Fiat 1998 Marea Weekend, Service Manual

Page: 464 / 846

Auxilliary units
Climate control
Marea-Marea Weekend
99 range
50.
SAIMDEN SD7V16 COMPRESSOR (engine 1910 JTD)
The compressor fitted on this version is the SANDEN SD7V16 variable capacity type.
The capacity of the compressor varies starting from the maximum value (161.3 cm^/rev) and is gradually
reduced (up to 10.4 cm^/rev) according to the system load variations. - changed outside temperature
and/or humidity conditions or sharp variations in the engine load.
This solution is defined as "unlimited variable capacity".
The compressor is the alternating piston type: the variation in capacity is achieved by tilting the connect-
ing rod holder plate with a consequent variation of the piston stroke: the movement of the plate is acti-
vated by an internal regulation valve according to the balance of pressure upstream and downstream of
the compressor. In particular, a low intake pressure involves the shuttering of the compressor (reduced ca-
pacity), whilst a high pressure involves operation at maximum power (maximum capacity).
Operation
The SD7V16 compressor is illustrated in the diagram below: it consists of seven pistons (2) and connect-
ing rods (3) secured to a connecting rod holder plate (4). The rotary motion of the plate (4), on the shaft
(5) produces the alternating movement of the pistons.
Chaning the inclination of the plate alters the capacity: the maximum angle (as illustrated) produces the
maximum capacity; virtually zero inclination (vertical position) for the minimum capacity, almost zero.
The plate (4) rotates around the pin (6) hinged on the shaft (5) arm (7).
The movement of the plate (4) in relation to the shaft (5) takes place by means of splining made from a
low resistance material.
The plate (4) slides below along a guide (9) via a runner (8) made from a low friction material.
The diaphragm valve (1) controls the flow rate adjustment according to the difference between Pa (intake
pressure) and Pi (pressure inside the compressor).
N.B. the solution adopted for this compressor is designed to keep the internal pressure Pi constant, with
advantages in terms of ease of adjustment and quiet, smooth operation.
1. Diaphgram valve
2. Pistons
3. Connecting rods
4. Connecting rod plate
5. Shaft
6. Pin
7. Arm
8. Slide
9. Guide
Pa inlet pressure
Pi pressure inside the compressor
Pm supply pressure
7 6 4 3 2
Print n° 506.763/17