Drive device of slide door

A door drive device is disclosed, which comprises a guide rail for defining in the body of the vehicle a way along which the slide door moves; first and second pulleys arranged at spaced positions of the vehicle body; an electric drive unit for driving the first pulley; an endless belt put around the first and second pulleys with a slack thereof; a bracket for connecting a portion of the endless belt to the door; and a tensioning device for tensioning the endless belt. Due to provision of the slack of the belt, various advantages are obtained particularly when the door drive device of the invention is used in combination with other door controllers.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates in general to power slide doors of a motor 
vehicle, and more particularly to drive devices for driving the slide 
doors. 
2. Description of the Prior Art 
In order to clarify the task of the present invention, one conventional 
drive device of an automotive slide door will be described, which is 
disclosed in Japanese Patent First Provisional Publication No. 61-36480. 
The conventional door drive device comprises generally a drive cable which 
extends around a given oval path defined beneath a vehicle floor, several 
pulleys around which the drive cable is put, a drive drum which has both 
ends of the drive cable wound therearound, and a reversible motor which 
drives the drive drum. An electromagnetic clutch and a speed reduction 
gear are arranged between the drive drum and the motor. The drive cable is 
fixed to the door at a portion. 
Thus, when, with the clutch being engaged, the motor is energized to run in 
a given direction, the drive drum is rotated to drive the drive cable. 
With this, the door is moved forward or rearward. 
The reason of using the clutch between the drive drum and the speed 
reduction gear is to facilitate a movement of the door effected by manual 
labor. That is, when the door drive device gets out of order, the clutch 
is switched to assume its disengaged condition. Under this condition, the 
rotation of the drive drum carried out by manual movement of the door does 
not affect the speed reduction gear and the motor. If the manual movement 
of the door is carried out with the clutch kept engaged, a great 
resistance against the movement is produced by these devices. 
However, the above-mentioned conventional door slide device has the 
following drawbacks due to its inherent construction. 
First, by using the electromagnetic clutch, the door drive device becomes 
bulky, heavy, and costly. 
Second, combining the above-mentioned door drive device with other door 
control devices such as those disclosed in Japanese Patent First 
Provisional Publication No. 1-164647 is difficult. The devices disclosed 
in Japanese Publication 1-164647 are an automatic door closure which 
forces the door to shift to a fully closed latched position when the door 
comes to a half-latch position, and a door lock canceller which forces the 
latched condition of the closed door to be canceled prior to starting the 
opening movement of the door. In fact, it is difficult to obtain timed 
operations for all of these control devices. For example, if the door 
drive device starts to operate prior to cancelling the latched condition 
of the door, a great load is applied to the cable, the speed reduction 
gear and the motor. Furthermore, if, upon closing of the door, the speed 
at which the door is shifted by the door closure device, and the speed at 
which the door is moved by the door drive device, are not matched, an 
excessive load is applied to both the door closure device and the door 
drive device. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a drive 
device of an automotive slide door, which is free of the above-mentioned 
drawbacks. 
According to a first aspect of the present invention, there is provided a 
drive device for driving a slide door of a motor vehicle. The drive device 
comprises guide means for defining in a body of the vehicle a way along 
which the slide door moves; first and second pulleys arranged at spaced 
positions of the vehicle body; drive means for driving the first pulley; a 
flexible endless belt means put around the first and second pulleys with a 
slack thereof; connecting means for connecting a portion of the endless 
belt means to the door; and an auxiliary guide means mounted on the 
vehicle body between the first and second pulleys for guiding the movement 
of the flexible endless belt around the first and second pulleys. 
According to a second aspect of the present invention, there is provided a 
drive device for driving a slide door of a motor vehicle. The device 
comprises a guide rail secured to a body of the vehicle for guiding 
movement of the slide door; first and second pulleys arranged at spaced 
portions of the vehicle body beside the guide rail; an endless belt put 
around the first and second pulleys with a slack thereof; means for 
providing a meshed engagement between each of the first and second pulleys 
and the endless belt; an electric motor for driving the first pulley; a 
speed reduction gear operatively interposed between the electric motor and 
the first pulley; a bracket secured to the slide door, the bracket having 
an end by which a portion of the endless belt is grasped; and an auxiliary 
guide means mounted on the vehicle body between the first and second 
pulleys for guiding the movement of the flexible endless belt around the 
first and second pulleys. 
According to a third aspect of the present invention, there is provided, in 
a motor vehicle having a slide door, a system which comprises a door lock 
mounted in the slide door, the door lock having a latch plate which is 
engageable with a striker of a vehicle body to achieve a latched condition 
of the door; a door closure which shifts the door to its fully-closed 
latched position when the door comes to a half-latch position; a lock 
canceller which cancels the locked condition of the door lock when 
energized; and a drive device for driving the slide door, which comprises: 
guide means for defining in a body of the vehicle a way along which the 
slide door moves; first and second pulleys arranged at spaced positions of 
the vehicle body; drive means for driving the first pulley; a flexible 
endless belt means put around the first and second pulleys with a slack 
thereof; connecting means for connecting a portion of the endless belt 
means to the door; and an auxiliary guide means mounted on the vehicle 
body between the first and second pulleys for guiding the movement of the 
flexible endless belt around the first and second pulleys. 
According to a fourth aspect of the present invention, there is provided, 
in a motor vehicle having a slide door, a system which comprises a door 
lock mounted in the slide door, the door lock having a latch plate which 
is engageable with a striker of a vehicle body to achieve a latched 
condition of the door; a door closure which shifts the door to its 
fully-closed latched position when the door comes to a half-latch 
position; a lock canceller which cancels the locked condition of the door 
lock when energized; and a drive device for driving the slide door, which 
comprises a guide rail secured to a body of the vehicle for guiding 
movement of the slide door; first and second pulleys arranged at spaced 
portions of the vehicle body beside the guide rail; an endless belt put 
around the first and second pulleys with a slack thereof; means for 
providing a meshed engagement between each of the first and second pulleys 
and the endless belt; an electric motor for driving the first pulley; a 
speed reduction gear operatively interposed between the electric motor and 
the first pulley; a bracket secured to the slide door, the bracket having 
an end by which a portion of the endless belt is grasped; and an auxiliary 
guide means mounted on the vehicle body between the first and second 
pulleys for guiding the movement of the flexible endless belt around the 
first and second pulleys.

DETAILED DESCRIPTION OF THE INVENTION 
In the following, the door drive device of the present invention will be 
described in detail with reference to the drawings. 
In FIG. 1, there is shown a motor vehicle to which the present invention is 
practically applied. In this drawing, denoted by numeral 1 is a body of 
the vehicle which has a door opening (no numeral) at one side wall. The 
door opening has a horizontal flat bottom portion which serves as a step 
for passengers. Denoted by numeral 2 is a lower guide rail which is 
secured to the vehicle body 1 below the step of the door opening and 
extends substantially horizontally. 
As is best seen from FIG. 2, the lower guide rail 2 has a front portion 
gradually curved toward the inside of the vehicle body 1. 
Although not shown in the drawings, an upper rail is secured to an upper 
portion of the door opening, and a middle guide rail is secured to the 
side wall of the vehicle body 1 in the rear of the door opening. These two 
rails extend substantially horizontally. 
Denoted by numeral 3 is a slide door which is guided by the upper, middle 
and lower guide rails in such a manner that after being shifted laterally 
outward from its full-closed position, the door 3 is moved rearward in 
parallel with the side wall of the vehicle body 1. 
The door 3 has at its front lower portion a horizontal bracket 4 which 
extends toward the interior of the vehicle body. The bracket 4 is equipped 
at its leading end with both vertical and horizontal rollers 5 and 6 (see 
FIG. 2) which are rotatably engaged with and guided by the lower guide 
rail 2. The arrangement of these parts may be well understood from FIG. 4. 
As is seen from FIGS. 1 and 3, mounted to the lower surface of the step of 
the door opening is an elongate case 7 of a door drive mechanism "A". For 
this mounting, the case 7 has at is upper portion several mounting lugs 7a 
which are bolted to the step. The bottom wall of the case 7 is designated 
by numeral 7b. 
Within the case 7, there is installed a drive unit 8 which is located at a 
front portion of the case 7. 
As is seen from FIGS. 3 and 4, the drive unit 8 comprises a housing 9 and a 
lid 10 which covers an upper opening of the housing 9. Within the housing 
9, there is installed a reversible electric motor 11 whose output shaft 
11a extends vertically. A first smaller spur gear 12 is secured to the 
output shaft 11a to rotate therewith. Operatively engaged with the first 
gear 12 is a second larger spur gear 13a which is rotatably held by and 
between the housing 9 and the lid 10. A third smaller spur gear 13b is 
secured to a lower side of the second gear 13a to rotate therewith. 
Operatively engaged with the third gear 13b is a fourth larger spur gear 
15 which is coaxially secured to a vertically extending output shaft 14. 
In order to support the second, third and fourth gears 13a, 13b and 15, 
the housing 9 has a thicker supporting part 9a which is positioned above 
the bottom wall 7b of the case 7. Designated by numeral 19 is a bearing 
member which has a blind bore 19a into which a lower end of the output 
shaft 14 is rotatably received. The bearing member 19 has two walls 19b 
and 19c by which the thicker supporting part 9a is supported. 
The first gear 12, the second gear 13a, the third gear 13b and the fourth 
gear 15 constitute a speed reduction gear 16. 
The output shaft 14 has a lower portion to which a drive pulley 17 is 
coaxially secured by means a key 18. The cylindrical outer surface of the 
drive pulley 17 is formed with evenly spaced splines or teeth 17a for the 
purpose which will be clarified hereinafter. 
Referring back to FIG. 1, a driven pulley 20 is further installed at a rear 
portion of the case 7, which pulley has a vertically extending rotation 
shaft 21. Similar to the drive pulley 17, the cylindrical outer surface of 
the driven pulley 20 is formed with evenly spaced splines or teeth 20a. 
Around the drive and driven pulleys 17 and 20, there is slackly put an 
endless belt 22 which has a toothed inner surface operatively meshed with 
the teeth 17a and 20a of the pulleys 17 and 20. The teeth of the belt 22 
are denoted by numeral 22a. 
As is seen from FIGS. 2 and 4, one portion of the belt 22 is fixed to a 
belt holding bracket 23 which extends from the door 3. More specifically, 
the belt holding bracket 23 has a base portion 23b secured to the bracket 
4 through bolts 24 and nuts and extends horizontally under the bracket 4 
and projects into the case 7 through a longitudinally extending slot 25 
formed in an outside wall of the case 7. 
As is best seen from FIG. 4, the projecting end 23a of the belt holding 
bracket 23 is vertically raised for tightly grasping the belt 22. 
As is well seen from FIGS. 1 and 2, front and rear tensioners are installed 
in the case 7 to tension the belt 22, thereby taking up the slack of the 
belt 22. These front and rear tensioners are arranged to tension outside 
and inside parts of the belt 22, respectively. 
It is to be noted that the outside part of the belt 22 means one half part 
of the belt 22 which extends along an outside way between the drive and 
driven pulleys 17 and 20, while the inside part of the belt 22 means the 
other half of the belt 22 which extends along an inside way between the 
two pulleys 17 and 20. 
As is seen from FIG. 2, each tensioner comprises a vertically extending 
pivot shaft 27, an arm 26 having a base portion pivotally connected to the 
pivot shaft 27, a tension roller 28 rotatably mounted to a leading end of 
the arm 26 through a pin 29, and a spring 31 for biasing the arm 26 in a 
direction to press the tension roller 28 against the toothed inner surface 
of the belt 22. The spring 31 has one end hooked to a projection 26a of 
the arm 26 and the other end hooked to a projection 30 of the bottom wall 
7b of the case 7. 
Designated by numeral 32 is a stopper formed on the bottom wall 7b of the 
case 7, by which an excessive pivoting of each arm 26 toward the belt 22 
is restricted. An excessive pivoting of the arm 26 in the other direction, 
that is, in a direction away from the belt 22, is restricted by the 
projection 30. 
As is seen from FIG. 2, the front tensioner is so arranged that when the 
brackets 4 and 23 come to a junction zone 2c between straight and curved 
portions 2a and 2b of the guide rail 2, the belt 22 is separated from the 
tension roller 28, and when the brackets 4 and 23 are moved forward or 
rearward away from the junction zone 2c of the guide rail 2, the belt 22 
becomes into contact with the tension roller 28. With this arrangement, 
the raised inside end of the belt holding bracket 23 is prevented from 
contacting the tension roller 28. 
While, the rear tensioner is so arranged as to tension the belt 22 
constantly. 
As is seen from FIG. 2, a guide roller 33 is arranged between the drive 
pulley 17 and the rear tensioner, which constantly contacts the outer 
surface of the belt 22. 
Referring back to FIG. 1, within the door 3, there are installed a known 
door lock 35, a known lock canceller 36 and a known door closure 37, which 
are disclosed in the above-mentioned Japanese Patent First Provisional 
Publication No. 1-164647. Furthermore, an electric connector is employed, 
which comprises a body-mounted connector part 38 and a door-mounted 
connector part 39. When, under closing movement, the door 3 comes to a 
so-called "power feeding position" just before a half-latch position, the 
door-mounted connector part 39 is brought into engagement with the 
body-mounted connector part 38, so that thereafter electric feeding from a 
battery on the vehicle body to the electric devices in the door 3 becomes 
available. 
In the following, operation of the door drive device of the present 
invention will be described with reference to the drawings. 
For ease of understanding, the description will be commenced with respect 
to a condition wherein the door 3 is fully closed and latched. 
Under this condition, the brackets 4 and 23 and the endless belt 22 assume 
the positions as illustrated by solid lines in FIG. 2. The positions of 
the brackets 4 and 23 in this condition are denoted by reference "X1". As 
shown, each tension roller 28 is pressed against the belt 22 to softly 
tension the same with arm 26 abutting against the stopper 32. 
When a door open control switch (not shown) installed in a driver's room is 
manipulated to take the ON position, the electric power of the battery is 
fed to the lock canceller 36 through the connector (38 and 39). Thus, the 
locked condition of the door lock 35 is cancelled. 
Upon this, the door 3 is somewhat shifted outward due to the restoring 
force of a door seal and the biasing force applied to a latch plate of the 
door lock 35. In response to this outward shifting of the door 3, the 
portion of the belt 22 which is fixed to the bracket 23 is somewhat moved 
rearward. However, this rearward movement of the portion is quickly 
absorbed by the entire of the belt 22 by the work of the belt tensioners. 
When thereafter, the motor 11 is energized to run in a certain direction, 
the drive pulley 17 is rotated in a counterclockwise direction in FIG. 2. 
However, due to the meshed engagement between the drive pulley 17 and the 
belt 22, and due to the softly tensioned condition of the belt 22, the 
rotation of the drive pulley 17 does not induce an instant movement of the 
door 3 in the door opening direction. That is, at a first stage, the 
rotation of the drive pully 17 is used for only eliminating the slack of 
the belt 22. During this slack elimination, the two tensioners are 
gradually pivoted toward their inoperative positions as illustrated by 
phantom lines. 
When, due to elimination of the slack, the belt 22 becomes highly 
tensioned, the rotation of the drive pulley 17 induces a rearward movement 
of the belt holding bracket 23. Thus, the door 3 is moved rearward. 
It is to be noted that the time lag taken when the door 3 is actually moved 
after starting of the drive pulley 17 is quite advantageous in operating 
the other door controllers. 
For example, even if the lock cancelling operation of the lock canceller 36 
is somewhat delayed, the delayed movement of the door 3 by the belt 22 can 
compensate such mis-timed operation of the lock canceller 36. 
This means that the motor 11 for the door drive device can be started at 
the same time as or somewhat prior to the operation of the lock canceller 
36. 
As is known to those skilled in the art, simultaneous energization of two 
devices (viz., the motor 11 and lock cancellor 36) is easily controlled. 
Furthermore, if, after starting of the motor 11, the lock canceller 36 is 
actuated during the time when the slack of the belt 22 is being decreased, 
the restoring force of the door seal and the biasing force applied to the 
latch plate of the door lock 35 can be effectively used as an initial 
force for shifting the door 3 laterally outward from the full-closed 
position. 
When the door 3 is then moved rearward slightly from the laterally outward 
shifted position, the outside part of the belt 22 becomes detached from 
the front tensioner. It is to be noted that, under this condition, the 
stopper 32 stops an excessive pivoting of the arm 26 toward the belt 22. 
When then the door 3 is moved rearward to a slightly open position where 
the horizontal bracket 4 is positioned beside the junction zone 2c of the 
guide rail 2 as illustrated by a phantom line "X2" of FIG. 2, the 
projecting end 23a of the belt holding bracket 23 is positioned away from 
the tension roller 28 of the front tensioner, as shown. 
When then the door 3 comes to a position where the horizontal bracket 4 is 
positioned at the straight portion 2a of the guide rail 22 as illustrated 
by a phantom line "X3" of FIG. 2, the outside part of the belt 22 becomes 
in contact with the tension roller 28 of the front tensioner. Thereafter, 
the contact between the tension roller 28 of the front tensioner and the 
belt 22 is kept until the bracket 4 comes to the position "X4" of FIG. 2 
where the door 3 assumes its full-open position. 
When the door 3 thus comes to the full-open position, a limit switch (not 
shown) for sensing the full-open condition of the door 3 is operated to 
stop energization of the motor 11. While, when, during movement of the 
door 3 toward the full-open position, the door open control switch is 
turned OFF, energization of the motor 11 is stopped and thus the door 3 is 
forced to stop at a half-open position. 
When the door 3 stops at the full-open position or the half-open position, 
the arm 26 of each tensioner is forced to pivot in a clockwise direction 
in FIG. 2 by the force of the spring 31 thereby to apply a suitable 
tension to the belt 22. Thus, slack of the belt 22 is taken up or 
eliminated. During this, the drive pulley 17, the speed reduction gear 16 
and the output shaft 11a of the motor 11 may be somewhat driven by the 
tensioning force produced by the front and rear tensioners. 
When, with the door 3 assuming the full-open position or the half-open 
position, a door close control switch (not shown) positioned beside the 
above-mentioned door open control switch is manipulated to take ON 
position, the motor 11 is energized to turn in a reversed direction and 
thus the drive pulley 17 is rotated in a clockwise direction in FIG. 2. 
At a first stage, the rotation of the drive pulley 17 is used for 
eliminating the slack of the belt 22. During this slack elimination, the 
two tensioners are gradually pivoted toward their small-angled positions 
as illustrated by the phantom lines. 
When, due to elimination of the slack, the belt 22 becomes highly 
tensioned, the clockwise rotation of the drive pulley 17 induces a forward 
movement of the belt holding bracket 23. Thus, the door 3 is moved 
forward. 
When the door 3 comes to the power feeding position just before the 
half-latch position, the door-mounted connector part 39 is brought into 
engagement with the body-mounted connector part 38, and thus power feeding 
from the battery in the vehicle body to the door closure 37 in the door 3 
becomes available. When then the door 3 comes to the half-latch position 
wherein the latch plate of the door lock 35 is hafly latched with the 
striker of the vehicle body, the door closure 37 becomes energized. Thus, 
the latch plate of the door lock 35 is forced to pivot into its 
full-latched position forcing the door 3 to move to the full-closed 
latched position. 
It is to be noted that the movement of the door 3 from the half-latch 
position to the full-closed latched position is achieved by both the motor 
11 of the door drive device and the door closure 37. Thus, this movement 
is assuredly carried out. 
It is further to be noted that even when the speed at which the door is 
shifted from the half-latch position to the full-closed latched position 
by the door closure 37 is greater than the speed at which the door is 
shifted by the motor 11 of the door drive device, such mismatched 
operation can be compensated by having the belt 22 slackened between the 
drive pulley 17 and the belt holding bracket 23. 
When, with the door 3 assuming the full-open position or the half-open 
position, a manual labor is applied to the door 3 for the purpose of 
moving the door in the closing direction, only the door 3 and a part of 
the belt 22 are moved at a first stage. 
That is, at the first stage, the closing movement of the door 3 is used for 
eliminating the slack of the belt 22 tensioned by the rear tensioner. More 
specifically, as the first stage, the closing movement of the door 3 does 
not induce a movement of the entire of the belt 22 until the slack of the 
belt 22 is eliminated. 
When the slack of the belt 22 is eliminated and thus belt 22 becomes highly 
tensioned by the continued closing movement of the door 3, the drive 
pulley 17, the speed reduction gear 16 and the output shaft 11a of the 
motor 11 are driven by the movement of the door 3. 
Accordingly, an initial movement of the door 3 by manual labor in the door 
closing direction is easily carried out with a light force. That is, just 
at the time when the closing movement of the door 3 comes to have a 
sufficient inertial force, the drive pulley 17, the speed reduction gear 
16 and the output shaft 11a of the motor 11 are driven by the movement of 
the door 3. 
It is to be noted that a load applied to the door 3 when these three 
devices 17, 16 and 11 are driven produces a suitable check against the 
closing movement of the door 3 and thus the manual closing movement of the 
door 3 is carried out with a comfortable operation feeling. 
When, with the door assuming the full-closed latched position, it is needed 
to open the door 3 with a manual labor, a door handle (not shown) of the 
door 3 is manipulated to cancel the locked condition of the door lock 35. 
Upon this cancellation, the door 3 is somewhat shifted laterally outward 
due to the restoring force of the door seal. Thus, if this outward 
shifting of the door 3 is timely used, a subsequent opening movement of 
the door 3 is easily carried out with a light force. This easy movement of 
the door 3 in the opening direction is achieved irrespective of whether 
the slack of the belt 22 has been present or not before the movement of 
the door 3. 
If desired, the following modifications may be employed in the invention. 
(1) In place of the above-mentioned toothed belt 22, wire, chain and the 
like can be used. 
(2) One or more than two tensioners can be used for tensioning the belt 22. 
(3) In addition to the tensioners of the above-mentioned type, various 
types of tensioners are usable. One of them may be a type in which a 
spring biased tension roller is slidably held on a fixed holder which 
extends perpendicular to the path of the belt 22. 
In the following, advantages of the present invention will be described. 
(a) In the invention, there is no need of using an expensive 
electromagnetic clutch in the door drive device. That is, the output shaft 
11a of the motor 11 and the belt 22 are constantly connected. Thus, the 
door drive device of the present invention can have a simple, compact, 
light-weight and low-costed construction. 
(b) Because the belt 22 is put around the drive and driven pulleys 17 and 
20 with a suitable slack, the initial opening or closing movement of the 
door 3 by manual labor is easily carried out with a light force as has 
been described hereinabove. That is, due to the provision of the slack, 
the driving of the drive pulley 17, the speed reduction gear 16 and the 
output shaft 11a of the motor 11 by the manual movement of the door 3 is 
not effected until the movement of the door 3 has a sufficient inertial 
force. 
(c) In case wherein the door drive device of the invention is used in 
combination with the door closure and the door lock canceller in the 
above-mentioned manner, mis-timed operations of these devices can be 
compensated due to the provision of the slack of the belt 22. Thus, these 
devices are prevented from being applied with the excessive load.