CN107051832B

CN107051832B - Supply pump for liquid blanket application system

Info

Publication number: CN107051832B
Application number: CN201611048720.0A
Authority: CN
Inventors: 菲利普·德·塔霍特; 罗曼·盖伊特
Original assignee: Exel Industries SA
Current assignee: Exel Industries SA
Priority date: 2015-11-25
Filing date: 2016-11-23
Publication date: 2021-03-12
Anticipated expiration: 2036-11-23
Also published as: KR20170061090A; EP3173621A1; CN107051832A; FR3044052A1; FR3044052B1; EP3173621B1; JP2017110638A; US20170146008A1

Abstract

The present invention relates to a supply pump for a liquid blanket application system. The supply pump (1) comprises a motor (3) for driving at least two pistons and a drum (9) rotated by the motor, the drum comprising an outer cylindrical surface (90) having a cam-shaped groove (92), the pistons being respectively fixed to a rod (51, 61) on which a roller (53, 63) is also fixed, the roller rolling along the cam-shaped groove (92) so as to cause the piston connected to the roller to perform a translational movement along a corresponding translational axis (X5, X6) under the effect of the rotation of the drum (9). The position of contact of the cam groove (92) with one of the rollers is offset with respect to the position of contact of the cam groove with the other roller so that when one piston reaches a point of reversal in its direction of movement, the other piston is in motion. The pump further comprises a compensating device (10) for accelerating one piston when the other piston reaches a point of reversal in its direction of movement.

Description

Supply pump for liquid blanket application system

Technical Field

The present invention relates to a supply pump for a liquid blanket application system.

Background

The supply pump of a liquid covering application system for paint or the like usually consists of an electric or pneumatic motor, a hydraulic pump and a connecting device connecting said motor to the hydraulic pump. The electric pump refers to a supply pump having an electric motor, and the pneumatic pump refers to a supply pump having a pneumatic motor. The electric pump is preferred because of its better performance and lower cost of use, but there are problems in converting the rotary motion of the electric motor of the electric pump into an alternating linear motion of the hydraulic pump. When the direction of movement of the hydraulic pump is reversed, the speed of movement of its piston reaches zero, causing a pressure drop at the outlet of the pump. The electric pump used must therefore compensate for such reversals.

Some pumps are known that employ a single piston driven by a connecting rod-crank system. In such pumps, the rotational speed of the electric motor is controlled to obtain a constant flow rate. A pump employing a rack driven single piston is described in US2015/219819 a. Wherein said reversal is achieved by different teeth of the rack to reduce wear thereof. Neither of these systems avoids a pressure drop at the pump outlet.

There is also known a pump using two pistons arranged diametrically opposite each other, i.e. a Pi (Pi) radian-shift pump, said pistons being displaced by the rotation of a heart-shaped cam shaped and correspondingly configured so that, when one of said pistons reverses its movement, the other piston is not completely at the end of its stroke. However, since this system causes a continuous variation in the torque to be provided by the motor, a completely satisfactory effect is still not obtained. Furthermore, with the known heart cam design, the mechanism of the heart cam is arranged to have only one means for pushing the hydraulic pump piston. Therefore, in order to achieve movement of the piston in the opposite direction, a return mechanism is also provided.

Disclosure of Invention

The object of the present invention is to solve the above drawbacks by proposing a new supply pump for a liquid blanket application system, which supply pump can compensate more effectively for the reversal of its piston.

To achieve this object, the invention relates to a supply pump of a liquid covering application system, said supply pump comprising a motor driving at least two pistons. The supply pump further comprises a drum driven by the motor to perform a rotational motion, the drum comprising an outer cylindrical surface having a cam-type groove; the piston is fixed on a rod body, a roller is also fixed on the rod body, and the roller rolls along the cam type groove, so that the roller connected with the piston through the rod body performs translational motion along a corresponding translational axis under the action of the rotary motion of the roller; the contact position of the cam-shaped groove with one of the rollers has an offset angle with respect to the contact position of the cam-shaped groove with the other of the rollers, so that when one of the pistons reaches a reverse point in its direction of motion, the other of the pistons is in translational motion; the supply pump further comprises compensation means for accelerating the speed of the translational movement of one of the pistons when the other reaches a point of reversal in its direction of movement.

According to the invention, an effective compensation of the pressure drop is achieved by accelerating the speed of the translational movement of the other piston during the reversal of the movement of one piston. The pressure achieved at the pump outlet is generally constant.

According to an advantageous alternative aspect of the invention, the pump described above may comprise one of the following features, or any technically realizable combination of several features:

-said compensation means comprise acceleration means for accelerating the rotation speed of the rotary motion of said drum for a preset duration before or after one of said pistons passes its reversal point: in this embodiment, the motor speed is increased and the torque is decreased when the motion is reversed, so that the required motor power remains constant;

-the acceleration means is a control unit for slave control of the rotational speed of the motor;

-said compensation means further comprise a pressure sensor arranged downstream of said piston, said acceleration means being adapted to increase the rotation speed of the rotary motion of said drum as a function of the pressure value measured by the pressure sensor;

-said compensation means are formed by two angular zones of said cam-type groove, having an inclination angle with respect to a plane perpendicular to the rotation axis of the drum that is greater than the inclination angle of the remaining angular zones of said cam-type groove: in this embodiment, constant speed and motor torque can be maintained while compensation is achieved;

-the value of the inclination angle of the angular sector forming the compensation means is twice the value of the inclination angle of the remaining angular sector of the cam-shaped slot;

-the supply pump comprises two pistons angularly offset by 90 ° from each other;

-the cam-type groove comprises two helical grooves, each of which extends for half the circumference of the drum, the two helical grooves being symmetrical with respect to a plane passing through the rotation axis;

-the offset angle between the rollers is 70 ° to 100 °;

-the offset angle between the rollers is 90 °.

Drawings

The present invention will be more readily understood and other advantages will become apparent from the following description of a supply pump according to the principles of the present invention. The supply pump is provided as a non-limiting example only and is described with reference to the accompanying drawings. In the drawings:

FIG. 1 is a perspective view of a pump according to a first embodiment of the present invention;

FIG. 2 is an enlarged view of detail II of FIG. 1;

FIG. 3 is a top view of the pump of FIGS. 1 and 2;

FIG. 4 is a cross-sectional view taken along plane IV-IV of FIG. 3;

FIG. 5 is a graph of rotational speed versus angular position of the motor of the pump of FIGS. 1-4;

FIG. 6 is a view similar to FIG. 4 and is an enlarged view of a pump according to a second embodiment of the present invention, wherein only the rollers and drums of the pump are shown; and

fig. 7 is a view similar to fig. 1 of a pump according to a third embodiment of the invention.

Detailed Description

Fig. 1 to 4 show a supply pump of a liquid blanket application system (not shown) according to a first embodiment of the present invention. The pump 1 comprises an electric motor 3 having a rotation axis X-X'.

Said motor is intended to drive two pistons 5 and 6, each mounted in a chamber 8 and slidable along respective translation axes X5 and X6 parallel to the rotation axis X-X'. The movement of the pistons 5 and 6 in the chamber 8 enables the delivery of pressurised liquid covering of paint or the like.

The motor 3 drives the pistons 5 and 6 through a transmission system comprising a drum 9 driven in rotation by the motor 3 about an axis of rotation X-X'. The transmission of the rotation of the motor 3 to the drum 9 may be direct transmission or may be indirect transmission via a gear reduction system (not shown).

The drum 9 comprises a cylindrical outer surface 90 centred on the rotation axis X-X'. The outer surface 90 has a cam groove 92. The pistons 5 and 6 are fixed to a first rod 51 and to a second rod 61, respectively, to which are also fixed a first roller 53 and a second roller 63, the

rollers

53 and 63 rolling along a cam-shaped groove 92, so that the pistons 5 and 6, connected to the

rollers

53 and 63 via the

rods

51 and 61, respectively, are made to perform a translational movement along translation axes X5 and X6 parallel to the rotation axis X-X', under the effect of the rotation of the drum 9.

In the illustrated embodiment, the cam-type groove 92 is formed by a continuous groove comprising two

helical grooves

94 and 95, each extending for half the circumference of the drum 9 and being symmetrical with respect to a plane P1 passing through the axis of rotation X-X' of the drum. The spiral groove 94 includes a cylindrical bottom surface 94a, an upper spiral wall 94b, and a lower spiral wall 94c, and the spiral groove 95 includes a cylindrical bottom surface 95a, an upper spiral wall 95b, and a lower spiral wall 95 c. The

rollers

53 and 63 selectively contact one of the upper

spiral walls

94b and 95b and the lower

spiral walls

94c and 95c along a contact line (not shown) perpendicular to the rotation axis X-X'.

In fig. 4, the motor 3, the drum 9 and the

rollers

53 and 63, respectively, appear twice because of the geometry of the cutting plane IV-IV.

When the drum 9 rotates on its own axis of rotation X-X', the contact between the

spiral walls

94b, 95b, 94c, 95c and the

rollers

53 and 63 generates a translational movement of the

rods

51 and 61, which movement is transmitted to the pistons 5 and 6, so that they can alternately suck the covering and then discharge it under pressure through the outlet of the pump 1.

Both pistons 5 and 6 have top and bottom dead centers corresponding to the opposite points in their translational movement direction. During each reversal the linear speed of the pistons 5 and 6 decreases and then passes through the zero point of speed, causing the pressure at the pump outlet to be cut off. Thus, when one of the pistons 5 and 6 slows down by reaching its reversal point, the slowing down of this speed must be compensated for by the other piston. Thus, according to the invention, the position of the contact point of the cam groove 92 with one of the

rollers

53 and 63 and the position of the contact point of the cam groove 92 with the other roller have a relative angular offset such that when one of the pistons 5 and 6 is at the point of reversal in its direction of movement, the other is in motion. Advantageously, as shown in fig. 4, the respective positions of the

rollers

53 and 63 are such that, when the roller 53 reaches its top reversal point, the roller 63 is approximately midway in its upward movement. This may partially compensate for the pressure drop caused by the reversal of the movement of the piston.

The offset angle a of the

rollers

53 and 63 is preferably between 70 ° and 100 °. Preferably, the offset angle a of the

rollers

53 and 63 is 90 °. The angle a is also the angle between the translation axes X5 and X6, respectively, and the plane formed by the rotation axis X-X'. The offset angle cannot be 180 ° because at this angle the pistons 5 and 6 will reach their reversal points simultaneously, so that mutual compensation cannot be achieved.

Thus, as shown in fig. 3,

rollers

53 and 63 are offset from each other by a quarter of a revolution of drum 9, which means that when roller 63 reaches the middle position of helical groove 95 (corresponding to the piston 6 being in half of its stroke), roller 53 reaches the intersection of

helical grooves

94 and 95.

In order to compensate more effectively for the reversal of the movement of the pistons, according to the invention, the pump 1 further comprises compensation means adapted to accelerate one of the pistons 5 and 6 when the other reaches its reversal point.

According to a first embodiment of the invention, said compensation means comprise means for accelerating the rotation speed of the drum 9 for a preset duration before or after one of the pistons 5 and 6 passes its reversal point, i.e. a control unit 10 schematically shown in fig. 1. Thus, during the whole period of time in which one of the pistons passes through the zero speed point after deceleration and then accelerates again, the control unit 10 accelerates the rotation speed of the drum 9, so that the translation speed of the other piston is also accelerated, thus achieving compensation for the aforementioned piston speed reduction. The method is illustrated by the curve in fig. 5, which shows the evolution of the rotation speed V of the drum 9 as a function of the angular position of the drum 9. This speed profile is sent by the control unit 10 to the motor 3 in the form of an electrical signal S10. Each time the drum 9 rotates one quarter of its turn, i.e. by an arc of pi/2, the pistons 5 or 6 reverse their movement and then compensate by raising the drum speed V in the vicinity of this angular position.

For example, the rotation speed of the drum 9 can be increased by 5 to 10 revolutions per minute.

The control unit 10 is preferably an electronic unit that performs driven control of the rotation speed of the motor 3.

For example, the angular interval before and after the point of reversal of the piston, i.e. the angular interval in which the speed of rotation of the drum 9 is accelerated, may be 0.14 to 0.28 radians.

Fig. 6 shows a second embodiment of the present invention. In this embodiment, the same elements as those of the first embodiment are denoted by the same reference numerals and operate in the same manner. Only the differences from the first embodiment will be summarized below.

In fig. 6, for the sake of clarity, only the drum 9 and the

rollers

53 and 63 are shown in the two positions shown in the cross-section of fig. 4.

In the embodiment shown in fig. 6, said compensation means may comprise, instead of or in addition to the means for accelerating the speed of rotation of the drum 9 described above, two angular sectors 97 on the cam-shaped groove 92, in which the inclination a97 with respect to the plane P2 perpendicular to the rotation axis X-X' is greater than the nominal inclination a92 of the remaining angular sectors of the cam-shaped groove 92. The remaining angular area is defined as the portion of the cam groove 92 that extends beyond the angular area 97. The middle portions of the

helical grooves

94 and 95 are each provided with an angular region 97 of greater slope. Thus, for

rollers

53 and 63 that are offset from each other by 90 °, when roller 53 reaches the reversal point (as shown on the left side of fig. 6), roller 63 contacts angular region 97 (as shown on the right side of fig. 6). In this way, the translation speed of the roller 63 along the axis X-X' is increased by the greater inclination of the

slot walls

94b, 95b, 94c and 95 c. Thus, the acceleration of the piston 6 fixed to the roller 63 can compensate for the deceleration of the piston 5 and the passing of the speed zero point. This may allow only a relatively small change in pressure at the outlet of the pump 1 when one of the pistons 5 and 6 reaches its reversal point.

According to an advantageous alternative aspect of the invention, the value of the inclination angle a97 is preferably twice the value of the inclination angle a 92.

Of course, the location of the angular region 97 at the mid-point between the

helical grooves

94 and 95 is related to the orientation of the

rollers

53 and 63 at 90 °.

Fig. 7 shows a third embodiment of the present invention. According to a third embodiment, the pump 1 can also comprise a pressure sensor 100 located downstream of the two hydraulic outlet conduits C1 and C2 of the pistons 5 and 6, so that the pressure at the outlet of the pump 1 and the pressure drop of one of the pistons after approaching the reversal point can be measured. The pressure sensor 100 is included in said compensation means and is connected to the control unit 10 or to any other means suitable for increasing the rotation speed of the drum 9 according to the pressure value measured by the pressure sensor 100 and sent to the control unit 10 in the form of an electrical signal SP. For this purpose, the increase in the speed of rotation of the drum 9 may be triggered when the pressure value at the outlet of the pump falls below a threshold value of, for example, 15 bar.

According to one embodiment of the invention (not shown), the pump 1 may comprise more than two pistons.

The features and alternatives of the above-described embodiments can be combined with each other to form new embodiments of the invention.

Claims

1. A supply pump (1) for a liquid blanket application system, the supply pump comprising a motor (3) driving at least two pistons (5, 6), characterized in that: the device also comprises a roller (9) which is driven by the motor (3) to rotate, wherein the roller (9) comprises an outer cylindrical surface (90) with a cam type groove (92); the pistons (5, 6) are fixed to a rod (51, 61) on which a roller (53, 63) is fixed, which rolls along the cam-shaped groove (92), so that the roller (53, 63), connected to the pistons (5, 6) via the rod (51, 61), performs a translational movement along a corresponding translational axis (X5, X6) under the effect of the rotational movement of the drum (9); the position of contact of the cam groove (92) with one of the rollers has an offset angle (a) with respect to the position of contact of the cam groove (92) with the other of the rollers, so that when one of the pistons (5, 6) reaches a point of reversal in its direction of movement, the other of the pistons (5, 6) is in translational motion; the supply pump (1) further comprising compensation means for accelerating the speed of the translational movement of one of the pistons (5, 6) when the other of the pistons (5, 6) reaches a point of reversal in its direction of movement,

the compensating device comprises an accelerating device (10), the accelerating device (10) is used for accelerating the rotation speed of the rotary motion of the roller (9) within a preset time length before or after one of the pistons (5, 6) passes through the reverse point of the piston.

2. The feed pump (1) as claimed in claim 1, characterized in that the acceleration device (10) is a control unit which slave-controls the rotational speed of the motor (3).

3. Supply pump (1) according to claim 1, characterized in that said compensation means further comprise a pressure sensor (100) arranged downstream of said pistons (5, 6), said acceleration means (10) being adapted to increase the rotation speed (V) of the rotary motion of said drum (9) as a function of the pressure value (SP) measured by this pressure sensor (100).

4. Supply pump (1) according to claim 1, characterized in that said compensation means are formed by two angular regions (97) of the cam-type groove (92), said angular regions (97) having an inclination angle (a97) with respect to a plane (P2) perpendicular to the rotation axis (X-X') of the drum (9), which inclination angle (a97) is greater than the inclination angle (a92) of the remaining angular regions of the cam-type groove (92).

5. Feed pump (1) according to claim 4, characterized in that the angular area (97) of the cam groove (92) forming the compensation means has an inclination angle (A97) of twice the value of the inclination angle (A92) of the remaining angular area of the cam groove (92).

6. Feed pump (1) according to claim 1, characterized by comprising two pistons (5, 6) angularly offset by 90 ° from each other.

7. Supply pump (1) according to claim 1, characterized in that said cam-type groove (92) comprises two helical grooves (94, 95), each of said two helical grooves (94, 95) extending for half the circumference of the drum (9), said two helical grooves (94, 95) being symmetrical with respect to a plane (P1) passing through the rotation axis (X-X') of the drum (9).

8. Supply pump (1) according to claim 1, characterized in that the offset angle (a) between the rollers (53, 63) is 70 ° to 100 °.

9. Supply pump (1) according to claim 8, characterized in that the offset angle (A) between the rollers (53, 63) is 90 °.