiliary transmission M and a differential device Df (branches in this order), to drive wheels W and W ' The torque converter T has a finned wheel 3 connected to an input shaft 5 of the auxiliary transmission M, as well as a stator wheel 4 connected via a unidirectional coupling. has a

  stator shaft 4a being rotatable relative to the

  entry 5 by which it is supported The couple

  transmitted from the crankshaft 1 to the impeller wheel 2

  page is reflected in the impeller wheel 3, thanks to the dynamics of the fluid and when there is an amplification of this torque during this period,

  the stator wheel 4 supports the reaction of a machine

known in itself.

  A gear 8 for driving a pump

  The pressurized oil pressure P represented in FIG. 2 is provided at the right end of the impeller wheel 2, while a stator arm 4b for controlling an

  Vr control valve illustrated in Figure 2 is

  rigidly on the right end of the standard tree.

toric 4 a.

  Between the input and output trees 5

  6, parallel to the auxiliary transmission M, are

  mounted in parallel with a gear train Gi of

  speed, an intermediate speed gear train G 2

  a high-speed train G 3 and a train Gr

  reverse Gear train Gi low speed

  comprises a drive gear 17 connected to the input shaft via a low speed coupling Ci acting as a friction contact element for starting and braking the motor, and

  a driven pinion 18 fixed rigidly on the output shaft

  6 and meshing in said pinion 17

  G 2 average speed gears includes a drive gear

  19 connected to the input shaft 5 by means of a

  C 2 average speed, and a driven pinion which is connected to the output shaft 6 through a selection coupling Cs and which is engaged with said pinion 19 The high speed train G 3 is composed a driving pinion 21 secured to the input shaft 5,

  6 through a high speed coupling C 3.

  The reverse gear train G 1 comprises a drive pinion 23 integral with the drive pinion 19 of the medium speed gear G 2, a driven pinion 24 connected to the output shaft 6 via the selection coupling C s,

  as well as a crazy gear 25 which meshes with the two pins.

  23 and 24 The selection coupling Cs is

  tercalé between the driven pinions 20 and 24, these pinions and 24 being selectively connectable to the output shaft 6 by moving a selection sleeve 26 of said coupling Cs to a forward position to the left, or until at a walking position

  back to the right, looking at the figure.

  If only the Cl coupling of the range

  low speed is engaged when the selector sleeve

  26 is retained in its forward movement position as shown, the drive gear 17 is connected

  to the input shaft 5 to form the gear train

  ges Gi low speed, through which the torque is transmitted from said input shaft 5 to the output shaft 6 Then, when the coupling C 2 of the average speed range is engaged while taking of the coupling Cl low speed is removed, the driving gear 19 is connected to the input shaft 5 to form the gear train G 2 of the speed range

  means through which the couple is trans-

  said input shaft 5 to the output shaft 6

  that the coupling C 3 of high speed is engaged while taking the respective couplings Cl and

  C 2 of low and medium speeds is suppressed, the

  The lead 22 is connected to the output shaft 6 to form the high speed gear train G 3, through which the torque is transmitted from the input shaft 5 to the output shaft 6. when the selector sleeve 26 is brought to the mean reverse position is engaged, the driving gearwheels 23 and driven 24 are respectively connected to the input shaft 5 and the output shaft 6 to form the train Cr walking

  back through which the couple is trans-

  from said input shaft 5 to said output shaft 6. The torque echoed to the output shaft

  6 is transmitted from an output pinion 27, keyed on the ex-

  end of said shaft 6, to a pinion 28 more

  large diameter provided in the device Df differential.

  In FIG. 2, a hydraulic pump draws oil from an oil tank R and delivers this oil under pressure into a passage 29 of the working oil. The pressure of this oil is regulated to a predetermined value by a regulation valve Vr,

  after which it is delivered to a manual valve Vm.

  This oil pressure is indicated by a pressure line Pl. The regulation valve Vr comprises a

  spring 30 pressure regulator and a cylinder 31 lo-

  This spring 31 can be displaced to the left or to the right in order to adjust the load of said spring 30, a pressure regulator. The stator arm 4b comes into contact with the spring. outer surface of the cylinder 31 housing the spring, so as to apply the reaction force acting on the stator wheel 4, that is to say the reaction force to the stator A stator spring 32 for supporting the reaction force to the stator is connected to the cylinder 31, housing the aforementioned spring Therefore, if the stator reaction force increases, the stator spring 32 is compressed, so that the spring 31 is moved to the left to increase the load of the regulating spring 30 pressure, resulting in an increase in the oil pressure P, in the passage

254349 '

29 of the working oil.

  Part of the pressurized oil

  gulped by the valve Vr is introduced into the

  by means of a passage 34 of ad-

  oil mission, having a constriction 33 so

  to develop a pressure within said converts

  T in order to prevent cavitation, this pressure

  is determined by the amplitude of the choke

  33, by the force of the spring 37 of a check valve

  back 36, installed on an outlet passage 35 of the oil

  the torque converter T, and by other para-

similar meters.

  After she has gone through the check valve

  return 36, the oil is returned to the tank R in

  replacing an oil cooler 56 Excess part

  The pressurized oil delivered by the pump P is introduced into a passage 38 of lubricating oil.

  from the control valve Vr, and is dis-

  sorted to different lubrication members A pressure regulating valve 39 is connected to the passage 38 of the lubricating oil so as to ensure the pressure

of oil required at least.

  When the manual valve Vm occupies its

  neutral position as shown, the oil under pres-

  The valve supplied to this valve Vm is not distributed to any of the couplings Cl, C 2, C 3, nor to many other elements operating hydraulically. As a result, the setting of the three couplings Cl, C 2, C 3 is eliminated and that therefore, the torque of the motor E is not

transmitted to the wheels W, W '.

  When the manual valve Vm is moved one step to the left from its illustrated position and brought into a driving position D, the passage 29 of the working oil from the hydraulic pump P is put in communication with passages

$ 254 494.

  43 and 118, while the communication is

  between an oil passage 111 for starting and a passage 41a of working oil which opens into a cylinder 40a with oil pressure of the clutch Cl of low speed and provided with a unidirectional throttle On the other hand, the communication is interrupted between an oil passage 112 and a passage 41 b of working oil, opening into a cylinder 40 b pressure

  coupling oil C 2 of medium speed, the com-

  communication is also interrupted between a passage

  oil 113a and a discharge port 114.

  cation remains established between an oil passage 115 and an outlet orifice 116 The passage 43 of working oil is placed in communication with a spring chamber 42

  of a servo-motor Sm with oil pressure to move

  the selector sleeve 26 and, consequently, a piston

  tone 44 of said servo motor Sm remains in a position

  shift to the left (as shown) for

  nir, through a range of walkman

  45, said selector sleeve 26 in a position of

  As before, as illustrated in FIG. 1, the reverse gear gear Gr is put into a

  inefficient position A passage 46 for the admission of oil

  communicating with an inlet of a device for generating a proportional oil pressure

  at the speed of the vehicle (ie a control valve

  Vg), branch of the passage 29 of the working oil and a first passage 47 of oil signals extends to

  from an outlet port of the valve Vg.

  A rotation is printed at the control valve Vg (of a type known per se) around its own axis of rotation 49 by a pinion 48 meshing in

  the pinion 28 of large diameter of the device Df to diffe-

  Therefore, its angular velocity is proportionally

  the speed of the vehicle and, therefore, the regulating valve Vg can relax the oil pressure in proportion to this vehicle speed (i.e. a regulation pressure Tg) in the first pass 47 of oil signals under the action of the forcecentrifuge acting on the steering wheel 51 of a body

valve 50 with drawers.

  An oil passage 53 is passed through the working oil passage 43 and is connected to a first throttle valve Vt L via a modulating valve 54.

  54 consists of a pressure reducer loaded with iron

  by an elastic force and solicited at the opening

  re by the modulation pressure acting in an orifice

  output 54a, and determines the upper limit value

  of the pressure admitted into the first valve of

  This first Vt Q throttle valve, of a well-known type, comprises a slide 55, a control spring 58 which pushes this slide 55 to the left, a return spring 57 acting on said slide to the right, a control piston 59 supporting the outer end of said control spring 58, a control cam 60 to which a rotation is printed together with an increase in the opening degree of the throttle valve of the motor E, in order to push said control piston 59 to the left, an adjusting bolt 51 for adjusting the load of said spring

  57, as well as other similar bodies

  that the control piston 59 is moved to the left, the displacement of this piston causes a push towards the

  left exerted on the slide 55 by the control spring

  In this movement to the left, the pressure of the oil delivered in a second passage 52 of oil signals, acts on a shoulder 55 formed to the left of the

  drawer 55 so as to exert on this drawer 55 a push

  antagonistic to the right, so that in the end

  of account, the first throttle valve MTB can de-

  delivering, at the second passage 52 of oil signals, the oil pressure proportional to the opening degree of the throttle valve of the engine E, that is to say a

  Pt strangulation pressure. It will be observed that a movement

  Counterclockwise movement of the control cam 60 continuously throttles the flow rate between an oil passage 117 and the oil reservoir R. The first and second passages 47 and 52

  oil signals are respectively connected to chambers

  62 a, 62 b and 63 a, 63 b pilot oil pressure, the ends of a valve Vl associated with the range of low to medium speeds and an associated valve V 2

  in the range of medium to large speeds

  quent, drawers 64 and 65 of these respective valves

  Vl and V 2 receive at their two extreme faces the pressure

  Pg regulation and the throttling pressure Pt and they operate as follows: the valve 64 valve Vl associated with the range of low speeds

  medium-sized enterprises remains initially in a position

  which one has been moved to the right (as shown)

  by the force of a spring 66 and, therefore, the

  communication is established between an oil passage 118 and the working oil passage 41a through the oil passage 11, so that the clutch Cl of the low velocity range is subjected to pressure and Then, when the vehicle speed increases to increase the control pressure pg and the force to move the slide 64 to the left, under the action of the control pressure Pg overcomes the force, to move this drawer 64

  to the right under the action of the strangling pressure

f 543496

  Pt and spring 66, a ball 68 moving in

  connection to said slide 64 in a mechanism 67 with movement

  The snap-on mechanism, installed at the right end of said slide 64, passes over a fixed positioning projection 69 and said slide 64 is rapidly switched to a left position. The oil passage 111 is then put in communication with a oil drain passage 119 and the communication is established between the oil passage

  118 and a passage of oil 70 On the other hand, the communi-

  cation is removed between said oil passage 70 and

  In this condition, if the valve

  ve V 2 associated with the range of medium to large speeds

  of, occupies its represented position, the passage 70 com-

  munic with an oil passage 113 provided with a foreign

  unidirectional 121, and with the passage 41 b of working oil, through the manual valve Vm Thus, the operating oil is delivered to the cylinder 40 b oil pressure, to impose a coupling pressure C 2 of average speed, and

  This coupling results in the establishment of

  of the gear train G 2 of medium speed.

  When the speed of the vehicle increases further, the same phenomena occur in the valve V 2 associated with the range of medium to large speeds, the slide 65 of this valve V 2 being displaced to the left, under the effect of the pressure of Tg regulation increased, to communicate the passage of oil 113 with a passage 122 of oil purge, and the passage of oil 70 with the

  passage 41 c of working oil opening into the cylinder

  40c at oil pressure of the coupling C 3, the

  the range of high speeds. On the other hand, communication

  cation is interrupted between the passage 41c of working oil and the passage 123 of oil purge In this way, the coupling of the coupling C 2 of the range of average speeds is removed and, instead, the coupling C 3 of the high speed range is subjected to pressure and is engaged to form the gear train

  G 3 of the range of high speeds.

  In order to avoid an impact at the instant of the change of speed, accumulators 72, 73 and 74 are hydraulically connected in series with couplings C1, C 2 and C 3. A distributor 124 of type 1/2 is provided in passage 119. oil purge and a dispenser 125

  type 2/3 is located in passage 122 of the oil drain.

  The control pressure Pc from a second throttle valve Vt 2 is directed to chambers

  77, 78 and 79 of the counter pressure, said accumula-

  72, 73 and 74 via an oil conduit 106.

  The second throttle valve Vt 2 is interposed between an oil passage 105 bifurcating from the oil passage 53

  and the passage of oil 106, and it consists of a

  107, of a control spring 108 which pushes said

  drawer to the left, a control piston 109 sup-

  carrying the outer end of said control spring

  108, as well as a control cam 110 which turns

* joint-to an increase in the opening degree of the throttle valve of the motor E, in order to move said control piston 109 to the left When the piston

  command 109 is shifted to the left, resulting in

  that the control spring 108 pushes the drawer 107

  To the left In this movement to the left, the pres-

  The flow of oil delivered into the oil passage 106 acts on a shoulder 107 formed on the left of said slide 107, so as to exert on the spool 107 a counter-thrust to the right. In this way, the second throttle valve Vt 2 may, through the passage

  106, to supply chambers 77-79 with

  accumulator 72-74, the pressure of

  of Pc proportionally to the opening degree of the throttle valve of the motor E. It will be observed that a movement of the control cam 110 in the counterclockwise direction throttles the communication flow rate between the purge passage 120

  of oil, and the oil tank R, in a continuous manner.

  naked. When the speed of the vehicle drops, the valve 65 of the valve V 2 associated with the range of

  medium to large tesses is first moved to the right to allow a shift of the reports of the

  range from high speeds to medium speed range

  When the speed of the vehicle decreases further,

  the valve 64 of the valve Vl associated with the range of vi-

  low-to-medium speed is shifted to the right to allow shifting in the range of

  low speeds A characteristic of

  importantly, that the working oil supplied to the clutch Cl low speeds passes through the unidirectional throttling 75 during such a change in the ratio of the low speed range,

  the shift lever then occupies its po-

  D. The central region of the passage 41 has working oil is connected to the accumulator 72 and an oil passage 84, leading directly to the reservoir

  R, is connected to said central region of said passage 41a.

  A valve Vc preventing a skating, of the pilot type, is

  incorporated at mid-distance from the oil passage 84.

  The valve Vc preventing a slippage

  carries a slide 85 housed in a cylindrical chamber 86 formed in the intermediate portion of the passage 84, in order to subdivide this passage 84 into an upstream portion 84a and a downstream portion 84b, oil chambers 87 and 88

  being respectively delimited in the upper zones

  The drawer 89 has a resting spring 89 on the drawer 85 which is pushed up and down and is housed in the upper oil chamber 87. The drawer has a pair of upper and lower regions 90 and 91 between which is hollowed out. an annular groove 92, and orifices 93 and 94 establishing communication between this groove 92 and the upper and lower oil chambers 88 and 88 respectively. The annular groove 92 is in continuous communication with the upstream portion 84a and the region upper 90 opens and closes, during its vertical movement, an orifice 95 developed in the downstream portion 84b and opening into the chamber 86 of the valve -Cet orifice 95 is preferably shaped with a circular section or the like so that its effective opening area is

  gradually increased as the

90 is moving upward.

  An outer wall 97 pierced with an orifice 96 is located at the upper end of the chamber 86 of the valve and a solenoid valve 99, provided with a pilot valve 98 with a needle, intended to open and close

  the orifice 96 is located above said wall 97.

  The needle valve 98 is designed to close the orifice 96, thanks to the elastic force of a spring 100, and to

  open this orifice 96 when a solenoid 101 is excited.

  When it is open, the orifice 96 communicates with a passage 102 of oil branch connected to the part

downstream 84 b from the oil passage 84.

  When the solenoid 101 is excited and

  that the orifice 96 is open, the upper chamber of oil

  the 87 is put into communication with the oil tank

  R, through the orifice 96 and the passage of

  102, so that the oil pressure prevailing in said upper chamber 87 is decreased. As a result, the slide 85 is moved upwards by the acting force.

  on its second surface 85 b exposed to the pressure and turn

  born to the lower chamber 88, which causes the

  of the passage of oil 84 Since, at this stage,

  de, the pressure that prevails in the passage 41 has oil

  working (ie in the coupling Ci of

  speed) is determined by the elastic force of the return spring 89 and the area of the second

  surface 85 b of the slide 85, exposed to pressure, a phenomenon

  slippage can be prevented by adjusting said pressure to a value less than that of the pressure

  causing engagement of said Cl coupling.

  It will be observed that when the drawer

  64 of the valve Vl associated with the range of speeds

  medium-to-large speed range) is shifted to the left to cause shifting of the mid-range or high-speed range, the pressure of the medium-to-high speed range oil prevailing in the passage 41a takes a value of zero, so that the drawer 85 does not

  does not move upwards and that the anti-patina Vc valve

  ge is not actuated The solenoid 101 of the valve 99 is grounded via a transistor, at the base of which the output signal from a

  ET gate 140 is applied via a

  The input terminals of the AND gate 141 are connected to a speed change detector 142 for transmitting a high level signal when the

  shift lever was moved to the driving position

  D; a motor speed detector 143, which detects the revolution speed of the motor E and produces a high level signal when the detected speed is less than a reference value; a brake detector 144 which emits a high level signal, when

  the foot presses the brake pedal; as well as a

  throttle sensor 145 which generates a high level signal when the accelerator pedal is in position

empty race.

  So when the vehicle is immobilized

  at an intersection and that the foot is placed on the peda-

  the brake, the output signals of all the detectors 142 to 145 have high levels to excite the solenoid 101, which causes the opening of the anti-skid valve Vc, and prevents the occurrence of a phenomenon

skating.

  In the process of preventing a person from

  mentioned above, the throttle 75 located halfway through the passage of the oil allowing the start plays an essential role. If it is admitted that the diameter of the throttle 75 is indicated by d, that the diameter of the downstream portion 84b of the passage 84 of the valve Vc is Di, that a pressure delivered by the hydraulic pump P is indicated by P), and that the reference d designates the oil pressure prevailing in the passage 41a of the working oil, we obtain the following equation sdVpr _ ip = di

4 4

  If, in the above equation, we replace

2

  place P1, ú and d respectively by 8.61 Pa (8.5 kg / cm); 1.013 Pa (1.0 kg / cm) and 1.7 mi, D = 2.8 mm is obtained.

  factors must be considered in practice, and that is why

  what Di is adjusted in a range of 5 mm to 6 mm in

  in any case, Di does not have such a large value.

  To obtain a good reaction ability at the time of starting, the anti-skid valve Vc is arranged as close as possible to the coupling Ci of the range of

low speeds.

  Looking at Figure 3, when the

  Vm is moved to a position other than the driving position D, for example to a motor brake position (ie a holding position I).

  of the first speed), the communication between the

  41 a of working oil and the passage 111 of starting oil is removed according to the movement of the slide 80, but the communication is established between this passage 41 a and the passage of oil 43 via

  of the passage 126 of the brake oil of the engine which is

  parallel to said passage 111, as well as between

  said passage 41a and the passage 29 of the working oil opening into the hydraulic pump P As a result, the hydraulic pump P and the hydraulic cylinder 40a of the coupling Cl of low speed are directly

  connected to each other without any intervention from the

  unidirectional tranglement 75 in the passage 111 of starter oil Thus, the Cl coupling of low

  speed is engaged to establish the gear train.

  Gi of the low speed range so as to

be in action the motor brake.

  Alternatively, when the valve Vm is de-

  placed at a position II of restraint of the range of

  its averages or a reverse position Re, only the coupling C 2 is subjected to a pressure and engaged to establish gear gear G 2 speed

  medium or the reverse gear gear Gr.

  In particular, when the manual valve Vm is moved

  in the reverse position Re, the piston 44 of the

  -vo Sm engine receives oil under pressure on his fa-ce

  far left and Chamber 42 is put in communi-

  cation with the oil tank R, so that said piston 44 is moved to the right to establish the gear gear Gr of reverse, as mentioned i above In addition, a position Pk of the manual valve

  Vm denotes a parking position.

  It is now appropriate to explain the

  operation of this embodiment.

  It will be assumed that the manual valve Vm is moved to the driving position D to cause a deceleration and a stopping of the vehicle. As a result, the drawers 65 and 66 of the respective valves V 2 and V 1 are moved to the right to communicate the passage. oil 118 with the passage 111, used during startup, so that an oil pressure of about 0.981 bar is delivered to the passage 41 a of working oil because of the effect exerted by the throttling 75, which

  engages the Cl coupling of the low-voltage range

  When the vehicle stops at an intersection, the valve Vc preventing slippage is open, so

  that the pressure of the oil in the cylinder

  40 has fallen below the engagement pressure, so that the CI coupling is disengaged

  and that a slip phenomenon is prevented.

  According to the invention, braking

  motor can be tripped even if the anti-tamper valve Vc

  skating is prevented from moving away from his

  open position as a result of a short-circuiting of the tran-

  140, or because of the insufficient force of

  recall fate 89, particularly when the resistance to movement of said Vc valve is increased by

  foreign bodies closed by the oil In order to

  turn on the engine brake, the manual valve Vm is de-

  placed at the braking position of this engine, that is,

  say at position I retaining the first gear.

  As a result, as explained above in support of the

  gure 3, the communication between oil passage 111

  start-up and passage 41a of working oil is inter-

  broken, while ironing 126 of the brake oil

  engine stroke leading into the hydraulic pump P

  is placed in communication with the said passage 41

  sequence, a high pressure of about 8.61 Pa 10

  This is why, even when the valve Vc is kept open, sufficient oil pressure is required to cause the pump to engage the pump.

  Cl coupling is introduced into the hydraulic cylinder

  As a result, the gear train Gi of the low speed range is set to put the brake

  motor in action, although said valve Vc is now

open nude.

  If we consider that the pressure

  mentioned Pú 8,61 105 Pa is sufficient for transmitting

  be the maximum torque of the motor E and that the engine brake

  is the internal friction torque required

  so that this engine idles, we understand

  that the coupling engagement pressure Cl of the low speed range should not be as

  high, although it depends on the multiplier ratio

the Gi train.

  FIGS. 4 and 5 show another embodiment of the invention, in which the same numerical references are used to designate parts or organs identical to those of the form of FIG.

  described above In this type of realization,

  In addition, the flow passage 4a of the working oil is provided with a unidirectional throttle 75 '. In addition, a valve Vc' preventing slippage is designed so that its upper oil chamber 87 is connected to a passag-e. oil 127 through a check valve 128, allowing the oil to flow only in the direction of said upper chamber 87 The oil passage 127 can be placed in communication with the passage 29 d 'oil

  of work or with pass-through 116 leading to

  R, and this through the manual valve Vm Indeed, when this manual valve Vin occupies its

  neutral position N, shown in FIG. 4, and

  that said valve is in its driving position

  When D is shifted one step to the left beyond the neutral position N, communication is established between the oil passage 127 and the oil passage 116 through an elaborated groove 82. in the outer circumferential surface of the spool 80 of said valve

  manual Vm However, when this valve Vm is moved

  to its position I of retention of the first

  (see Figure 5), the groove 81 allows a

  communication between oil passage 127 and the passage

  29 of the working oil discharging into the hydraulic pump

  P. Between orifice 93 and the oil chamber

  87, there is a check valve 129 intended to

  born to prevent a back flow of oil under pressure

  from the upper chamber 87 to the lower chamber 88.

  This non-return valve 129 is held in a position

  pre-determined by the end of the return spring 89.

  This type of realization works from the

as explained below.

  It will be assumed that the vehicle is

  for example, at an intersection and that the foot of

  In this case, since all the detectors 142 to 144 generate high level signals, the output signal of the AND gate 141 has a high level and, thus, the transistor 140 between in action to energize the solenoid 101 In a corresponding manner, the pilot needle valve 98 is raised and the upper oil chamber 87 is brought into communication with the reservoir R through the orifice 96 of the bypass passage 102, of

  oil passage 127, manual valve Vm and pas-

  As a result, the pressure in the upper chamber 87 drops to allow the spool 85 to move upward to open the oil passage 84. As a result, the pressure of the oil prevails in the duct 41 has falls below the coupling engagement pressure CI low speeds which prevents the occurrence of phenomena

skating.

  When moving the vehicle, the

  pilot needle 98 has been lowered so as to ob-

  1, the slide 85 is moved up and down by the force of the return spring 89, thereby closing the oil passage 84, thereby inhibiting the skid prevention function. We will admit that

  in this case, said pilot valve 98 is maintained inopport-

  tuner in its high position by the uninterrupted excitation

  broken solenoid 101 due to an internal short-circuit transistor 140 In this case, the passage of oil 84

  is kept open, so that the oil pressure de-

  delivered to the clutch Cl low speeds is reduced Therefore, the engine brake can not be put into action if the device according to the invention is not, incorporated This difficulty can be overcome however.

  by the present invention, as will be apparent from the

  In accordance with the invention, when

  the manual valve Vm is moved to its position I of

  holding the first gear as shown in Figure 5,

  in order to cause engine braking, a communication

  between the oil passage 127 and the pas-

  wise 29 of the working oil, so that the pressure of

  the oil delivered by the hydraulic pump P enters into ac-

  87 In this way, a

  this acting up and down is applied to the drawer

  by the hydraulic pressure exerted on the

  85 a of this drawer 85 exposed to the pressure, this

  that said drawer 85 is moved downwards to

  in press fit with Cl coupling to

  speeds in order to achieve a sufficient effect of

engine braking.

  We will also admit that the resistance

  opposite to the movement of the drawer 85 is increased by

  of foreign bodies contained by the oil, so that the force exerted by the return spring 98 is not

  in itself sufficient to move said drawer 85 to its po-

  In this case, therefore, said drawer is pushed by the strong pressure of the oil, if

  although the oil passage 84 can be closed.

  In this type of embodiment, the manual valve Vm can take a position II for retaining the second speed between the driving position D and the position I for retaining the first speed. Communication is also allowed between the passage

  of oil 127 and the passage 29 of the working oil, when

  that said manual valve Vm comes to its position II of retaining the second speed With this embodiment,

  In case of failure, it is possible to move the

  85 when closed, when the manual valve is

  Vm selects the gear train corresponding to the second gear before the engine brake-is put

  in action with the train corresponding to the first

  This gives a great advantage from the point of view

  safety When the manual valve Vm takes its po-

  2, the oil pressure prevailing in the passage 41a is theoretically equal to 0, so that the forceagissant up and down on the slide 85 is increased further.

  manual valve Vm is moved from its position D to its po-

  sition I, it necessarily passes through its position II of retention of the second speed, to spare a

lapse of time.

25434.96

  In the described embodiments

  above, the high pressure is delivered through the

  manual valve Vm valve Vc preventing

  However, this arrangement is not limited to

  tif, and it is possible to use an individual selection valve in effective connection with said manual valve Vm or other means such as an electrical device. Communication between the oil passage 127 and the oil tank R, when the manual valve Vm occupies its driving position D can be established

  by another selection valve or distributor.

  It goes without saying that many changes

  may be made to the device described and

  represented, without departing from the scope of the invention.

Claims (2)

  1 A device to prevent skating of   vehicles equipped with an automatic transmission,   a torque converter (T), caused by a fluid; an auxiliary transmission connected to said torque converter (T) and having a friction contact element   (Cl) to establish a gear train to start   rage and braking of the engine (E); one-way selection   manually to move said contact element by friction   (Cl) between the starting position and the engine braking position (E); as well as an anti-skid valve (Vc) which, arranged in an oil passage bifurcating from a working oil passage for supplying oil of   said friction contact element (C "and   singing in an oil tank (R), is intended to-   said passage when said vehicle is idling idle, characterized in that it comprises a starter oil passage (34) connected to   a source of pressurized oil (P) with a throttle   (33) in its central region; an engine brake oil passage connected to said engine oil source   pressure (P) parallel to said braking passage of the   tor (E); and a means establishing a communication and interposed on the one hand between said passage of starting oil and said braking passage of the engine, and secondly, the passage of working oil (29)>, this means communication device being designed to operate in response to   a selection operation of said manual selection means   nual, so as to coincide said passage of oil   starting point (34) and said working oil passage (29) to the   both of the starting, and to match, at the moment of the braking of the motor {E), said passage of brake oil   of the engine with said working oil passage.   2 Device to prevent skidding   vehicles equipped with an automatic transmission, com- : 543494   taking a torque converter (T) cameand by a flui-   of; an auxiliary transmission connected to said converts   bearing memberT) and having a friction contact element (C1) for establishing a gear train for starting and braking the motor (E); manual selection means for moving said contact element   friction (Cl) between the starting position and the posi-   braking motor (E); as well as an anti-   slip (Vc) which, arranged in a two-way oil passage,   furious of a passage of working oil in order to   ter working oil said friction contact element CC 9 and opening into an oil reservoir (R),   and intended to open said passage when said vehicle   cule operates idle idle, characterized by the fact that said valve (Vc) preventing   skating is provided with an oil chamber in which   the oil pressure acts to push said valve (Vc) towards its closure; and in that means are provided in combination with said manual selection means for communicating said oil chamber   with the oil pressure source (P) in response to an operation   selection of said manual selection means at the moment of engine braking (E) 3 Device according to claim 2,   characterized by the fact that the manual selection means-   can occupy it, between the respective positions of   braking and braking the engine (E), in third position in which it establishes a gear train other than that for braking the engine (E); and by the fact that the means making the oil chamber communicate with   the source of oil pressure CP) are designed to allow   also to put a communication between said chamber and said source in response to the displacement of said means   manual selection at its third position.