EP3152415A1 - Device for positioning a camshaft - Google Patents

Abstract

The invention relates to a device (1) for angular positioning of a camshaft relative to a cylinder head of an internal combustion engine, said device (1) comprising a shim (5) having a jumper (6) comprising a body (7) and two parallel legs (8) which project from the body (7) and are capable of coming into contact with at least one flattened section made on the camshaft such that the shim (5) straddles the camshaft, the shim (5) also comprising an arm (10) projecting from the body (7), opposite the legs (8), said arm having an outer surface (11) and an inner surface, opposite one another, the device (1) also comprising an angular sensor (13) capable of being mounted on the inner surface or the outer surface (11).

Description

 DEVICE FOR POSITIONING A

 CAMSHAFT

The invention relates to the assembly of internal combustion engines of motor vehicles and in particular the positioning of at least one component of the engine relative to another. More specifically, the invention relates to the mounting and angular positioning of a camshaft with respect to a cylinder head of an internal combustion engine.

During the manufacture of motor vehicles, the engines are usually assembled on a dedicated assembly line, and then mounted on the vehicles once assembled.

 The assembly of internal combustion engines is a work of great precision during which operators must be vigilant relative positioning of its various components, a bad positioning may cause malfunction or premature wear of the engine.

 For camshafts, poor angular positioning generates advances or delays in the lifting of the valves, these advances or delays then generating an increase in the discharge of polluting particles into the atmosphere. This increase in the release of particulate pollutants can be detrimental to a vehicle, which may fail during test runs, leading to a bad publicity of the vehicle, or be classified in a category of vehicles to which a pollution tax is applied on the purchase price of the vehicle.

In addition, a poor angular positioning of (s) the camshaft (s) causes a decrease in engine efficiency and an increase in fuel consumption, forcing the owner of the vehicle to call a garage, driving to an immobilization of the vehicle.

[0006] In order to prevent a bad angular positioning of a camshaft, the operators in charge of mounting the engines, or the mechanics involved in the vehicle, use many methods and tools to ensure proper positioning of the camshafts. relative to the breech.

For example, when setting up the camshaft, the operators are made to perform many measurements on the tree to cams to adjust its positioning if necessary. This method gives good results, however it is long and tedious for the technician (ie for the operator in the factory or garage). Indeed, the technician must mount on the cylinder head, several supports on which he will move his tool (s) measurement. In addition, the placement of media from one engine to another can vary (even very slightly) which can distort the measurements.

 Another method of positioning a camshaft with respect to a cylinder head is described in patent FR 2 681 376. This method uses a positioning device in the form of a jumper having a body and two parallel legs protruding from the body, these legs being terminated by a flat surface and bearing, on both sides, on two flats made on the camshaft. In an alternative, the device comprises a pin, located between the legs, adapted to engage in a drilling of the camshaft so as to ensure the correct positioning of the device on the camshaft. In use, a technician comes to engage the device on the camshaft and comes to cooperate the flat surface of each leg on an upper surface of the cylinder head, so that the angular positioning of the camshaft with respect to the breech is insured.

 However, this method is not without drawbacks.

Indeed, there is an impossibility of positioning in case of failure on one of the components. For example, if the upper surface of the breech has a slight roughness, the flat surfaces of the two legs will not come into contact on the upper surface of the breech at the same time. Thus the angular positioning can not be realized.

In addition, in the event of defective cams of the camshaft, the angular positioning of the camshaft is assured but false. The technician can then visually observe the positioning fault and remove the camshaft and replace it with a faultless camshaft. However, this replacement can not be used to make corrections to the manufacture of the camshafts and the defective camshaft is then scrapped causing a waste of material and a financial loss for the manufacturer.

The present invention is intended to address the disadvantages of the prior art. A first objective is to provide an angular positioning device of a camshaft, simple and fast use.

A second objective is to provide an angular positioning device of a camshaft, simple and inexpensive manufacturing.

 A third objective is to provide an angular positioning device of a camshaft, to raise the value of the gap in case of manufacturing imperfection of the camshaft or the cylinder head.

A fourth objective is to provide a method of simple and fast use of the angular positioning device of a camshaft.

 For this purpose, it is proposed in the first place an angular positioning device of a camshaft with respect to an internal combustion engine cylinder head, this device comprising a shim having a rider comprising a body and two parallel legs. protruding from the body and adapted to come into contact with at least one flat surface formed on the camshaft so that the shim spans the camshaft in which the wedge also comprises an arm projecting from the body, opposite of the legs, this arm having an opposite outer face and an inner face, the device also comprising an angular sensor adapted to be mounted on the inner face or the outer face.

 The angular sensor allows the operator to record the difference (if it occurs) between the nominal position of the camshaft and the actual position of the camshaft and thus to follow the evolution of this difference during subsequent montages. Thus, the operator can correct, if necessary, the positioning of the camshaft if it is in a positioning tolerance zone, and if the positioning of the camshaft is outside the tolerance zone, check , using measurements on other fixtures, if there is a failure in the production of camshafts.

 In addition, the control time of the positioning of the camshaft, with the aid of the positioning device, is faster than the means usually used.

 [0020] Various additional features may be provided, alone or in combination:

the legs comprise an inner plane and an opposite external plane, the inner plane of one of the legs being able to come into contact with the flat surface of the camshaft;

 the arm extends one of the legs so that the wedge is shaped

"h";

 the outer plane and the outer face are coplanar;

- the arm is located between the legs of the rider;

 the angular sensor is mounted on the arm so as to leave a clearance between the top of the rider body and a side face of the angular sensor;

 the legs comprise, at one end, bevels so as to facilitate the spanning of the camshaft by the rider;

 the wedge is made of a metallic material having magnetic properties to allow cooperation with a lower surface of the angular sensor, itself magnetic.

 It is proposed secondly a method of using an angular positioning device as described above, this method comprising the steps of:

 calibrating the angular sensor with a square having a perpendicular vertical face and a horizontal face;

 zeroing the angle sensor on an upper surface of the cylinder head;

 assembling the angular sensor on the inner face or the outer face of the arm of the wedge to form the angular positioning device;

 position the device so that the rider straddles the camshaft and that one of the internal planes of the legs comes into contact with a flat part of the camshaft;

 adjust the camshaft and read the measurement indicated on the angle sensor, and

 remove the device from the camshaft and separate the angular sensor from the shim.

In one embodiment, the method comprises a second step of adjusting a second adjacent camshaft and reading the measurement indicated on the angular sensor, the angular sensor then being placed on the outer face or the inner face. the arm of the wedge, opposite the face on which is positioned the angular sensor for the adjustment of the first camshaft.

Other features and advantages of the invention will appear more clearly and concretely on reading the description below. after embodiments, which is made with reference to the accompanying drawings in which:

 Figure 1 is a perspective view from below of an angular positioning device of a camshaft;

FIG. 2 is a front view showing a first calibration step of the angular positioning device;

 Figure 3 is a perspective view from above showing a second calibration step of the angular positioning device on a cylinder head of a motor;

FIG. 4 is a front view showing a first step of using the angular positioning device;

 Fig. 5 is a perspective view showing the use of the angular positioning device in two different configurations;

 Figure 6 is a front view schematically showing a defect of angular positioning of a camshaft.

 In Figure 1 is shown a device 1 for angular positioning of a camshaft 3 3 with respect to a cylinder head 4 of an internal combustion engine.

 The device 1 comprises a shim 5 having a jumper 6 comprising a body 7 and two parallel legs 8 protruding from the body 7 and adapted to come into contact with at least one flat 9 made on the shaft 2 cams 3 so that the wedge 5 spans the camshaft 3. The wedge 5 also comprises an arm 10 projecting from the body 7, opposite the legs 8, this arm 10 having an outer face 11 and a face 12 internal opposites. The device 1 comprises an angular sensor 13 capable of being mounted on the inner face 12 or the outer face 11 of the arm 10 of the shim 5.

As seen particularly in Figures 1, 4 and 6, the legs 8 comprise an inner plane 14 and an opposite outer plane 15, the inner plane 14 of one of the legs 8 being adapted to come into contact with the flat 9 of the camshaft 2 3.

According to the embodiment shown in the figures, the arm 10 extends one of the legs 8 so that the wedge 5 is shaped "h" and the outer plane of a leg 8 of the rider 6 is coplanar with the outer face 11 of the arm 10 extending the leg 8. However, in a variant not shown in the drawings, the arm 10 is located between the legs 8 of the rider 6. In order to facilitate the handling of the shim 5 as will be explained below, it will be noted that the shim 5 comprises edge feeds at each junction of one part with another, ie between each inner plane 14 of each leg 8 with the body 7 of the rider 6 and between the inner face 12 of the arm 10 and the body 7 of the rider 6.

 Similarly, to facilitate the crossing of the camshaft 3 by the rider 6, the legs 8 comprise, at their end 16, bevels 17.

 Advantageously, the wedge 5 is made of a metallic material having magnetic properties, and the sensor 13 has a lower surface 18 also magnetic. Thus, the angular sensor 13 is magnetized on the arm 10 of the wedge 5 to form the angular positioning device 1.

 However, it should be noted that the angular sensor 13 is mounted on the arm 10 with a game 19 relative to the body 7 of the rider 6. More specifically, the game 19 is measured between the top of the body 7 of the rider 6 and a lateral face of the angular sensor 13, and is strictly greater than the value of the edge fillet between the internal face 12 of the arm 10 and the top of the body 7.

As seen in the figures, the yoke 4 comprises two outer walls 21 between which is located a wall 22 and middle walls 23 vertical, perpendicular to the wall 22 and extending between the middle walls 21, vertical walls 23 are provided with housings 24 receiving the camshaft 2. 3 The yoke 4 further comprises an upper surface 25 formed by the outer walls 21, the wall 22 medium and the walls 23 vertical.

 The camshaft 3 comprises a thickening forming a ring 26 carrying the flat surface 9. The camshaft 3 is connected to a pulley 27 on which is engrainer a belt (not shown).

According to the embodiment shown in the figures, the camshaft 2 comprises two flats 9 on which each inner plane 14 of the rider 6 bears.

In order to position a camshaft 3 with respect to a yoke 4, by means of an angular positioning device 1 as just described, a technician (factory operator or garage mechanic) follows the process below. First, the technician calibrates the angular sensor 13 using a bracket 28 as shown in Figure 2. For this, it places the lower surface 18 of the angular sensor 13 successively on a vertical face 29 (position shown in dotted lines) and on a horizontal face of the bracket 28 (position shown in solid lines) so as to zero on each face.

 Then, the technician places the angular sensor 13 on the yoke 4, as can be seen in FIG. 3, by placing the lower surface 18 of the angular sensor 13 in contact with the upper surface of the yoke 4, then again resets the angular sensor 13 so as to determine a reference plane for the angular measurement performed by the angular sensor 13.

 The technician then proceeds to the assembly of the angular positioning device 1 by positioning the lower surface 18 of the angular sensor 13 on the internal face 12 of the arm 10 of the shim 5.

 When the device 1 is assembled, the technician positions it on the camshaft 3 3 so that the jumper 6 spans the camshaft 3 and 3 that one of the internal planes 14 legs 8 comes to the contacting a flat 9 of the camshaft 3, and according to the embodiment shown in the figures, that the two inner planes 14 each come into contact with a flat 9.

 The assembly and positioning on the camshaft 3 are shown in Figure 4, the sequences being schematized by arrows.

Subsequently, as seen in Figure 6, the technician adjusts the position of the camshaft 3 3 and reads the measurement 31 displayed on the angular sensor 13, when the camshaft 3 is 3 correctly positioned, the measurement 31 being made with respect to the reference plane, that is to say with respect to the upper surface of the yoke 4. The positioning action of the camshaft 3 is illustrated, on the 6, the angle A between the outer face 11 of the shim 5 and the phantom line representing an initial position of the outer face 11 of the shim 5 of the device 1 before positioning the camshaft 3.

When the measurement 31 is read, the operator removes the angular positioning device 1 from the camshaft 3 and dissociates the angular sensor 13 from the shim 5. As seen in Figure 5, the engine comprises two shafts

2 to 3 cams to be positioned by the technician. The technician then realizes the positioning of a first shaft, corresponding to the positioning device 1 in solid lines, and then performs the same operation on the adjacent camshaft 3, corresponding to the positioning device 1 in dashed lines.

 However, it will be noted that for the positioning of the second camshaft 3 3, the angular sensor 13 is placed on the outer face 11 of the arm 10 of the shim 5. This particular positioning allows the positioning device 1 to be not blocked by an element of the vehicle, in particular when the positioning is carried out by a mechanic without the engine being removed from the vehicle.

 The device 1 for angular positioning of a camshaft 2

3 which has just been described has many advantages.

First, the device 1 is simple and fast to use. Indeed, the technician only has to perform a calibration of the angular sensor 13 and then take a reference to the cylinder head 4, assemble the device 1 and position it on the camshaft 3, position the latter and read the measurement on the angular sensor 13 and finally remove the device 1 from the camshaft 3 and dissociate its elements from each other.

 Second, the device 1 is simple and inexpensive in manufacturing. Indeed, the 13 angular sensor is advantageously from the trade, only the wedge 5 of simple shapes must be machined, for example using a numerically controlled machine, which ensures speed and quality of machining.

 Third, the technician can raise the value of the positioning distance of a camshaft 3 2 in case of misplacement of the camshaft 3 3 on the cylinder head 4 so as to allow, if necessary , a corrective action on the engines of the same series.

Finally, the method of using the positioning device 1 is also simple and fast, which reduces the cost of labor for a garage, or increase the rate of production in factories. production of vehicles.

Claims

1. Device (1) for angular positioning of a camshaft (2) with respect to a cylinder head (4) of an internal combustion engine, this device (1) comprising a shim (5) having a rider (6) comprising a body (7) and two legs (8) parallel projecting from the body (7) and adapted to come into contact with at least one flat (9 ) carried out on the camshaft (2) so that the shim (5) straddles the camshaft (2), characterized in that the wedge (5) also comprises an arm (10) protruding from the body (7), opposite the legs (8), this arm (10) having an opposite outer face (11) and an opposite inner face (12), the device (1) also comprising a sensor (13) ) angular adapted to be mounted on the face (12) internal or the face (11) external. 2. Device (1) according to claim 1 characterized in that the legs (8) comprise an inner plane (14) and an opposite plane (15), the plane (14) internal of one of the legs (8) being able to come into contact with the flat (9) of the camshaft (2) (3). 3. Device (1) according to any one of the preceding claims characterized in that the arm (10) extends one of the legs (8) so that the shim (5) is shaped "h". 4. Device (1) according to claim 2 characterized in that the outer plane (15) and the outer face (11) are coplanar. 5. Device (1) according to any one of claims 1 or 2 characterized in that the arm (10) is located between the legs (8) of the rider (6). 6. Device (1) according to any one of the preceding claims, characterized in that the angular sensor (13) is mounted on the arm (10) so as to leave a clearance (19) between the top of the body (7) of the jumper (6) and a side face (20) of the angular sensor (13). 7. Device (1) according to any one of the preceding claims characterized in that the legs (8) comprise, at one end (16), bevels (17) so as to facilitate the spanning of the shaft (2). ) with cams (3) by the rider (6). 8. Device (1) according to any one of the preceding claims characterized in that the shim (5) is made of a metallic material having magnetic properties to allow cooperation with a lower surface (18) of the sensor (13) angular , itself magnetic. 9. A method of using an angular positioning device (1) according to any one of the preceding claims characterized in that the method comprises the steps of: - calibrating the sensor (13) angular using a bracket (28) having a vertical face (29) and a perpendicular horizontal face (30);  zeroing the angular sensor (13) on an upper surface (25) of the yoke (4);  assembling the angular sensor (13) on the inner face (12) or the outer face (11) of the arm (10) of the wedge (5) to form the angular positioning device (1);  position the device (1) so that the jumper (6) straddles the camshaft (2) and that one of the inner planes (14) of the legs (8) comes into contact with a flat ( 9) of the camshaft (2) (3); - adjust the camshaft (2) and read the measurement indicated on the angular sensor (13), and  remove the device (1) from the camshaft (2) and dissociate the angular sensor (13) from the shim (5). 10. The method of claim 9 characterized in that the method comprises a second step of adjusting a second shaft (2) to cams (3) adjacent and reading the measurement indicated on the sensor (13) angular, the angular sensor (13) being then placed on the external face (11) or the internal face (12) of the arm (10) of the shim (5), opposite to the face (11, 12) on which the sensor ( 13) for adjusting the first camshaft (2) (3).