Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
1999-12-17
2001-03-06
Wright, Dirk (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
Reexamination Certificate
active
06196077
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to an automatic shift control device for an electronic pneumatic shift system and a method for controlling the same. More particularly, the present invention relates to an automatic shift control device for an electronic pneumatic shift system and a method for controlling the same in which a linear variable distance transducer (LVDT) is used to reduce shift shock.
(b) Description of the Related Art
In trucks, buses and other such vehicles in which an engine is provided at a rear of the vehicle, since a transmission is positioned at a substantial distance from the driver, it is necessary that there is provided a shift device which precisely, smoothly and easily conveys the operation of a clutch and a gearshift lever by the driver to the transmission. A pneumatic shift system is often used instead of the conventional hydraulic or mechanical shift system. In the pneumatic shift system, air pressure is electronically controlled to ultimately change shift modes of the transmission.
FIG. 1
shows a schematic diagram of a general electronic pneumatic shift system to which the present invention is applied.
In the general electronic pneumatic shift system, a lever position sensor
6
detects an operation of a gearshift lever
4
L by the driver. The lever position sensor
6
outputs electrical signals corresponding to a changing position of the shift lever
4
L to an electronic control unit (ECU)
8
, and the ECU
8
outputs signals to control opened and closed states of a magnetic valve assembly
10
according to the signals received from the lever position sensor
6
. Accordingly, air is supplied to or exhausted from a shift control device
12
to control a transmission
14
into various forward and reverse shift modes.
The magnetic valve assembly
10
is connected to an air tank
15
and receives the supply of air from the air tank
15
. Also, by the supply and exhaust of air from and to the air tank
15
via a reaction valve
18
, which is a 3-way magnetic valve connected to a reaction cylinder (not shown), a shift feeling is provided to the driver when the gearshift lever
4
L is manipulated to different shift modes.
The ECU
8
is connected to a shift mode display
20
, and the ECU
8
performs control such that the shift mode display
20
displays the present shift mode after receiving signals from the lever position sensor
6
. The ECU
8
is also connected to a warning lamp
24
which alerts the driver either of either shift failure caused by the incorrect supply of air to the magnetic valve assembly
10
, or of the mis-operation of the gearshift lever
4
L by the driver. The ECU
8
detects such problems through its connection with a shift mode sensor
22
.
The shift control device
12
includes a cylinder MVA
26
and a cylinder MVB
28
. Air is supplied to and exhausted from the cylinder MVA
26
and the cylinder MVB
28
by the operation of the magnetic valve assembly
10
which operates according to signals output from the ECU
8
. A shift rod
30
is slidably disposed in the shift control device
12
. The shift rod
30
is displaced in a rightward or leftward direction (in the drawing) according to the supply of air to the cylinder MVA
26
and the cylinder MVB
28
.
A striker
32
is fixedly disposed on the shift rod
30
. With this configuration, when the shift rod
30
is displaced in the leftward direction, the striker
32
is also moved such that it operates the transmission
14
to either a first, third or fifth speed of a drive D range; and when the shift rod
30
is displaced in the rightward direction, the striker is moved such that it operates the transmission
14
to either a second or fourth speed of the drive D range, or into reverse. That is, when the driver operates the gearshift lever
4
L to different shift modes, the ECU
8
controls the magnetic valve assembly
10
so that air is supplied to or exhausted from the cylinder MVA
26
and the cylinder MVB
28
of the shift control device
12
, thereby controlling the displacement of the shift rod
30
and the striker
32
.
Also, provided on one end of the shift rod
30
is a magnet
34
. Magnet sensors
36
are mounted in the shift control device
12
corresponding to a position of the magnet
34
. Accordingly, the magnet sensors
36
are able to detect the changing position of the magnet
34
as the shift rod
30
is displaced.
However, in the general pneumatic shift system as described above, since air pressure is used to shift the transmission
14
into different shift modes, in the case where air is abruptly supplied to the shift control device
12
, the shift rod
30
and striker
32
are moved at a substantial speed such that abrupt force is applied to a synchronizer, shift fork, etc. of the transmission
14
. This results in the wear of the transmission
14
, as well as a reduction in shift and ride quality caused by shift shock.
SUMMARY OF THE INVENTION
The present invention has been made in an effort to solve the above problems.
It is an object of the present invention to provide an automatic shift control device for an electronic pneumatic shift system and a method for controlling the same in which a linear variable distance transducer (LVDT) is used to reduce shift shock.
To achieve the above object, the present invention provides an automatic shift control device for an electronic pneumatic shift system and a method for controlling the same. The shift control device detects a position of a gearshift lever through a lever position sensor, the lever position sensor outputting signals corresponding to the position of the gearshift lever to an electronic control unit such that the ECU controls a magnetic valve assembly to supply and exhaust air to the shift control device to thereby control a transmission. The shift control device includes a magnet disposed on one end a shift rod of the shift control device; and a linear variable distance transducer provided on an end of the shift control device corresponding to a position of the magnet, the LVDT detecting a change in a magnetic field caused by a movement of the shift rod, and the LVDT outputting signals corresponding to the change in the magnetic field to the ECU.
The method includes the steps of detecting a position of the gearshift lever; determining if there is a shift command; establishing a target position for the shift rod of the shift control device if there is a shift command; controlling the magnetic valve assembly to supply air to the shift control device; detecting a position of the shift rod; determining if the shift rod has come within 90% of the target position; calculating a present position, movement speed and acceleration of the shift rod if the shift rod has come within 90% of the target position; supplying air continuously and suitably to the shift control device until a target shift mode has been obtained; and determining if the target shift mode has been reached.
According to a feature of the present invention, in the step of determining if there is a shift command, if there is no shift command, the position of the gearshift lever is continuously detected.
According to another feature of the present invention, in the step of determining if the shift rod has come within 90% of the target position, if the shift rod has not come within 90% of the target position, the LVDT determines the position of the shift rod.
According to yet another feature of the present invention, in the step of determining if the target shift mode has been reached, if the target shift mode has not been reached, the present position, movement speed and acceleration of the shift rod are calculated.
REFERENCES:
patent: 5038627 (1991-08-01), Schwaigner et al.
patent: 5969519 (1999-10-01), Steiling et al.
Hyundai Motor Co.
Wright Dirk
LandOfFree
Automatic shift control device for electronic pneumatic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automatic shift control device for electronic pneumatic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automatic shift control device for electronic pneumatic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2532705