GB2036404A - Gear Change Simulation - Google Patents

Abstract

A gear change simulator, for training drivers of heavy vehicles, has a gear lever (10) coupled to several longitudinally movable bars (30). A respective friction brake (40) of the caliper type provides a resistance to movement of each bar and hence of the gear lever. Locking devices (72, 74) normally inhibit movement of the bars, but are operable independently of the friction brakes under the control of signals from a computer, which signals indicate when a respective gear change is permitted, to permit movement of the associated bar. <IMAGE>

Description

SPECIFICATION Gear Change Simulation This invention relates to a gear change simulator. Such a simulator is used in the training of drivers for heavy vehicles.

Gear change simulators have in particular to provide the gear lever with a load, so that the trainee feels resistance similar to that which occurs when the vehicle's gears enmesh, to inhibit selection of an inappropriate gear which would be impossible to engage in a real vehicle, and to inhibit engagement of any gear if the correct operation sequence is not followed (e.g.

the clutch is not disengaged).

Conventional gear change simulators of which we are aware have used an electromagnetic brake to provide the necessary loading. This has the advantage that it is relatively easily controlled by the simulator computer to provide either the controlled resistance simulating the vehicle gears meshing or the much harder resistance or "baulk" required to stop engagement of a gear.

However we have found that such simulators have been unsatisfactory in that it is sometimes possible for a trainee to "beat the baulk" by using sufficient force quickly enough and thus to engage a prohibited gear. Furthermore the loading provided by the electromagnetic brake tends to be spongy and is not a very realistic simulation of the feel which the driver actually receives when the real vehicle's gears mesh.

In accordance with this invention we provide a gear change simulator, comprising a usercontrolled gear selector member, control means for providing signals indicative of permitted gear changes, a friction brake arranged to provide a resistance to movement of the gear selector member, and mechanical locking means operable independently of the brake and selectively controlled by the control means to positively inhibit movement of the gear selector member.

In this way the two functions of baulking and providing feel are separated and provided by two different systems. This enables more effective baulking to be obtained, and allows a more realistic type of loading to be simulated by the use of a friction brake, which is preferably of the caliper type.

Preferably the operation is such that the mechanical locking means is normally in the movement-inhibiting position and is released only when a movement is specifically permitted.

Preferably the mechanical locking means is hydraulically actuated.

The friction brake preferably operates on a linearly movable member coupled to the selector member. Alternatively a rotatable member can be used. In either event, the locking means can conveniently operate on the same linearly movable or rotatable member. The latter member can be profiled to provide a varying frictional load.

The invention will now be described in more detail by way of example, with reference to the drawings, in which: Figure 1 is a schematic perspective view illustrating the components of a gear change simulator embodying the invention; Figure 2 is a front view of a caliper friction brake used in the simulator; Figure 3 illustrates the baulking operation; and Figure 4 shows the control connections to the baulking cylinders.

It is first convenient to describe the practical conditions in which baulking of the gear change is required in one specific example, which will be of a tracked vehicle having five forward gears (1 to 5) and two reverse gears, low and high (LR and HR), there being no synchromesh. Baulking is required if any one of the following conditions apply: (1) Correct operation sequence not used (see below).

(2) Gear demanded when vehicle moving too fast (see below).

(3) Reverse gear demanded when vehicle moving forward.

(4) Clutch not disengaged (in fact implicit in (1) but also applied as a separate condition).

With regard to (2), maximum permitted speeds are set for each gear. One set of typical values is as follows: Gear Max. Speed, MPH 1 2.5 2 6.3 3 10.1 4 15 5 LR 1.26 in reverse HR With regard to condition (1), there are two basic operation sequences, one of which must be followed: (a) If the vehicle is stationary; or if the vehicle is moving, when changing up on soft ground.

Correct sequence: (i) Disengage clutch (and obtain neutral if not already there).

(ii) Apply and release either steering lever.

(iii) Move gear lever from neutral.

(iv) Engage clutch.

(b) If the vehicle is moving, when changing upon hard ground, or when changing down.

Correct sequence: (i) Disengage clutch and obtain neutral.

(ii) Re-engage clutch.

(iii) Change engine R.P.M.-for upchange allow to fall below 1000, for downchange increase to above 2000.

(iv) Move gear lever from neutral.

(v) Engage clutch.

These baulking conditions can be changed so as to be appropriate for any desired vehicle. The conditions are tested in computer to determine whether baulking is required in a manner which is generally known and not therefore further described here.

Reference is now made to the drawings, and particularly to Figure 1 which shows a gear selector lever 10 mounted on a selector control assembly 12 which can be of known construction.

Conveniently the components 10 and 12 are taken from the actual vehicle type to be simulated. The permitted gear positions are indicated on Figure 1 at 14. Movement of the gear lever is transferred to sliding rods 1 6 which have between them interlock devices 1 8 to prevent more than one of the sliding rods 1 6 from moving at any one time.

Each rod 1 6 is pivotably connected to a lever 20 which is pivoted on an axis 22. A rod 24 is also connected to the lever so that the movement of the rod 1 6 is transmitted to the rod 24, though in the reverse direction. It will be seen that there is no gear position opposite the high reverse (HR) position, and a fixed stop or baulk 26 is provided for the appropriate one of the levers 20 to prevent inadvertent movement into the non-existent gear position. A ball and spring unit 28 engages in a recess 29 machined into the end portion of rod 16 or in the top of each lever 20 to simulate the neutral detent in the gear box.

A bar 30 conveniently of square section is coupled to the rod 24 so as to be linearly translated in response to movement of the gear lever into or out of an appropriate gear. To the other end of the bar 30 further connecting members 32, 34 and 36 couple the bar to a linear transducer 38 which provides an electrical output signal indicative of the bar position.

The bar 30 is provided with a friction brake device 40 of the caliper type, that is it comprises two pivoted arms 42 which bear on opposed sides of the bar 30. As shown in Figure 2, the arms 42 are mounted by a common pivot 44. The ends 50 of the arms to the other side of the pivot from the bar are urged apart as indicated by arrows 46 by means of disc springs 48. This forces the upper ends 52 of the arms, as seen in Figure 2, towards each other as shown by arrows 54. Friction pads 56 are mounted on the ends 52 of the arms 42 bearing against the bar 30. In this way a constant frictional force is brought to bear on the bar, providing a resistance to movement which is transmitted to the gear selector lever 10 so as to give a feel to the trainee of the way in which the gears enmesh.By varying the thickness of the bar 30 in accordance with a defined profile, differential loading can be provided as the bar slides between the pads 56. The profile can be determined empirically to match the feel of the vehicle being simulated and can vary as between one gear selection and another, arid between neutral and any in-gear position.

We have found that the feel provided by a system of this type, using a friction brake, is very realistic.

From the above description of the baulking conditions, it will be seen that it is not in fact necessary to provide a system which will baulk at every possible position through which the gear lever moves, as has been done hitherto, but it is sufficient if the baulk is available so as to stop movement from any of the in-gear positions, or from the neutral position. For this purpose the underside of bar 30 is provided with four detents 60, 62, 64 and 66 provided by the respective ends of two lands 68 and 70, as seen in Figures 3 and 4. Adjacent the bar 30 are positioned two hydraulic cylinders 72 and 74 controlling respective plungers 76 and 78 which engage selectively with the detents.

Referring now to Figure 3, diagram A illustrates the neutral position of one of the bars 30, assumed to be the bar associated with the first and LR gears. Plunger 76 engages detent 60 to inhibit movement into first gear and plunger 78 engages detent 66 to inhibit movement into low reverse. A small movement is permitted at the gear lever 10 to simulate the gears out of mesh condition. If low reverse is to be engaged, theR plunger 78 is removed by cylinder 74, allowing the bar to be moved to the position shown in diagram B, whereupon the plunger 78 is engaged against detent 64 to inhibit movement out of gear. However if it is first forward which is to be engaged, the plunger 76 is removed by the cylinder 72, allowing the bar to be moved to the position shown in diagram c. The plunger is then re-engaged and locks against detent 62 to inhibit movement out of gear.If the trainee attempts to move to a gear without following the correct operation sequence, the appropriate plunger is not removed.

The plungers are all engaged unless the conditions are such as to permit a particular movement. This is preferable to a system in which the plungers are only engaged when an attempted move is to be baulked. If the conditions are such that it is permissible to move into one of two or more gears, then all the respective plungers will be removed untii the desired move is established.

Reference is now made to Figure 4 which illustrates the way in which one pair of the hydraulic cylinders 72 and 74 are controlled. A high pressure line 80 contains a flow control valve 82 and a pressure relief valve 84. The high pressure line 80 and a return line 86 are connected to a hydraulic supply system, not shown. The output line 88 of the pressure relief valve 84 then constitutes a working pressure line.

Plunger 72 is connected to the pressure and return lines 88 and 86 via a changeover valve 90.

The changeover 90 has two positions in one of which it applies high pressure fluid to the lower chamber 92 in the cylinder 72, as shown, and in the other of which it applies the high pressure to the Upper chamber 94 of the cylinder 72. In this way the plunger can be forced upwards and downwards respectively. A similar changeover valve 96 controls the cylinder 74.

The hydraulic cylinders for the other three bars 30 are controlled in similar manner, except that only one cylinder is required for the bar seen on the left in Figure 1. The system could be pneumatic rather than hydraulic, provided the mechanical advantage was sufficiently high.

Each changeover valve has an electromagnetically controlled spool, not shown, by means of which its position can be changed. It is also spring biased towards the position in which the plunger is engaged. The spools are controlled by the simulator computer 98, shown in Figure 4, which receives signals from all the transducers 38 indicating the gear selector position, and also receives, or contains, signals indicative of clutch condition, assumed engine RPM, assumed vehicle speed, and steering lever condition, to enable the computer to test whether the baulking conditions apply. The manner in which this is done is analogous to known systems and in view of the foregoing description does not require further elucidation here. When the computer determines that it is permissible to move the gear lever to any one or more particular positions, it instructs the hydraulic cylinders to withdraw the relevant plunger or plungers.

In an alternative arrangement the changeover valves 90 and 96 can be servo rather than solenoid controlled. This can speed up the response of the system.

Claims (11)

Claims

1. A gear change simulator, comprising: a user-controlled gear selector member, control means for providing signals indicative of permitted gear changes, a friction brake arranged to provide a resistance to movement of the gear selector member, and mechanical locking means operable independently of the brake and selectively controlled by the control means to positively inhibit movement of the gear selector member.

2. A simulator according to claim 1, wherein the friction brake is of the caliper type.

3. A simulator according to claim 1 or 2, wherein the mechanical locking means is arranged normally to be in the movementinhibiting position and to be released when the control means provides a signal indicative of the gear change being permitted.

4. A simulator according to claim 1, 2 or 3, wherein the locking means is hydraulically or pneumaticaily actuated.

5. A simulator according to any preceding claim, wherein the friction brake acts on a member upon which the locking means operates.

6. A simulator according to any preceding claim, wherein the friction brake acts on a member which is profiled to provide a varying frictional resistance.

7. A simulator according to any preceding claim, wherein the friction brake acts on a linearly movable member.

8. A simulator according to any preceding claim, wherein the selector member has a neutral position in which it is retained by a detent device.

9. A simulator according to any preceding claim, wherein the selector member controls a plurality of individual members on which respective friction brakes operate.

10. A simulator according to claim 9, including interlock means for inhibiting simultaneous operation of more than one of said individual members.

11. A gear change simulator substantially as herein described with reference to the drawings.