Parcel sorting facility equipped with a parcel injection device

Abstract

The invention relates to a parcel sorting installation (1) for parcels (2) comprising a main conveyor (3) designed to convey parcels sequentially, an injection conveyor (6) designed to inject a parcel onto the main conveyor, a transfer conveyor (7) designed to transfer a parcel onto the injection conveyor, and a control unit (8) designed to control the transfer and injection conveyors to form parcel injection cycles. Each injection cycle occurs within a predetermined cycle time, allowing the injection of a current parcel into a target pitch on the main conveyor. The cycle begins with an acceleration phase of the parcel on the transfer conveyor from zero speed to a transfer speed, followed by a conveying phase of the parcel at the transfer speed onto the injection conveyor, followed by an acceleration phase of the parcel on the injection conveyor from the transfer speed to an injection speed. Figure to be published: Fig. 2

Description

Title of the invention: Title of the invention

[0001] Parcel sorting installation equipped with a parcel injection device technical field

[0002] The invention relates to the field of parcel or package sorting and more particularly to parcel sorting installations equipped with parcel injection devices. Prior art

[0003] Most parcel sorting facilities today use sorting conveyors capable of conveying parcels in series and at very high speeds. These sorting facilities also include parcel injection devices designed to inject each parcel into a target pitch of the sorting conveyor, as described in document CN106269537.

[0004] This type of injection device systematically operates from a standstill and imposes the same acceleration cycle on all packages.

[0005] Injection devices are generally semi-automatic in the sense that each injection cycle is triggered automatically when the package is correctly positioned on the transfer conveyor by an operator and an available target pitch on the main conveyor is within injection range.

[0006] However, it is common for packages to be injected late onto the sorting conveyor, either outside the target step or straddling two steps, resulting in a high risk of rejection during package sorting.

[0007] Indeed, rounded, inclined or unbalanced packages can be delayed in starting, just as operators can unintentionally slow them down at the start of the injection cycle.

[0008] Moreover, the smaller the packages, the more they are shifted towards the rear of the step during their injection.

[0009] To avoid excessive rejection, the preferred solution today is to widen the strides on the main conveyor, which increases its footprint, and / or to reduce the speed of the main conveyor, which decreases the sorting throughput of the packages. Summary of the invention

[0010] The objective of the invention is therefore to solve the aforementioned problems.

[0011] To this end, the invention relates to a parcel sorting installation comprising a main parcel conveyor designed to convey parcels in series, an injection conveyor designed to inject a parcel onto the main conveyor, a transfer conveyor designed to transfer a parcel onto the injection conveyor, and a control unit designed to control the transfer conveyor and the main conveyor. injection to form package injection cycles, each injection cycle taking place within a predetermined cycle time allowing the injection of a current package into a target step of the main conveyor and beginning with a first phase of acceleration of the current package on the transfer conveyor from zero speed to a transfer speed, followed by a phase of conveying the current package at the transfer speed on the injection conveyor, followed by a second phase of acceleration of the current package on the injection conveyor from the transfer speed to an injection speed, characterized in that the control unit is parameterized to start each injection cycle of a current package with a certain anticipation time,in that the control unit is configured to calculate a certain delay time taken by a current package on the transfer conveyor relative to a reference package, and to delay the second acceleration phase of the package on the injection conveyor by a certain adjustment time of at least said delay time.

[0012] The idea behind the invention is to allow time at each injection cycle to manage the possible delay of a current package.

[0013] The principle of the invention therefore consists of triggering the injection cycle in advance of a triggering time allowing the injection of a current package centered in a target pitch, and then triggering the acceleration of the injection conveyor in advance if the package has fallen behind the transfer conveyor so that the current package can catch up and be injected centered in its pitch.

[0014] The sorting installation according to the invention may also have the following features:

[0015] - when the delay time is greater than a threshold time no longer allowing to insert the current package into the target pitch, the control unit in turn commands the injection conveyor to stop;

[0016] - the delay time is calculated according to a first calculation method consisting of subtract the time it takes for the rear front of the reference package to move from the rear front of the current package from a point upstream of the transfer conveyor to a point upstream of the injection conveyor;

[0017] - the delay time is calculated according to a second calculation method consisting of subtract the time it takes the geometric center of the reference package to move from the time it takes the geometric center of the current package to move from a point upstream of the transfer conveyor to a point upstream of the injection conveyor;

[0018] - the delay time is calculated by summing the first calculation method and the second method of calculation;

[0019] - the adjustment time is equal to the anticipation time minus the delay time. Brief presentation of the drawings

[0020] The present invention will be better understood and other advantages will become apparent upon reading the detailed description of an embodiment taken by way of non-limiting example and illustrated by the accompanying drawings, in which:

[0021] - [Fig. 1] [Fig. 1] illustrates in a very schematic way a sorting installation according to the invention;

[0022] - [Fig.2] [Fig.2] illustrates in a very schematic way an injection device for injecting packages onto a main conveyor according to the invention;

[0023] - [Fig.3] [Fig.3] illustrates in a very schematic way a chronogram of a cycle injection according to the invention for a package with delay and a package without delay;

[0024] - [Fig.4] [Fig.4] illustrates in a very schematic way the position of the packages in [Fig.3] relative to the steps of a main conveyor according to the invention;

[0025] - [Fig.5] [Fig.5] illustrates in a very schematic way a displacement kinetic of several packages running in an injection cycle during which a delay time measurement of said packages is carried out;

[0026] - [Fig.6] [Fig.6] illustrates in a very schematic way a chronogram of a cycle injection according to the invention for a delayed package and for which a catch-up of the delay is carried out;

[0027] - [Fig.7] [Fig.7] illustrates in a very schematic way the position of the package in [Fig.6] relative to the steps of the main conveyor according to the invention;

[0028] - [Fig.8] [Fig.8] illustrates in a very schematic way a displacement kinetic of a current package in an injection cycle during which a TB4 time measurement is performed;

[0029] - [Fig.9] [Fig.9] illustrates in a very schematic way a displacement kinetic of a current inclined package in an injection cycle during which a TB4* time measurement is performed;

[0030] - [Fig. 10] [Fig. 10] illustrates in a very schematic way a chronogram of a cycle injection according to the invention of a small package for which a catch-up of the delay is carried out;

[0031] - [Fig. 11] [Fig. 11] illustrates in a very schematic way the position of the package of the [Fig. 10] in relation to the steps of the main conveyor according to the invention;

[0032] - [Fig. 12] [Fig. 12] illustrates in a very schematic way a chronogram of a cycle injection according to the invention of a small package of rounded size for which a catch-up of the delay is carried out;

[0033] - [Fig. 13] [Fig. 13] illustrates in a very schematic way the position of the package of the [Fig. 12] relative to the steps of the main conveyor according to the invention. Description of a method of implementation

[0034] The invention relates to a parcel sorting installation 1 for parcels 2, as shown in [Fig. 1], intended to equip a sorting center or logistics platform for sorting parcels 2 or heterogeneous packages, and in particular "Small International Packages" known as PPLs

[0035] The sorting installation 1 of parcels 2 according to the invention typically comprises a main conveyor 3, here a parcel feed conveyor designed to convey parcels 2 in series and feed a loop sorting conveyor CP equipped with sorting outlets.

[0036] Without restricting the scope of the invention and as a simple alternative, the main conveyor 3 can also be in the form of a sorting conveyor.

[0037] The main conveyor 3 can be a belt conveyor whose steps 5 are virtual or physically identified, for example by cleats or markings, or a conveyor of receptacles, for example trays or buckets, linked to each other.

[0038] The sorting installation 1 according to the invention also includes a parcel injection device designed to convey parcels one by one and inject them onto the main conveyor, as shown in [Fig.2].

[0039] The injection device according to the invention comprises an injection conveyor 6 designed to inject each package 2 onto the main conveyor 3 and a transfer conveyor 7 designed to transfer each package 2 onto the injection conveyor 6.

[0040] The sorting installation 1 further includes a control unit 8 designed to control the transfer conveyor 7 and the injection conveyor 6 to form injection cycles of parcels 2.

[0041] An injection cycle according to the invention corresponds to a movement of a package 2 running on the transfer conveyor 7 and the injection conveyor 6 during a predetermined cycle time and allowing the injection of said package 2 into a target step of the main conveyor 3. Each injection cycle begins with a first phase of acceleration of the package 2 running on the transfer conveyor 7 from a zero speed V0 to a transfer speed VI, followed by a phase of conveying the package 2 running at the transfer speed VI on the injection conveyor 6, followed by a second phase of acceleration of the package 2 running on the injection conveyor 6 from the transfer speed VI to an injection speed V2.

[0042] The control unit 8 is also parameterized to control the acceleration of the transfer conveyor 7 and the injection conveyor 6 so that it does not exceed a maximum tolerable value above which the risk of slippage of the packages 2 is significant.

[0043] Thus, by way of non-limiting example and in order to have a limited footprint, the transfer conveyor 7 may be rectangular and of length L1 equal to the maximum diagonal of the packages 2 that can be injected into a pitch 5, while the injection conveyor 6 may be trapezoidal with a median length L2 equal to the maximum diagonal of package 2 increased by the distance required to accelerate package 2 from the transfer speed VI to the injection speed V2.

[0044] The transfer conveyor 7 can also be equipped with a template 9 for positioning the current package 2 and means for automatically detecting the presence, size and position of said current package 2 on the transfer conveyor 7 and on the injection conveyor 6.

[0045] Thus, the template 9 allows, when the transfer conveyor 7 is stopped, to discriminate between packages 2 that are too large Xmax, for example here with a width greater than 350mm, and to wedge packages 2 of the appropriate size in portrait or landscape mode.

[0046] The width X of the package 2 wedged against the template 9 is then its dimension parallel to the main conveyor 3.

[0047] The detection means according to the invention are, for example, in the form of photoelectric cells, here by way of example cells B1 to B4:

[0048] B1 detects the presence of a current package 2 in a corner O of template 9;

[0049] B2 detects the passage of a package 2 currently exiting the transfer conveyor 7;

[0050] B3 detects the passage of a package 2 currently at the exit of the injection conveyor 6;

[0051] B4 allows discrimination between large parcels 2 and small parcels 2 (X > Xthreshold).

[0052] However, it sometimes happens that the current package 2 to be injected falls behind during the acceleration phase of the transfer conveyor 7 compared to a reference package 2'.

[0053] Figure 3 shows a timing diagram of an injection cycle, with a current package 2 shown as a solid line and a reference package 2' shown as a dashed line without any delay. The delayed package 2 arrives straddling two steps of the sorting conveyor 3, while package 2' is injected centered in step 4, as shown in Figure 4.

[0054] By reference package 2' we mean a package of maximum size that can be accepted by the template 9. The reference package also allows us to define a reference injection cycle time Tcref, represented on the [Fig.3], allowing the reference package to be injected in a centered manner in the step 5, as well as a movement time of the back front of the reference package and a movement time of the geometric center of the reference package.

[0055] The data relating to the reference package 2' are here digital data stored in the memory of the control unit 8.

[0056] The control unit 8 can thus be parameterized to calculate the delay time TG of a current package 2 according to a first calculation method consisting of subtracting the time Tref that the rear front of a reference package takes from the time TB2 that the rear front of said current package 2 takes to move from a point upstream of the transfer conveyor 7 to a point upstream of the injection conveyor 6.

[0057] This first calculation method makes it possible here to identify a delay of the current package 2 by relation to the reference package, for example due to a rounded shape, poor positioning, poor balance of the current package 2 or when an operator unintentionally holds the current package 2.

[0058] Fig. 5 allows us to image the kinetics of movement of the rear front of a current package 2 to reach the injection conveyor 6 according to its positioning against the template and / or its size.

[0059] The control unit 8 can also be parameterized to calculate the delay time TG of said current package 2 according to a second calculation method consisting of subtracting the time taken by the geometric center of the reference package from the time taken by the geometric center of the current package 2 to move from a point upstream of the transfer conveyor 7 to a point upstream of the injection conveyor 6.

[0060] The second calculation method thus makes it possible to identify a delay in the current package 2 based on its measured or estimated size. Indeed, the difference in time taken by the geometric centers of the packages to cross the transfer conveyor 7 allows us to deduce a difference in size. Now, the smaller the size of the current package 2 is compared to the reference package, the more the current package 2 will be shifted towards the rear of the step 5 during its injection.

[0061] The measurements of the movement time of the rear front or the geometric center of the current packages 2 can be carried out using the detection means according to the invention.

[0062] Also, in order to provide the means to correct any delays of the current parcels 2 taken from the transfer conveyor 7, the control unit 8 is parameterized to start with an anticipation of a certain anticipation time Ta each injection cycle of a current parcel 2.

[0063] The anticipation time Ta may be of fixed duration and repeated systematically in all injection cycles.

[0064] The control unit 8 will then be parameterized to delay the acceleration phase of the injection conveyor 6 by a certain adjustment time Tw compensating at least (Ta-TG).

[0065] Tw is greater than (Ta - TG) here since the conveyors are not stopped during the injection cycle and consequently the package continues to advance at VI:

[0066] Tw = (Ta - TG) / (1 - VI / V2)

[0067] Advantageously, when the delay time TG is greater than a threshold time TS which no longer allows the current package to be inserted into the target pitch, the control unit can be configured to command the injection conveyor 6 to stop in return.

[0068] Thus, whether using the first calculation method or the second calculation method, each package injection cycle is systematically anticipated by a time of anticipation Ta while the second acceleration phase of the injection conveyor 6 is more or less delayed by a duration Tw which is calculated as a function of the delay time TG.

[0069] The control unit 8 can advantageously be parameterized to calculate the delay time TG by summing the first calculation method and the second calculation method in order to improve the recovery of the delay of the current package 2.

[0070] In addition, if the current package 2 does not have a delay time at the exit of the transfer conveyor 7, the control unit can be configured to delay the acceleration phase of the injection conveyor by the anticipation time Ta.

[0071] Example of injecting a package that is delayed due to its rounded shape:

[0072] A delay TG is calculated for a current package 2 of rounded shape during its travel on the transfer conveyor 7 by calculating a difference between the time TB2 taken by the rear edge of the current package 2 to exit the transfer conveyor 7, (i.e., to go from the upstream point of the transfer conveyor 7 to the upstream point of the injection conveyor 6, thanks to detection by cells B1 and B2) since the activation of the injection cycle triggered when the center of the target step on the main conveyor is at a distance V*Tcref upstream of the median axis of the injection conveyor (V being the speed of the main conveyor), and the theoretical time Tref for the rear edge of a reference package 2' to cross the transfer conveyor 7 determined as follows:

[0073] Tref = VI / A + L1 / VI

[0074] (where A is the acceleration, VI the transfer velocity and L1 the length of the transfer conveyor)

[0075] On the other hand, it will be understood that if no delay of the current package 2 is detected, the delay TB2 will then correspond to the time taken by said current package 2 to travel the distance L from the activation of the acceleration phase of the transfer conveyor 7 (that is to say to go from the point upstream of the transfer conveyor 7 to the point upstream of the injection conveyor 6, thanks to the detection by the cells B1 and B2).

[0076] Furthermore, a current package 2 which comes out ahead of the transfer conveyor 7 (either because it was not properly secured against the template, or because it has rotated or due to an inaccurate detection) would not cause an immediate start of the acceleration of the injection conveyor 6, which must not occur before the end of the acceleration phase of the transfer conveyor 7.

[0077] TG = Max[0; TB2 - Tref]

[0078] Thus, to compensate for the delay TG, since the second acceleration phase of the injection conveyor 6 was anticipated by the anticipation time Ta, the arrival of package 2 at the end of the injection conveyor 6 must be delayed by the duration (Ta - TG). The maximum compensable delay is therefore Ta.

[0079] However, the injection conveyor 6 receives the package at the transfer speed and maintains it at this speed until the acceleration phase of the injection conveyor 6.

[0080] The control unit 8 can in this case be configured to delay the acceleration of the injection conveyor 6 by a duration Tw greater than (Ta - TG):

[0081] Tw = (Ta - TG) / (1 - VI / V2) = (Ta - TG) / CRw

[0082] For example, for V1 = 1 m / s and V2 = 2.16 m / s, the factor 1 / CRw is close to 1.9

[0083] CRw is a coefficient that is used in the calculation of Tw for a package rounded or braked only for a small package: CRw = 1 - V2 / V1

[0084] The maximum value of Tw is limited here by the length L2 of the injection conveyor 6 because it is necessary that the current package 2 (or at least its center) has almost acquired the injection speed when it reaches the main conveyor 3.

[0085] In practice, the value of the maximum compensable delay (therefore of Ta) is on the order of 150 ms, which represents a significant correction capacity in the step (230 mm for a speed of the main conveyor V=1.53 m / s.

[0086] The timing diagram in [Fig. 6] shows the speed Vt of the transfer conveyor 7 and the speed Vi of the injection conveyor 6 in a standard package insertion cycle ending at Fi and shows, as an example, the speed Vc of a current package 2 that has fallen behind schedule, shown here as a solid line. The delay experienced by the current package 2 on the transfer conveyor is compensated for here by the delayed triggering of the acceleration of the injection conveyor 6 at the end of Tw. The current package 2 is thus perfectly timed with the arrival of step 5, as shown in [Fig. 7].

[0087] Package 2 therefore arrives at the same place on the main conveyor 3 and does not leave step 5.

[0088] Example of injecting a package that is late due to its small size:

[0089] It was found that a current package 2 of width X less than the maximum width Xmax (in the example according to the invention Xmax=350mm) which perfectly followed the injection cycle without falling behind in the direction of the first calculation method, was offset on the rear of step 5 by a certain duration Tmes:

[0090] Tmes=(Xmax - X) / 2

[0091] The measurement or estimation of the width of the current package 2 in relation to the package of maximum width Xmax amounts here to considering the geometric center of said current package 2 in relation to the geometric center of said package Xmax, geometric center which must be centered in the target step 5.

[0092] The offset of the current package 2 in the step 5 therefore amounts to determining the time difference between the geometric centers of the current package and the reference package on the transfer conveyor 7, i.e. Tmes.

[0093] The control unit 8 according to the invention thus makes it possible to compensate for this delay time, by advancing the arrival of the package 2 at the end of the injection conveyor 6 of the duration :

[0094] 0.5 (Xmax - X) / V

[0095] Since the injection cycle has been brought forward by the anticipation time Ta, it is necessary to delay the acceleration phase of the injection conveyor 6 by a duration Tw:

[0096] Tw = [Ta - 0.5 (Xmax - X) / V] / (1 - VI / V2) = [Ta - 0.5 (Xmax - X) / V] / CRw

[0097] However, the width of the current package 2 placed on the transfer conveyor 7 is not not known in advance and being very variable from one package to another, it is necessary to measure or estimate this width no later than when the current package 2 comes out of the transfer conveyor 7.

[0098] The sorting installation 1 according to the invention may in this case be equipped with an optical sensor (camera or laser) placed above the transfer conveyor 7 to measure the dimensions of the current package 2 when stopped on the transfer conveyor 7, a curtain of presence detection cells along the template to estimate the width of the current package, or use existing cells such as cell B4, which is responsible for discriminating between large and small packages (> or < the threshold Xseuil, typically on the order of 250 mm).

[0099] Thus, when cell B4 is initially obscured by a current package 2 with a width > Xseuil, but less than Xmax, it is understood that the width X of the package cannot be estimated. This necessitates applying a small fixed lead (typically 30 mm).

[0100] When cell B4 is initially obscured by a current packet 2 of width < Xthreshold, the apparent width Xapp of the current packet 2 can be estimated as follows: - record a delay TB4 between the start of the acceleration phase of transfer conveyor 7 and the occultation of cell B4, - record the TB4* delay between the start of the acceleration phase of transfer conveyor 7 and the un-occulting of B4, - and

[0101] if TB4 > Tl (=V1 / A acceleration time of conveyor 1) then:

[0102] Xapp = (TB4* - TB4) VI cosa

[0103] or

[0104] if TB4 < Tl then:

[0105] Xapp = [VI (TB4 + TB4*) - 0.5 A TB42 - 0.5 Vl2 / A] cosa

[0106] Fig.8 represents the determination of the TB4 delay in the case of a non-inclined 2-current package, while Fig.9 represents the determination of the TB4* delay in the case of an inclined 2-current package.

[0107] In the case of an inclined package, it is indeed the apparent width Xapp of the current package 2 which is estimated and which is actually the quantity to be measured because it is this width which the current package 2 will ultimately occupy on the main conveyor 3.

[0108] [Fig. 10] represents the timing diagram of an injection cycle with centering of a current package 2 with a width of 100 mm. The injection of the current package 2 at time FI (end of insertion of the current package) onto the main conveyor 3 is advanced relative to the injection of the reference package 2' to recenter the current package 2 in its pitch 5, as shown in [Fig. 11].

[0109] Note that the measurement of the apparent width Xapp remains valid even if the current package 2 has not been perfectly placed against the template (rear corner of the package more or less distant from point O).

[0110] Example of injecting a delayed package without dynamic acquisition

[0111] If the dynamic acquisition of cell B4 or the real-time processing of this in training poses a problem, it is possible to consider a degraded strategy consisting of imposing a fixed systematic advance DA0 for large parcels (X > Xthreshold) and a larger advance DA1 for small parcels (X < Xthreshold).

[0112] The values ​​DA0 and DA1 are determined empirically or by simulation to obtain the best compromise taking into account the dimensional distribution of the packages to be processed.

[0113] Example of injection of a delayed package combining rounded shape and small size

[0114] The strategies described above are cumulative within the limit of the advance capacity Ta.

[0115] If the delay TG and the apparent width Xapp are observed at the outlet of the transfer conveyor 7, the overall delay to be imposed is:

[0116] Tw = [Ta - TG - 0.5 (Xmax - Xapp) / V] / CRw

[0117] Note that [TG + 0.5 (Xmax - Xapp) / V] is bounded between 0 and Ta. A delay of too great a parcel 2 of small width can therefore only be partially compensated.

[0118] By way of example, [Fig. 12] shows the injection of a current package 2, 100 mm wide, onto the main conveyor 3 with a delay of 100 ms. The acceleration phase is advanced, but the correction capacity limit is reached (Tw = 0), and the current package 2 is not perfectly centered in its pitch (see [Fig. 13]). More precisely, the package arrives in the pitch at FI (end of insertion of the current package), while the reference package arrives in the pitch at Fis (end of insertion of the reference package 2').

Claims

Claims

1. Sorting installation (1) for parcels (2) comprising a main conveyor (3) for parcels designed to convey the parcels in series, an injection conveyor (6) designed to inject a parcel onto the main conveyor, a transfer conveyor (7) designed to transfer a parcel onto the injection conveyor, and a control-command unit (8) designed to control the transfer conveyor and the injection conveyor to form parcel injection cycles, each injection cycle taking place in a predetermined cycle time allowing the injection of a current parcel in a target step (5) of the main conveyor and starting with a first phase of acceleration of the current parcel on the transfer conveyor from a zero speed to a transfer speed, followed by a phase of conveying the current parcel at the transfer speed onto the injection conveyor,followed by a second phase of acceleration of the current package on the injection conveyor from the transfer speed to an injection speed, characterized in that the control-command unit is configured to start in anticipation of a certain anticipation time Ta each injection cycle of a current package, in that the control-command unit is configured to calculate a certain delay time TG taken by a current package on the transfer conveyor with respect to a reference package and to delay the second phase of acceleration of the package on the injection conveyor by a certain adjustment time of at least said delay time.,

2. Parcel sorting installation according to claim 1, characterized in that when the delay time is greater than a threshold time TS no longer allowing the current parcel to be inserted into the target step, the control-command unit in return commands the stopping of the injection conveyor.

3. Parcel sorting installation according to claim 1 or 2, characterized in that the delay time TG is calculated according to a first calculation means consisting of subtracting the time Tref taken by the trailing edge of the reference parcel from the time TB2 taken by the trailing edge of the current parcel to move from a point upstream of the transfer conveyor to a point upstream of the injection conveyor.

4. Parcel sorting installation according to claim 1 or 2, characterized in that the delay time is calculated according to a second calculation means consisting of subtracting the time taken by the geometric center of the parcel

5.

6. of reference to the time taken by the geometric center of the current package to move from a point upstream of the transfer conveyor to a point upstream of the injection conveyor. Parcel sorting installation according to claim 3 and 4, characterized in that the delay time is calculated by adding the first calculation means and the second calculation means. Parcel sorting installation according to any one of the preceding claims, characterized in that the adjustment time is equal to the anticipation time minus the delay time.

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